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CHAPTER 9. AIRCRAFT SYSTEMS AND COMPONENTS

SECTION 1. INSPECTION AND MAINTENANCE OF LANDING GEAR

9-1. GENERAL.

a. The landing gear on aircraft may befixed or retractable. A fixed gear may bewheels, floats, or skis; and for amphibians acombination of floats and wheels.

b. Retractable gear on aircraft is usuallyoperated with hydraulic or electric power, al-though some models of light general aviationaircraft have manual retract systems operatedby a lever in the cockpit.

(1) In addition to the normal operatingsystem, emergency systems are usually pro-vided to ensure that the landing gear can belowered in case of main-system failure.

(2) Emergency systems consist ofbackup hydraulic systems, or stored nitrogengas bottles that can be directed into actuatingcylinders, mechanical systems that can be op-erated manually, or free-fall gravity systems.

9-2. GENERAL INSPECTION. A thor-ough inspection of the landing gear involvesthe entire structure of the gear, including at-tachments, struts, wheels, brakes, actuatingmechanisms for retractable gears, gear hydrau-lic system and valves, gear doors, and all asso-ciated parts. The manufacturer’s inspectionprocedures should be followed where applica-ble.

9-3. CLEANING AND LUBRICATING.It is recommended that only easily removableneutral solutions be used when cleaning land-ing gear components. Any advantage, such asspeed or effectiveness, gained by using clean-ers containing corrosive materials, can bequickly counteracted if these materials becometrapped in close-fitting surfaces and crevices.

Wear points, such as landing gear up-and-down latches, jack-screws, door hinges, pul-leys, cables, bellcranks, and all pressure-typegrease fittings, should be lubricated after everycleaning operation.

To prevent possible failure of a component dueto incompatibility or breakdown of the grease,the following should be observed:

1. Use only greases approved for use bythe product manufacturer.

2. Never mix different kinds of greasewithout approval from the productmanufacturer.

3. Follow the manufacturer’s instructionsor FAA approved process for cleaning,purging, and lubricating of the compo-nent.

To obtain proper lubrication of the main sup-port bushings, it may be necessary to jack theaircraft.

NOTE: Any time the aircraft is onjacks, check the landing gear mainsupport bushings for wear. Consultthe aircraft manufacturer’s overhaulmanual for specific wear tolerances.

During winter operation, excess grease maycongeal and cause increased loads on the gearretraction system, electric motors, and hydrau-lic pumps. This condition can lead to compo-nent malfunctions; therefore, it is recom-mended that cleanliness be stressed during andafter lubrication.

9-4. FIXED-GEAR INSPECTION. Fixedlanding gear should be examined regularly forwear, deterioration, corrosion, alignment, andother factors that may cause failure or unsatis-factory operation. During a 100-hour or an-

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nual inspection of the fixed gear, the aircraftshould be jacked up to relieve the aircraftweight. The gear struts and wheels should bechecked for abnormal play and corrected.

a. Old aircraft landing gear that em-ploys a rubber shock (bungee) cord for shockabsorption must be inspected for age, frayingof the braided sheath, narrowing (necking) ofthe cord, and wear at points of contact with thestructure and stretch. If the age of the shockcord is near 5 years or more, it is advisable toreplace it with a new cord. A cord that showsother defects should be replaced, regardless ofage.

b. The cord is color-coded to indicatewhen it was manufactured and to determinethe life of the shock cord. According toMIL-C-5651A, the color code for the year ofmanufacture is repeated in cycles of 5 years.Table 9-1 shows the color of the code threadfor each year and quarter year.

TABLE 9-1. Bungee cord color codes.

YEARS ENDINGWITH

COLOR QUARTER COLOR

0 or 5 Black 1st Red1 or 6 Green 2nd Blue2 or 7 Red 3rd Green3 or 8 Blue 4th Yellow4 or 9 Yellow 1st Red

c. The color coding is composed ofthreads interwoven in the cotton sheath thatholds the strands of rubber cord together. Twospiral threads are used for the year coding andone thread is used for the quarter of the yearsheath, e.g. yellow and blue would indicatethat the cord was manufactured in 1994 duringApril, May, or June.

d. Shock struts of the spring-oleo typeshould be examined for leakage, smoothnessof operation, looseness between the movingparts, and play at the attaching points. Theextension of the struts should be checked tomake sure that the springs are not worn or bro-

ken. The piston section of the strut should befree of nicks, cuts, and rust.

e. Air-oil struts should undergo an in-spection similar to that recommended forspring-oleo struts. In addition, the extensionof the strut should be checked to see that itconforms to the distance specified by themanufacturer. If an air-oil strut “bottoms”—that is, it is collapsed—the gas charge andhydraulic fluid has been lost from the airchamber. This is probably due to a loose ordefective air valve or to defective O-ring seals.

CAUTION: Before an air-oil strut isremoved or disassembled, the airvalve should be opened to make surethat all air pressure is removed. Se-vere injury and/or damage can occuras the result of disassembling a strutwhen even a small amount of air pres-sure is still in the air chamber.

f. The method for checking the fluidlevel of an air-oil strut is given in the manu-facturer’s maintenance manual. An alternatemeans of servicing an oil strut is to jack up theaircraft, remove the strut’s valve cap, releasethe air charge in the strut by depressing thevalve core, remove the strut’s valve core, at-tach a clean two-foot rubber or plastic hose tothe threaded portion that houses the valve core,and secure with a hose clamp. Put the otherend of the hose into a clean two quart con-tainer filled with the correct hydraulic fluid forthe strut. Cover the container with a clean ragto prevent spillage. Now, slowly raise thegear/strut assembly either manually or withanother jack under the strut. This will drivethe remaining air out of the strut into the con-tainer of hydraulic fluid. Once the gear is fullyretracted, slowly lower the gear. The hydraulicfluid in the can will be sucked into the strut.Repeat this procedure until you cannot hearany more air bubbles in the container when thewheel strut is fully retracted. With the strut

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fully retracted, remove the hose, insert thevalve core, lower the gear, and service the strutwith nitrogen to get the proper strut extension.

g. The entire structure of the landinggear should be closely examined for cracks,nicks, cuts, corrosion damage, or any othercondition that can cause stress concentrationsand eventual failure. The exposed lower endof the air-oleo piston is especially susceptibleto damage and corrosion, which can lead toseal damage, because the strut is compressedand the piston moves past the strut lower seal,causing the seal to leak fluid and air. Smallnicks or cuts can be filed and burnished to asmooth contour, eliminating the point of stressconcentration. If a crack is found in a landing-gear member, the part must be replaced.

h. All bolts and fittings should bechecked for security and condition. Bolts inthe torque links and shimmy damper tend towear and become loose due to the operationalloads placed on them. The nose-wheelshimmy damper should be checked for properoperation and any evidence of leaking. All re-quired servicing should be performed in accor-dance with the aircraft service manual.

9-5. INSPECTION OF RETRACTABLELANDING GEAR. Inspection of the retract-able landing gear should include all applicableitems mentioned in the inspection for the fixedgear. In addition, the actuating mechanismsmust be inspected for wear looseness in anyjoint, trunnion, or bearing; leakage of fluidfrom any hydraulic line or unit; and, smooth-ness of operation. The operational check isperformed by jacking the aircraft according tothe manufacturer’s instructions and then oper-ating the gear retracting and extending system.

a. During the operational test, thesmoothness of operation, effectiveness of up-and-down locks, operation of the warninghorn, operation of indicating systems, clear-ance of tires in wheel wells, and operation of

landing-gear doors should be checked. Im-proper adjustment of sequence valves maycause doors to rub against gear structures orwheels. The manufacturer’s checklist shouldbe followed to ensure that critical items arechecked. While the aircraft is still on jacks,the gear can be tested for looseness of mount-ing points, play in torque links, condition ofthe inner strut cylinder, play in wheel bearings,and play in actuating linkages. Emergencyblow down gear bottles should be inspected fordamage and corrosion and weighed to see ifthe bottle is still retaining the charge.

b. Mechanics should be aware that re-tread tires can be dimensionally bigger than a“new” tire. While this does not pose a prob-lem on fixed landing gear aircraft, it may pres-ent a serious problem when installed on re-tractable landing gear aircraft. It is stronglyrecommended that if a retread tire is installedon a retractable landing gear aircraft, a retrac-tion test be performed. With the gear in theup-and-lock position, the mechanic shoulddetermine that if the tire expands due to highambient temperature, heat generated from taxiand take-off, repeated landings, or heavybraking, the tire will not expand to the pointthat it becomes wedged in the wheel well.

c. The proper operation of the anti-retraction system should be checked in accor-dance with the manufacturer’s instructions.Where safety switches are actuated by thetorque links, the actual time of switch closingor opening can be checked by removing all airfrom the strut and then collapsing the strut. Inevery case, the adjustment should be such thatthe gear control cannot be placed in the UP po-sition or that the system cannot operate untilthe shock strut is at the full extended position.

9-6. EMERGENCY SYSTEMS. Exerciseemergency landing gear systems periodicallyto ensure proper operation and to prevent in-activity, dirt, and corrosion from rendering thesystem inoperative when needed. Most emer-

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gency systems employ either mechanical, pres-sure-bottle, or free-fall extension capabilities.Check for the proper safeties on triggeringmechanisms, and for the presence of requiredplacards, and necessary accessories such ascranks, levers, handles, etc. Emergency blow-down bottles should be checked for corrosiondamage, and then weighed to see if the bottleis still retaining the charge.

9-7. LANDING GEAR COMPONENTS.The following items are susceptible to servicedifficulties and should be inspected.

a. Shock Absorbers. Inspect the entireshock-strut for evidence of leaks, cracks, andpossible bottoming of the piston, as this con-dition causes overloading of landing-gearcomponents and contributes to fatigue cracks.Check all bolts, bolt holes, pins, and bushingsfor condition, lubrication, and proper torquevalues. Grease fitting holes (pressure-type) areespecially vulnerable to cracks and cross-threading damage. Check all safety wire andother locking devices, especially at the mainpacking gland nuts.

(1) When assembling shock-struts, usethe correct type and number of new “O”-rings,Chevron seals, and backup rings. Use only thecorrect filler valve core assembly, and followthe manufacturer’s instructions when servicingwith fluid and air. Either too much or too littleair or oil will affect aircraft handling charac-teristics during taxi, takeoff, and landing, andcan cause structural overloads.

(2) Shock cords and rubber discs dete-riorate with age and exposure. When this typeof shock absorber is used, inspect for generalcondition; i.e., cleanliness, stretching, fraying,and broken strands. These components shouldbe kept free of petroleum products as they ac-celerate deterioration of the rubber.

b. Nose Gear Assembly. Inspection ofthe steering mechanism should include torque-

links (scissors), torque-tubes, control rods androd-end bearings, shimmy dampers, cables,and turning stops. In addition, check all noselanding gear components, including mudscrapers and slush deflectors, for damage.

(1) Towing of some aircraft with therudder locks installed, may cause damage tothe steering linkage and rudder control system.Exceeding the steering or towing stop limitsshould be followed by a close inspection of theentire nose steering assembly. A brokensteering stop will allow turning beyond the de-sign limit, transmitting excessive loads tostructures, and to the rudder control system. Itis recommended that the nose steering arc lim-its be painted on the steering collar or fuselage.

(2) Inspect shimmy dampers for leakagearound the piston shaft and at fluid line con-nections, and for abnormal wear or loosenessaround the pivot points. Also check for properrigging, “bottoming” of the piston in the cylin-der, and the condition of the external stops onthe steering collar.

c. Tail Wheels. Disassembly, cleaning,and re-rigging of tail wheels are periodicallynecessary. Inspect them for loose or brokenbolts, broken springs, lack of lubrication, andgeneral condition. Check steerable tail wheelsfor proper steering action, steering-horn wear,clearances, and for security and condition ofsteering springs and cables.

d. Gear Doors. Inspect gear doors fre-quently for cracks, deformation, proper rig-ging, and general condition. Gear door hingesare especially susceptible to progressivecracking, which can ultimately result in com-plete failure, allowing the door to move andcause possible jamming of the gear. This con-dition could also result in the loss of the doorduring flight. In addition, check for propersafetying of the hinge pins and for distorted,sheared, loose, or cracked hinge rivets. Inspectthe wheel wells for improper location or rout-

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ing of components and related tubing or wir-ing. This could interfere with the travel of thegear door actuating mechanisms.

e. Wheels. Inspect the wheels periodi-cally for cracks, corrosion, dents, distortion,and faulty bearings in accordance with themanufacturer’s service information. In split-type wheels, recondition bolt holes which havebecome elongated due to some play in thethrough-bolt, by the use of inserts or otherFAA-approved means. Pay particular attentionto the condition of the through-bolts and nuts.Carefully inspect the wheels used with tubelesstires for damage to the wheel flange and forproper sealing of the valve. The sealing ringused between the wheel halves should be freeof damage and deformation. When boltingwheel halves together, tighten the nuts to theproper torque value. Periodically accomplishan inspection to ensure the nuts are tight andthat there is no movement between the twohalves of the wheel. Maintain grease retainingfelts in the wheel assembly in a soft, absorbentcondition. If any have become hardened, washthem with a petroleum-base cleaning agent; ifthis fails to soften them, they should be re-placed.

(1) Corrosion of wheels. Remove allcorrosion from the wheel half, and inspect it toensure that the wheel halves are serviceable.Apply corrosion prevention treatments as ap-plicable. Prime with a zinc chromate primer orequivalent, and apply at least two finish coats.

(2) Dented or distorted wheels. Re-place wheels which wobble excessively due todeformation resulting from a severe side-loadimpact. In questionable cases, consult the lo-cal representative of the FAA concerning theairworthiness of the wheels. Minor dents donot affect the serviceability of a wheel.

(3) Wheel bearings. When inspectingwheel bearings for condition, replace damaged

or excessively worn parts. Maintain bearingsand races as matched sets. Pack bearings onlywith the grease type called for in the manu-facturer’s maintenance manual prior to theirinstallation. Avoid pre-loading the wheelbearing when installing it on the aircraft bytightening the axle nut just enough to preventwheel drag or side play.

f. Brakes. Disassemble and inspect thebrakes periodically and examine the parts forwear, cracks, warpage, corrosion, elongatedholes, etc. Discolored brake disks are an indi-cation of overheated brakes and should be re-placed. If any of these or other faults are indi-cated, repair, recondition, or replace the af-fected parts in accordance with the manufac-turer’s recommendations.

g. Hydraulic Brakes. For proper mainte-nance, periodically inspect the entire hydraulicsystem from the reservoir to the brakes.Maintain the fluid at the recommended levelwith proper brake fluid. When air is present inthe brake system, bleed in accordance with themanufacturer’s instructions. Replace flexiblehydraulic hoses which have deteriorated due tolong periods of service and replace hydraulicpiston seals when there is evidence of leakage.

h. Micro-Switches. Inspect micro-switches for security of attachment, cleanli-ness, general condition, and proper operation.Check the associated wiring for chafing,proper routing, and to determine that protec-tive covers are installed on wiring terminals, ifrequired. Check the condition of the rubberdust boots which protect the micro-switchplungers from dirt and corrosion.

9-8. FLOATS AND SKIS. Aircraft oper-ated from water may be provided with either asingle float or a double float, depending uponthe design and construction; however, if anaircraft is an amphibian, it has a hull for flota-tion and then may need only wingtip floats.

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Amphibious aircraft have floats or a hull foroperating on water and retractable wheels forland operation.

a. Skis are used for operating on snowand ice. The skis may be made of wood,metal, or composite materials. There are threebasic styles of skis. A conventional ski, shownin figure 9-1, replaces the wheel on the axle.The shock cord is used to hold the toe of theski up when landing. The safety cable andcheck cable prevent the ski from pivotingthrough too great an angle during flight.

b. The wheel ski is designed to mount onthe aircraft along with the tire. The ski has aportion cut out that allows the tire to extend

slightly below the ski, so that the aircraft canbe operated from conventional runways withthe wheels or from snow or ice surfaces usingthe ski. This arrangement has a small wheelmounted on the heel of the ski, so that it doesnot drag on conventional runways.

c. In retractable wheel-ski arrangements,the ski is mounted on a common axle with thewheel. In this arrangement, the ski can be ex-tended below the level of the wheel for landingon snow or ice. The ski can be retracted abovethe bottom of the wheel for operations fromconventional runways. A hydraulic system iscommonly used for the retraction-system op-eration.

FIGURE 9-1. A typical ski installation.

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9-9. INSPECTION AND REPAIR OFFLOATS AND SKIS. Inspection of floatsand skis involves examination for damage dueto corrosion, collision with other objects, hardlandings, and other conditions that may lead tofailure. Tubular structures for such gear maybe repaired as described in the section cover-ing welded repairs of tubular structures.

a. Floats. To maintain the float in an air-worthy condition, periodic and frequent in-spections should be made because of the ra-pidity of corrosion on metal parts, particularlywhen the aircraft is operated in salt water. Ex-amine metal floats and all metal parts onwooden or fiberglass floats for corrosion, andtake corrective action in accordance with theprocedures described in Chapter 6, Corrosion,Inspection & Protection. Chapter 4, MetalStructure, Welding, and Brazing, outlinesmethods for repairing damage to metal floatsof aluminum and aluminum alloy structures.

Note: Blind rivets should not be used onfloats or amphibian hulls below the waterline.

In the case of wooden floats, make repairs inaccordance with general procedures outlined inChapter 1, Wood Structure. Repair fiberglassfloats in accordance with the manufacturer’sinstructions.

(1) If small blisters are noticed on thepaint, either inside or outside the float, thepaint should be removed and the area exam-ined. If corrosion is found, the area should becleaned thoroughly, and a coat of corrosion-inhibiting material applied. If the corrosionpenetrates the metal to an appreciable depth,replace the metal. Special attention should begiven to brace wire fittings and water rudder-control systems.

(2) If the hull or floats have retractablelanding gear, a retraction check should be per-formed along with the other recommendations

mentioned for retractable landing-gear sys-tems. Sheet-metal floats should be repairedusing approved practices; however, the seamsbetween sections of sheet metal should be wa-terproofed with suitable fabric and sealingcompound. A float that has undergone hull re-pairs should be tested by filling it with waterand allowing it to stand for at least 24 hours tosee if any leaks develop.

b. Skis and Ski Installation. Skis shouldbe inspected for general condition of the skis,cables, bungees, and fuselage attachments. Ifretractable skis are used, checks in accordancewith the general practices for retractable gearshould be followed. Ski manufacturers usuallyfurnish acceptable repair procedures. It is ad-visable to examine ski installations frequentlyto keep them maintained in airworthy condi-tion. If shock cord is used to keep the ski run-ner in proper trim, periodically examine to en-sure that the cord has enough elasticity to keepthe runner in its required attitude and the cordis not becoming loose or badly frayed. Re-place old or weak shock cords. When othermeans of restraint are provided, examine forexcessive wear and binding, and replace or re-pair as required. Examine the points of cableattachment, both on the ski and the aircraftstructure, for bent lugs due to excessive loadsthat have been imposed while taxiing overrugged terrain or by trying to break loose fro-zen skis. If skis that permit attachment to thewheels and tires are used, maintain proper tirepressure as under-inflated tires may push offthe wheels if appreciable side loads are devel-oped in landing or taxiing.

c. Repair of Ski Runners. Repair limitsare found in the applicable manufacturer’smanual. Fractured wooden ski runners usuallyrequire replacement. If a split at the rear endof the runner does not exceed 10 percent of theski length, it may be repaired by attaching oneor more wooden crosspieces across the top of

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the runner using glue and bolts. Bent or tornmetal runners may be straightened if minorbending has taken place and minor tears maybe repaired in accordance with procedures rec-ommended in Chapter 4, Metal Structure,Welding, and Brazing.

d. Ski Pedestals.

(1) Tubular Pedestals. Damaged ped-estals made of steel tubing may be repaired byusing tube splices as shown in the chapter onwelding.

(2) Cast Pedestals. Consult a FederalAviation Administration (FAA) representativeon the repair of cast pedestals.

9-10. TYPES OF LANDING GEARPROBLEMS. During inspection and beforeremoving any accumulated dirt, closely ob-serve the area being inspected while the wing-tips are gently rocked up and down. Excessivemotion between normally close-fitting landinggear components may indicate wear, cracks, orimproper adjustment. If a crack exists, it willgenerally be indicated by dirt or metallic parti-cles which tend to outline the fault. Seepageof rust inhibiting oils, used to coat internal sur-faces of steel tubes, also assists in the earlydetection of cracks. In addition, a sooty, oilyresidue around bolts, rivets, and pins is a goodindication of looseness or wear.

a. Thoroughly clean and re-inspect thelanding gear to determine the extent of anydamage or wear. Some components may re-quire removal and complete disassembly fordetailed inspection. Others may require a spe-cific check using an inspection process such asdye penetrant, magnetic particle, radiographic,ultrasonic, or eddy current. The frequency,degree of thoroughness, and selection of in-spection methods are dependent upon the age,use, and general condition of the landing gear.

b. Inspect the aircraft or landing gearstructure surrounding any visible damage toensure that no secondary damage remains un-detected. Forces can be transmitted along theaffected member to remote areas where subse-quent normal loads can cause failure at a laterdate.

c. Prime locations for cracks on anylanding gear are bolts, bolt holes, pins, rivets,and welds. The following are typical locationswhere cracks may develop.

d. Most susceptible areas for bolts are atthe radius between the head and the shank, andin the location where the threads join theshank, as shown in figure 9-2.

e. Cracks primarily occur at the edge ofbolt holes on the surface and down inside thebore. (See figures 9-3 and 9-4.)

FIGURE 9-2. Typical bolt cracks.FIGURE 9-3. Typical cracks near bolt holes.

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FIGURE 9-4. Typical bolt hole cracks.

f. The usual types of failure in rivetedjoints or seams are deformation of the rivetheads and skin cracks originating at the rivets’holes.

g. Cracks and subsequent failures of rodends usually begin at the thread end near thebearing and adjacent to or under the jam nut.(See figure 9-5.)

FIGURE 9-5. Typical rod-end cracks.

h. Cracks develop primarily along theedge of the weld adjacent to the base metal andalong the centerline of the bead.

i. Elongated holes are especially preva-lent in taper-pin holes and bolt holes or at theriveted joints of torque tubes and push-pullrods. (See figure 9-6.)

FIGURE 9-6. Typical torque tube bolt hole elongation.

j. Deformation is common in rods andtubes and usually is noticeable as stretched,bulged, or bent sections. Because deforma-tions of this type are difficult to see, feel alongthe tube for evidence of this discrepancy. De-formation of sheet-metal web sections, atlanding-gear component attachment points,usually can be seen when the area is high-lighted with oblique lighting.

9-11. SPECIAL INSPECTIONS. When anaircraft experiences a hard or overweightlanding, the mechanic should perform a specialstructural inspection of the aircraft, includingthe landing gear. Landing gear support trussesshould be inspected for cracked welds, shearedbolts and rivets, and buckled structures.Wheels and tires should be inspected forcracks and cuts, and upper and lower wing sur-faces should be inspected for wrinkles, defor-mation, and loose or sheared rivets. If anydamage is found, a detailed inspection is rec-ommended.

9-12. RETRACTION TESTS. Periodicallyperform a complete operational check of thelanding gear retraction system. Inspect thenormal extension and retraction system, theemergency extension system, and the indicat-ing and emergency warning system. Deter-mine that the actuating cylinders, linkage, slidetubes, sprockets, chain or drive gears, geardoors, and the up-and-down locks are in goodcondition and properly adjusted and lubricated,and the wheels have adequate clearance in thewheel wells. In addition, an electrical conti-nuity check of micro-switches and associatedwiring is recommended. Only qualified per-sonnel should attempt adjustments to the gearposition and warning system micro-switches.Follow the manufacturer’s recommendations.

9-13. TIRE AND TUBE MAINTE-NANCE. A program of tire maintenance canminimize tire failures and increase tire servicelife.

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a. Correct balance is important since aheavy spot on an aircraft tire, tube, or wheelassembly is likely to cause that heavy spot tohit the ground first when landing. This resultsin excessive wear at one spot and an early fail-ure at that part of the tire. A severe case ofimbalance causes excessive vibration duringtake-off and landing, especially at high speed.

b. A protective cover should be placedover a tire while servicing units that might dripfluid on the tire.

9-14. TIRE INSPECTION AND REPAIR.Tires should be inspected frequently for cuts,worn spots, bulges on the side walls, foreignbodies in the treads, and tread condition. De-fective or worn tires may be repaired or re-treaded. The term, retread, refers to severalmeans of restoring a used tire, whether by ap-plying a new tread alone or tread and side wallmaterial in varying amounts. The followingguidelines should be used for tire inspection:

a. Tread Wear. Inspect the tires visuallyfor remaining tread. Tires should be removedwhen tread has worn to the base of any grooveat any spot, or to a minimum depth as specifiedby the tire or aircraft manufacturer. Tires wornto fabric in the tread area should be removedregardless of the amount of tread remaining.

b. Uneven Wear. If tread wear is exces-sive on one side, the tire can be dismountedand turned around, providing there is no ex-posed fabric. Gear misalignment causing thiscondition should be corrected.

WARNING: Do not probe cuts orembedded foreign objects while tire isinflated.

c. Tread Cuts. Inspect tread for cuts andother foreign object damage, and mark withcrayon or chalk. Remove tires that have thefollowing:

(1) Any cuts into the carcass ply.

(2) Cuts extending more than half of thewidth of a rib and deeper than 50 percent ofthe remaining groove depth.

(3) Weather checking, cracking, cuts,and snags extending down to the carcass ply inthe sidewall and bead areas.

(4) Bulges in any part of tire tread,sidewall, or bead areas that indicate a separa-tion or damaged tire.

(5) Cracking in a groove that exposesfabric or if cracking undercuts tread ribs.

d. Flat Spots. Generally speaking, tiresneed not be removed because of flat spots dueto skid or hydroplane burns unless fabric is ex-posed. If objectionable unbalance results, re-move the tire from service.

e. Beads. Inspect bead areas next towheel flanges for damage due to excessiveheat, especially if brake drag or severe brakinghas been reported during taxi, takeoff or land-ing.

f. Tire Clearance. Look for marks ontires, the gear, and in the wheel wells thatmight indicate rubbing due to inadequateclearance.

g. Surface Condition. The surface con-dition of a tire can be inspected with the tire onthe aircraft. The tread should be checked forabnormal wear. If the tread is worn in thecenter of the tire but not on the edges, this in-dicates that the tire is over-inflated and the op-erational air pressure should be reduced. Onthe other hand, a tire worn on the edges, butnot in the center, indicates under-inflation.These indications are shown in figure 9-7.

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9-15. INFLATION OF TIRES. There isserious danger involved with inflating and tireassembly. The tire should not be inflated be-yond the recommended pressure (when it isnot being installed in a safety cage). Over-inflation can cause damage to the aircraft, aswell as personal injury. Under-inflation willcause excessive tire wear and imbalance. Theairframe manufacturer’s load and pressurechart should be consulted before inflating tires.Sufficiently inflate the tires to seat the tirebeads; then deflate them to allow the tube toassume its position. Inflate to the recom-mended pressure with the tire in a horizontalposition.

Tire check of storage aircraft should be done inaccordance with the applicable aircraft storagemanual.

9-16. PERSONAL SAFETY. When serv-icing aircraft tires, personnel should stand ei-ther in the front or rear of the wheel and avoidapproaching from either side of the tire. Seeillustration below:

TIRE DANGERSafe

Approach Area

DangerDo not stand orapproach here

DangerDo not stand orapproach here

SafeApproach Area

Personnel should wear protective eye gear toreduce the risk of eye injury due to inflationand deflation of tires.

FIGURE 9-7. Examples of tread wear indicating over-inflation and under-inflation.

NOTE: The use of nitrogen to inflatetires is recommended. Do not useoxygen to inflate tires. Deflate tiresprior to removing them from the air-craft or when built-up tire assembliesare being shipped.

9-17. DISASSEMBLE THE WHEEL inaccordance with aircraft manufacturer’s in-structions.

Do not attempt to disassemble wheel until thetire has been completely deflated: otherwiseserious injury or damage to equipment can re-sult.

Do not attempt to remove valve core until tirehas been completely deflated. Valve cores willeject at high velocity if unscrewed before airpressure has been released.

Never attempt to remove wheel bolts or breaktire beads loose until tire has been completelydeflated: otherwise, explosive separation ofwheel components will result.

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Do not pry between wheel flanges and tirebeads as this can damage the wheel and tire.

Use caution when removing wheel bolts ornuts.

Remove tire from wheel using a wheel de-mounting fixture.

Valve stem, fusible plugs, wheel keys, heatshields, balance weights, and associated hard-ware should not be removed if demountableflange only is to be removed for tire change.

Fusible plugs and bearing cups should not beremoved unless replacement is necessary, ifpaint is to be stripped, or if a thorough inspec-tion of the wheel is to be made.

When removal and replacement of fusibleplugs is required, remove by pressing out witha blunt instrument such as a wooden rod. Ex-ercise caution to ensure wheel sealing surfacesare not damaged.

9-18. REASSEMBLING THE WHEEL.The correct assembly of the wheel affects thebalance of the tire. After the wheel halves andbolts/nuts have been inspected and foundserviceable, put a little talc on the tube and in-sert it in the tire. Align the heavy spot of thetube (usually marked with a yellow line) withthe light spot of the tire (usually marked with ared dot). If the tube does not have a balancemark, align the valve of the tube with the bal-ance mark on the line. Remove the valve coreand inflate the tube momentarily to “seat” thetube and let the air run out. Put one wheel halfin the tire and align the wheel half with thevalve hole up with the valve on the tube. In-sert the other wheel half in the tire and alignthe bolt holes. Insert the wheel bolts andtorque to the manufacturer’s recommendedvalue.

NOTE: It is highly recommended thatthe tire be placed in a cage so that ifthe wheel fails, the mechanic is pro-tected from injury.

Again inflate the tube with 5 or 10 psi and letthe air out to re-seat the tube. Install the valvecore, and fill the tire to the recommended pres-sure.

9-19. SLIPPAGE. To reduce the possibilityof tire and tube failure due to slippage, and toprovide a means of detecting tire slippage, tiresshould be marked and indexed with the wheelrim. Paint a mark one inch wide and twoinches long across the tire side wall and wheelrim. Use a permanent type paint in a con-trasting color, such as white, red, or orange.Pre-flight inspection must include a check ofslippage marks for alignment. If the slippagemarks are not in alignment, a detailed inspec-tion must be made, the reason determined, andif necessary, the condition corrected before thenext flight.

NOTE: Mechanics should be awarethat retread tires can be diametricallybigger than a “new” tire. While thisdoes not pose a problem on fixedlanding gear aircraft, it may pose aproblem on retractable gear aircraft.Due to a 5 to 8 percent expansion ofthe tire caused by the ambient tem-perature, if a retread tire is installedon a retractable gear aircraft, it isstrongly recommended that a retrac-tion test be performed. This is to en-sure the tire will not become wedgedin the wheel well during take-off andlanding operation.

9-20. WHEEL INSPECTION. Checkwheels for damage. Wheels that are cracked ordamaged must be taken out of service for re-pair or replacement in accordance with themanufacturer’s instruction manual.

9/27/01 AC 43.13-1B CHG 1

Par 9-9 Page 9-12a (and 9-12b)

9-21. WHEEL INSTALLATION. Variousprocedures are used for installing wheel as-semblies on an aircraft.

a. The axle should first be cleaned and in-spected for surface damage, damage to the axlethreads, and the general condition and securityof bolts holding the axle onto the landing-gearleg. The wheel bearings should be cleaned andpacked with approved grease. The wheelbearing and tire must be inspected and assem-bled. Many aircraft have specific torque re-quirements for the wheel-retaining nuts. Thesetorque requirements may have two valuesspecified. The retaining nut is first tightenedto the higher value to seat the bearing. It isthen backed off and tightened to the lowervalue specified. While tightening the wheelretaining nuts, the wheel should be rotated.

b. Great care should be exercised to seethat the wheel-retaining nuts are not over-tightened. In the absence of specific instruc-tions, the wheel-retaining nut is tightened untilbearing drag is felt. The nut is then backed offabout one serration (castellation) or one-sixthturn before bending up the tab on the tab-lockwasher or installing the cotter pin.

c. The grease cover or wheel cover, ifused, is then installed. During this installationany required brake, air-pressure sensors, andspeed-sensor components should be installedand connected, as appropriate, for the specificaircraft.

9-22. 9.24. [RESERVED.]

9/8/98 AC 43.13-1B

Par 9-25 Page 9-13

SECTION 2. HYDRAULIC SYSTEMS

9-25. GENERAL. Hydraulic systems inaircraft provide a means for the operation ofaircraft components. The operation of landinggear, flaps, flight control surfaces and brakes islargely accomplished with hydraulic powersystems. Hydraulic system complexity variesfrom small aircraft that require fluid only formanual operation of the wheel brakes to largetransport aircraft where the systems are largeand complex. To achieve the necessary redun-dancy and reliability, the system may consistof several subsystems. Each subsystem has apower generating device (pump) reservoir, ac-cumulator, heat exchanger, filtering system,etc. System operating pressure may vary froma couple hundred psi in small aircraft and ro-torcraft to several thousand psi in large trans-ports. Generally, the larger the aircraft, themore mechanical work is required to controlthe aircraft’s various functions. Consequently,the system operating pressure increases ac-cordingly. Primarily, hydraulic power is gen-erated by either engine driven or electric motordriven pumps. The majority of hydraulicpumps are pressure compensated to provide aconstant output pressure at a flow-rate de-manded by the system. Some constant dis-placement pumps with a relief valve are usedon the smaller aircraft.

9-26. PURPOSES OF HYDRAULICSYSTEMS. Hydraulic systems make possiblethe transmission of pressure and energy at thebest weight per horsepower ratio.

9-27. TYPES OF HYDRAULIC FLUID.There are three principal categories of hydrau-lic fluids; mineral base fluids, polyalphaolefinbase, and phosphate ester base fluids. Whenservicing a hydraulic system, the technicianmust be certain to use the correct category ofreplacement fluid. Hydraulic fluids are notnecessarily compatible. For example, con-tamination of the fire-resistant fluid

MIL-H-83282 with MIL-H-5606 may renderthe MIL-H-83282 non fire-resistant.

a. Mineral-Base Fluids. MIL-H-5606,mineral oil-based hydraulic fluid is the oldest,dating back to the 1940’s. It is used in manysystems, especially where the fire hazard iscomparatively low. MIL-H-6083 is simply arust-inhibited version of MIL-H-5606. Theyare completely interchangeable. Suppliersgenerally ship hydraulic components withMIL-H-6083.

b. Polyalphaolefin-Based Fluids.MIL-H-83282, is a fire-resistant hydrogenatedpolyalphaolefin-based fluid developed in the1960’s to overcome the flammability charac-teristics of MIL-H-5606. MIL-H-83282 is sig-nificantly more flame resistant thanMIL-H-5606, but a disadvantage is the highviscosity at low temperature. It is generallylimited to -40 �F. However, it can be used inthe same system and with the same seals, gas-kets, and hoses as MIL-H-5606.MIL-H-46170 is the rust-inhibited version ofMIL-H-83282. Small aircraft predominantlyuse MIL-H-5606 but some have switched toMIL-H-83282, if they can accommodate thehigh viscosity at low temperature.

c. Phosphate Ester-Based Fluid (Sky-drol/Hyjet). These fluids are used in mostcommercial transport category aircraft, and areextremely fire-resistant. However, they are notfireproof and under certain conditions, theywill burn. The earliest generation of thesefluids was developed after World War II as aresult of the growing number of aircraft hy-draulic brake fires which drew the collectiveconcern of the commercial aviation industry.

(1) Progressive development of thesefluids occurred as a result of performance re-quirements of newer aircraft designs. The

AC 43.13-1B CHG 1 9/27/01

Page 9-14 Par 9-27

airframe manufacturers dubbed these new gen-erations of hydraulic fluid as “types” based ontheir performance. Today, types IV and Vfluids are used. Two distinct classes of typeIV fluids exist based on their density: class Ifluids are low density and class II are standarddensity. The class I fluids provide weightsavings advantages versus class II. Monsantoand Exxon are the suppliers of the type IVphosphate ester-based aviation hydraulic flu-ids.

(2) In addition to the type IV fluids thatare currently in use, type V fluids are beingdeveloped in response to industry demands fora more thermally stable fluid at higher operat-ing temperatures. Type V fluids will be moreresistant to hydrolytic and oxidative degrada-tion at high temperature than the type IV flu-ids.

d. Materials of Construction. Hydraulicsystems require the use of special accessoriesthat are compatible with the hydraulic fluid.Appropriate seals, gaskets, and hoses must bespecifically designated for the type of fluid inuse. Care must be taken to ensure that thecomponents installed in the system are com-patible with the fluid. When gaskets, seals,and hoses are replaced, positive identificationshould be made to ensure that they are made ofthe appropriate material.

(1) Phosphate ester-based hydraulicfluids have good solvency properties and mayact as plasticizer for certain polymers. Careshould be taken in handling to keep the fluidfrom spilling on plastic materials and paintfinishes.

(2) If a small amount of the fluid isspilled during handling, it must be cleaned upimmediately with a dry cloth. When largerquantities are spilled, an absorbent sweepingcompound is recommended. A final cleaningwith an approved solvent or detergent shouldremove any traces of fluid.

9-28. HANDLING HYDRAULIC FLUID.In addition to any other instructions providedin the aircraft maintenance manual or by thefluid supplier, the following general precau-tions must be observed in the handling of hy-draulic fluids:

a. Ensure that each aircraft hydraulicsystem is properly identified to show the kindof fluid to be used in the system. Identificationat the filler cap or valve must clearly show thetype of fluid to be used or added.

b. Never allow different categories of hy-draulic fluids to become mixed. Chemical re-actions may occur, fire resistant fluids maylose their fire resistance, seals may be dam-aged, etc.

c. Never, under any circumstances, serv-ice an aircraft system with a fluid differentfrom that shown on the instruction plate.

d. Make certain that hydraulic fluids andfluid containers are protected from contamina-tion of any kind. Dirt particles may cause hy-draulic units to become inoperative, cause sealdamage, etc. If there is any question regardingthe cleanliness of the fluid, do not use it.Containers for hydraulic fluid must never beleft open to air longer than necessary.

e. Do not expose fluids to high tempera-ture or open flames. Mineral-based fluids arehighly flammable.

f. The hydrocarbon-based hydraulicfluids are, in general, safe to handle. To workwith these fluids, reasonable handling proce-dures must always be followed. Take precau-tion to avoid fluid getting in the eyes. If fluidcontacts the eye, wash immediately with water.

9/8/98 AC 43.13-1B

Par 9-28 Page 9-15

g. When handling Skydrol/Hyjet hy-draulic fluids, gloves that are impervious tothe fluid must be worn. If skin contact occurs,wash with soap and water.

h. When handling phosphate ester-based fluid use eye protection. If the eye isexposed to fluid, severe eye pain will occur.

i. When Skydrol/Hyjet mist or vaporexposure is possible, a respirator capable ofremoving organic vapors and mists must beworn.

j. Ingestion of any hydraulic fluidshould be avoided. Although small amountsdo not appear to be highly hazardous, any sig-nificant amount should be tested in accordancewith manufacturer’s direction, followed withhospital supervised stomach treatment.

9-29. HYDRAULIC SYSTEM MAINTE-NANCE PRACTICES. The maintenance ofhydraulic and pneumatic systems should beperformed in accordance with the aircraftmanufacturer’s instructions. The following isa summary of general practices followed whendealing with hydraulic and pneumatic systems.

a. Service. The servicing of hydraulic andpneumatic systems should be performed at theintervals specified by the manufacturer. Somecomponents, such as hydraulic reservoirs, haveservicing information adjacent to the compo-nent. When servicing a hydraulic reservoir,make certain to use the correct type of fluid.Hydraulic fluid type can be identified by colorand smell; however, it is good practice to takefluid from the original marked container andthen to check the fluid by color and smell forverification. Fluid containers should alwaysbe closed, except when fluid is being removed.

b. Contamination Control. Contamina-tion, both particulate and chemical, is detri-mental to the performance and life of compo-nents in the aircraft hydraulic system. Con-

tamination enters the system through normalwear of components, by ingestion through ex-ternal seals, during servicing, or maintenancewhen the system is opened to replace/repaircomponents, etc. To control the particulatecontamination in the system, filters are in-stalled in the pressure line, in the return line,and in the pump case drain line of each system.The filter rating is given in terms of “micron,”and is an indication of the particle size thatwill be filtered out. The replacement intervalof these filters is established by the manufac-turer and is included in the maintenance man-ual. However, in the absence of specific re-placement instructions, a recommended serv-ice life of the filter elements is:

Pressure filters 3000 hrs.Return Filters 1500 hrs.Case drain filters 600 hrs.

(1) When replacing filter elements, besure that there is no pressure on the filter bowl.Protective clothing and a face shield must beused to prevent fluid from contacting the eye.Replace the element with one that has theproper rating. After the filter element has beenreplaced, the system must be pressure tested toensure that the sealing element in the filter as-sembly is intact.

(2) In the event of a major componentfailure, such as a pump, consideration must begiven to replacing the system filter elements,as well as the failed component. System filtersmay also be equipped with differential pres-sure (∆P) indicators. These indicators are de-signed to “pop-up” when the pressure dropacross the element reaches a predeterminedvalue caused by contamination held by theelement. The indicators are designed to pre-vent false indications due to cold start, pumpripple, and shock loads. Consequently, a filterwhose indicator has been activated must be re-placed. In fact, some indicator designs are

AC 43.13-1B 9/8/98

Page 9-16 Par 9-29

such that the indicator cannot be reset, unlessthe filter bowl is removed and the element re-placed.

c. Flushing a Hydraulic System. Wheninspection of hydraulic filters or hydraulicfluid evaluation indicates that the fluid is con-taminated, flushing the system may be neces-sary. This must be done according to themanufacturer’s instructions; however, a typicalprocedure for flushing is as follows:

(1) Connect a ground hydraulic teststand to the inlet and outlet test ports of thesystem. Verify that the ground unit fluid isclean and contains the same fluid as the air-craft.

(2) Change the system filters.

(3) Pump clean, filtered fluid throughthe system, and operate all subsystems until noobvious signs of contamination are foundduring inspection of the filters. Dispose ofcontaminated fluid and filter. (Note: A visualinspection of hydraulic filters is not always ef-fective.)

(4) Disconnect the test stand and capthe ports.

(5) Ensure that the reservoir is filled tothe FULL line or proper service level.

d. Inspections. Hydraulic and pneumaticsystems are inspected for leakage, worn ordamaged tubing, worn or damaged hoses, wearof moving parts, security of mounting for allunits, safetying, and any other condition speci-fied by the maintenance manual. A completeinspection includes considering the age, curedate, stiffness of the hose, and an operationalcheck of all subsystems.

(1) Leakage from any stationary con-nection in a system is not permitted, and iffound, it should be repaired. A small amount

of fluid seepage may be permitted on actuatorpiston rods and rotating shafts. In a hydraulicsystem, a thin film of fluid in these areas indi-cates that the seals are being properly lubri-cated. When a limited amount of leakage isallowed at any point, it is usually specified inthe appropriate manual.

(2) Tubing should not be nicked, cut,dented, collapsed, or twisted beyond approvedlimits. The identification markings or lines ona flexible hose will show whether the hose hasbeen twisted. (See figure 9.9.)

(3) All connections and fittings associ-ated with moving units must be examined forplay evidencing wear. Such units should be inan unpressurized condition when they arechecked for wear.

(4) Accumulators must be checked forleakage, air or gas preload, and position. If theaccumulator is equipped with a pressuregauge, the preload can be read directly.

(5) An operational check of the systemcan be performed using the engine-drivenpump, an electrically-operated auxiliary pump(if such a pump is included in the system), or aground test unit. The entire system and eachsubsystem should be checked for smooth op-eration, unusual noises, and speed of operationfor each unit. The pressure section of the sys-tem should be checked with no subsystems tosee that pressure holds for the required timewithout the pump supplying the system. Sys-tem pressure should be observed during opera-tion of each subsystem to ensure that the en-gine-driven pump maintains the required pres-sure.

e. Troubleshooting. Hydraulic systemtroubleshooting varies according to the com-plexity of the system and the components inthe system. It is, therefore, important that the

9/8/98 AC 43.13-1B

Par 9-29 Page 9-17

technician refer to the troubleshooting infor-mation furnished by the manufacturer.

(1) Lack of pressure in a system can becaused by a sheared pump shaft, defective re-lief valve, the pressure regulator, an unloadingvalve stuck in the “kicked-out” position, lackof fluid in the system, the check valve installedbackward, or any condition that permits freeflow back to the reservoir or overboard. If asystem operates satisfactorily with a groundtest unit but not with the system pump, thepump should be examined.

(2) If a system fails to hold pressure inthe pressure section, the likely cause is thepressure regulator, an unloading valve, a leak-ing relief valve, or a leaking check valve.

(3) If the pump fails to keep pressure upduring operation of the subsystem, the pumpmay be worn or one of the pressure-controlunits may be leaking.

(4) High pressure in a system may becaused by a defective or improperly-adjustedpressure regulator, an unloading valve, or byan obstruction in a line or control unit.

(5) Unusual noise in a hydraulic system,such as banging and chattering, may be causedby air or contamination in the system. Suchnoises can also be caused by a faulty pressureregulator, another pressure-control unit, or alack of proper accumulator action.

(6) Maintenance of hydraulic systemcomponents involves a number of standardpractices together with specialized proceduresset forth by manufacturers such as the re-placement of valves, actuators, and otherunits, including tubing and hoses. Care shouldbe exercised to prevent system contaminationdamage to seals, packings, and other parts, andto apply proper torque in connecting fittings.When installing fittings, valves, etc. alwayslubricate the threads with hydraulic fluid.

(7) Overhaul of hydraulic and pneu-matic units is usually accomplished in ap-proved repair facilities; however, replacementof seals and packings may be done from timeto time by technicians in the field. When aunit is disassembled, all O-ring and Chevronseals should be removed and replaced withnew seals. The new seals must be of the samematerial as the original and must carry the cor-rect manufacturer’s part number. No sealshould be installed unless it is positively iden-tified as the correct part and the shelf life hasnot expired.

(8) When installing seals, care shouldbe exercised to ensure that the seal is notscratched, cut, or otherwise damaged. When itis necessary to install a seal over sharp edges,the edges must be covered with shim stock,plastic sheet, or electrical tape.

(9) The replacement of hydraulic unitsand tubing usually involves the spillage ofsome hydraulic fluid. Care should be taken toensure that the spillage of fluid is kept to aminimum by closing valves, if available, andby plugging lines immediately after they aredisconnected. All openings in hydraulic sys-tems should be capped or plugged to preventcontamination of the system.

(10) The importance of the propertorque applied to all nuts and fittings in a sys-tem cannot be over-emphasized. Too muchtorque will damage metal and seals, and toolittle torque will result in leaks and loose parts.The proper torque wrenches with the appropri-ate range should be used in assembling systemunits.

f. Disposal of Used Hydraulic Fluids. Inthe absence of organizational guidelines, the

AC 43.13-1B CHG 1 9/27/01

Page 9-18 Par 9-29

technician should be guided by local, state, andfederal regulations, with regard to means ofdisposal of used hydraulic fluid. Presently, themost universally accepted procedure for dis-posal of phosphate ester-based fluid is incin-eration.

9-30. HYDRAULIC LINES AND FIT-TINGS. Carefully inspect all lines and fittingsat regular intervals to ensure airworthiness.Investigate any evidence of fluid loss or leaks.Check metal lines for leaks, loose anchorage,scratches, kinks, or other damage. Inspect fit-tings and connections for leakage, looseness,cracks, burrs, or other damage. Replace or re-pair defective elements. Make sure the linesand hoses do not chafe against one another andare correctly secured and clamped.

a. Replacement of Metal Lines. Wheninspection shows a line to be damaged or de-fective, replace the entire line or, if the dam-aged section is localized, a repair section maybe inserted. In replacing lines, always usetubing of the same size and material as theoriginal line. Use the old tubing as a templatein bending the new line, unless it is too greatlydamaged, in which case a template can bemade from soft iron wire. Soft aluminumtubing (1100, 3003, or 5052) under ¼-inchoutside diameter may be bent by hand.. For allother tubing use an acceptable hand or powertube-bending tool. Bend tubing carefully toavoid excessive flattening, kinking, or wrin-kling. Minimum bend radii values are shownin table 9-2. A small amount of flattening inbends is acceptable, but do not exceed75 percent of the original outside diameter.Excessive flattening will cause fatigue failureof the tube. When installing the replacementtubing, line it up correctly with the mating partso that it is not forced into alignment by tight-ening of the coupling nuts.

b. Tube Connections. Many tube con-nections are made using flared tube ends with

standard connection fittings: AN-818(MS 20818) nut and AN-819 (MS 20819)sleeve. In forming flares, cut the tube endssquare, file smooth, remove all burrs and sharpedges, and thoroughly clean. The tubing isthen flared using the correct 37-degree aviationflare forming tool for the size of tubing andtype of fitting. A double flare is used on softaluminum tubing 3/8-inch outside diameterand under, and a single flare on all other tub-ing. In making the connections, use hydraulicfluid as a lubricant and then tighten. Over-tightening will damage the tube or fitting,which may cause a failure. Under-tighteningmay cause leakage which could result in asystem failure.

CAUTION: Mistaken use of45-degree automotive flare formingtools may result in improper tubingflare shape and angle; causing misfit,stress and strain, and probable systemfailure.

c. Repair of Metal Tube Lines. Minordents and scratches in tubing may be repaired.Scratches or nicks not deeper than 10 percentof the wall thickness in aluminum alloy tubing,that are not in the heel of a bend, may be re-paired by burnishing with hand tools. Replacelines with severe die marks, seams, or splits inthe tube. Any crack or deformity in a flare isunacceptable and cause for rejection. A dentless than 20 percent of the tube diameter is notobjectionable unless it is in the heel of a bend.A severely-damaged line should be replaced;however, it may be repaired by cutting out thedamaged section and inserting a tube sectionof the same size and material. Flare both endsof the undamaged and replacement tube sec-tions and make the connection by using stan-dard unions, sleeves, and tube nuts. If thedamaged portion is short enough, omit the in-sert tube and repair by using one union andtwo sets of connection fittings.

9/27/01 AC 43.13-1B CHG 1

Par 9-30 Page 9-19

TABLE 9-2. Tube data.

Wrench torque for tightening AN-818 Nut (pound inch) Minimum bend radiiDash Nos. Tubing OD Aluminum-alloy tubing Steel tubing Aluminum-alloy tubing measured to tubing

Ref. inchesMinimum Maximum Minimum Maximum

(Flare MS33583) for useon oxygen lines only

centerline. Dimensionin inches.

Minimum Maximum Alum.Alloy

Steel

-2-3-4-5-6-8

-10-12-16-20-24-28-32

1/83/161/45/163/81/25/83/41

1-1/41-1/21-3/4

2

20255070

110230330460500800800--

1800

30356590

130260360500700900900--

2000

7595

135170270450650900120015201900

--2660

851051502003005007001000140016802100

--2940

------

100200300--------------

------

125250400--------------

3/87/169/163/4

15/161-1/41-1/21-3/4

33-3/4

5--8

--21/327/8

1-1/81-5/161-3/4

2-3/162-5/83-1/24-3/85-1/4

--7

d. Replacement of Flexible Lines. Whenreplacement of a flexible line is necessary, usethe same type, size, part number, and length ofhose as the line to be replaced. Check TSOrequirements. If the replacement of a hosewith a swaged-end type fitting is necessary,obtain a new hose assembly of the correct sizeand composition. Certain synthetic oils re-quire a specially compounded synthetic rubberhose, which is compatible. Refer to the air-craft manufacturer’s service information forthe correct part number for the replacementhose. If the fittings on each end are of the cor-rect type or sleeve type, a replacement may befabricated as shown in figure 9-8. Before cut-ting new flexible wire braided hose to theproper size, tape the hose tightly with maskingtape and cut in the center of the masking tapeto prevent fraying. The use of a mandrel willprevent cutting the inside of the hose when in-serting the fittings. Typical aircraft hose speci-fications and their uses are shown in table 9-3.Install hose assemblies without twisting. (Seefigure 9-9.) A hose should not be stretchedtight between two fittings as this will result inoverstressing and eventual failure. The lengthof hose should be sufficient to provide about5 to 8 percent slack. Avoid tight bends in flexlines as they may result in

failure. Never exceed the minimum bend radiias indicated in figure 9-10.

(1) Teflon hose is used in many aircraftsystems because it has superior qualities forcertain applications. Teflon is compoundedfrom tetrafluoroethylene resin which is unaf-fected by fluids normally used in aircraft. Ithas an operating range of -65°F to 450 °F. Forthese reasons, Teflon is used in hydraulic andengine lubricating systems where temperaturesand pressures preclude the use of rubber hose.Although Teflon hose has excellent perform-ance qualities, it also has peculiar characteris-tics that require extra care in handling. It tendsto assume a permanent set when exposed tohigh pressure or temperature. Do not attemptto straighten a hose that has been in service.Any excessive bending or twisting may causekinking or weakening of the tubing wall. Re-place any hose that shows signs of leakage,abrasion, or kinking. Any hose suspected ofkinking may be checked with a steel ball ofproper size. Table 9-4 shows hose and ballsizes. The ball will not pass through if thehose is distorted beyond limits.

(2) If the hose fittings are of the reus-able type, a replacement hose may be

AC 43.13-1B CHG 1 9/27/01

Page 9-20 Par 9-30

fabricated as described in figure 9-8. Refer tofigure 9-10 for minimum bend radii. When ahose assembly is removed, the ends should betied as shown in figure 9-11, so that the pre-formed shape will be maintained. Refer tofigure 9-12 for minimum bend radii for teflonhose.

(3) All flexible hose installations shouldbe supported at least every 24 inches. Closersupports are preferred. They should be care-fully routed and securely clamped to avoidabrasion, kinking, or excessive flexing. Ex-cessive flexing may cause weakening of thehose or loosening at the fittings.

e. O-Ring Seals. An understanding of O-ring seal applications is necessary to determinewhen replacement should be made. The sim-plest application is where the O-ring merelyserves as a gasket when it is compressedwithin a recessed area by applying pressurewith a packing nut or screw cap. Leakage isnot normally acceptable in this type of instal-lation. In other installations, the O-ring sealsdepend primarily upon their resiliency to ac-complish their sealing action. When movingparts are involved, minor seepage may benormal and acceptable. A moist surface foundon moving parts of hydraulic units is an indi-cation the seal is being properly lubricated.In pneumatic systems, seal lubrication is pro-vided by the installation of a grease-impregnated felt wiper ring. When systemsare static, seepage past the seals is not nor-mally acceptable.

f. Storage of replacement seals.(1) Store O-ring seals where tempera-

ture does not exceed 120° F.

(2) Keep seals packaged to avoid expo-sure to ambient air and light, particularly sun-light.

g. During inspection, consider the fol-lowing to determine whether seal replacementis necessary.

(1) How much fluid is permitted to seeppast the seals? In some installations minorseepage is normal. Refer to the manufacturer’smaintenance information.

(2) What effect does the leak have onthe operation of the system? Know the sys-tem.

(3) Does the leak of fluid create a haz-ard or affect surrounding installations? Acheck of the system fluid and a knowledge ofprevious fluid replenishment is helpful.

(4) Will the system function safelywithout depleting the reservoirs until the nextinspection?

h. Do’s and Don’ts that apply to O-ringseals.

(a) Correct all leaks from static sealinstallations.

(b) Don’t retighten packing glandnuts; retightening will, in most cases, increaserather than decrease the leak.

(c) Never reuse O-ring seals becausethey tend to swell from exposure to fluids, andbecome set from being under pressure. Theymay have minor cuts or abrasions that are notreadily discernible by visual inspection.

(d) Avoid using tools that mightdamage the seal or the sealing surface.

(e) Do not depend upon color-coding.Coding may vary with manufacturer

(f) Be sure that part number is correct(g) Retain replacement seals in their

package until ready for use. This providesproper identification and protects the seal fromdamage and contamination.

(h) Assure that the sealing surfacesare clean and free of nicks or scratches beforeinstalling seal.

9/27/01 AC 43.13-1B CHG 1

Par 9-30 Page 9-20a (and 9-20b)

(i) Protect the seal from any sharpsurfaces that it may pass over during installa-tion. Use an installation bullet or cover thesharp surfaces with tape.

(j) Lubricate the seal so it will slideinto place smoothly.

(k) Be sure the seal has not twistedduring installation.

i. Hydraulic System Pressure Test.When a flexible hose has been repaired oroverhauled using existing hardware and newhose material, before the hose is installed on

the aircraft it is recommended that the hose istested to at least 1.5 system pressure. A newhose can be operationally checked after it is in-stalled in the aircraft using system pressure.

j. Hydraulic Components. Hydrauliccomponents such as pumps, actuating cylin-ders, selector valves, relief valves, etc., shouldbe repaired or adjusted following the airplaneand component manufacturer’s instructions.Inspect hydraulic filter elements at frequentintervals and replace as necessary.

9/8/98 AC 43.13-1B

Par 9-30 Page 9-21

FIGURE 9-8. Hose assembly instructions (can be used for low pressure hydraulic fluid, and oil lineapplications).

AC 43.13-1B 9/8/98

Page 9-22 Par 9-30

TABLE 9-3. Aircraft hose specifications.

SINGLE WIRE BRAID FABRIC COVEREDMIL.

PART NO.TUBESIZEO.D.

HOSESIZEI.D.

HOSESIZEO.D.

RECOMM.OPER.

PRESS.

MIN.BURSTPRESS.

MAX.PROOFPRESS.

MINBEND

RADIUSMIL-H-8794- 3-LMIL-H-8794- 4-LMIL-H-8794- 5-LMIL-H-8794- 6-LMIL-H-8794- 8-LMIL-H-8794-10-LMIL-H-8794-12-LMIL-H-8794-16-LMIL-H-8794-20-LMIL-H-8794-24-LMIL-H-8794-32-LMIL-H-8794-40-LMIL-H-8794-48-L

3/161/4

5/16381/25/83/41

1 1/41 1/2

22 1/2

3

1/83/161/4

5/1613/321/25/87/8

1 1/81 3/8

1 13/162 3/8

3

.45

.52

.58

.67

.77

.921.081.231.501.752.222.883.56

3,0003,0003,0002,0002,0001,7501,750800600500350200200

12,00012,00010,0009,0008,0007,0006,0003,2002,5002,0001,4001,000800

6,0006,0005,0004,5004,0003,5003,0001,6001,2501,000700300300

3.003.003.384.004.635.506.507.389.0011.0013.2524.0033.00

Construction: Seamless synthetic rubberinner tube reinforced with one fiber braid,one braid of high tensile steel wire and cov-ered with an oil resistant rubber impregnatedfiber braid.

Identification: Hose is identified by specifi-cation number, size number, quarter yearand year, hose manufacturer’s identification.

Uses: Hose is approved for use in aircrafthydraulic, pneumatic, coolant, fuel and oilsystems.

Operating Temperatures: Sizes-3 through 12: Minus 65 °F. to plus 250 °F.

Sizes - 16 through 48: Minus 40 °F. to plus 275 °F.

Note: Maximum temperatures and pressuresshould not be used simultaneously.

MULTIPLE WIRE BRAID RUBBER COVEREDMIL

PAR NO.

TUBESIZEO.D.

HOSESIZEI.D.

HOSESIZEO.D.

RECOMM.OPER.

PRESS.

MIN.BURSTPRESS.

MIN.PROOFPRESS.

MIN.BEND

RADIUSMIL-H-8788- 4-LMIL-H-8788- 5-LMIL-H-8788- 6-LMIL-H-8788- 8-LMIL-H-8788-10-LMIL-H-8788-12-LMIL-H-8788-16-L

1/45/163/81/25/83/41

7/329/3211/327/169/1611/167/8

0.630.700.770.861.031.221.50

3,0003,0003,0003,0003,0003,0003,000

16,00014,00014,00014,00012,00012,00010,000

8,0007,0007,0007,0006,0006,0005,000

3.003.385.005.756.507.759.63

Hose Construction: Seamless synthetic rubber innertube reinforced with one fabric braid, two or more steelwire braids, and covered with a synthetic rubber cover (forgas applications request perforated cover).

Identification: Hose is identified by specification number,size number, quarter year and year, hose manufacturer’sidentification.

Uses: High pressure hydraulic, pneu-matic, coolant, fuel and oil.

Operating Temperatures: Minus 65 °F. to plus 200 °F.

9/8/98 AC 43.13-1B

Par 9-30 Page 9-23

RIGHT WAY WRONG WAYDo not bend or twist the hose asillustrated.

Allow enough slack in the hose lineto provide for changes in lengthwhen pressure is applied. Thehose will change in length from+ 2% to – 4%.

Metal end fittings cannot be con-sidered as part of the flexible por-tion of the assembly.

The use of elbows and adapterswill ensure easier installation and inmany installations will remove thestrain from the hose line andgreatly increase service life.

At all times keep the minimumbend radii of the hose as large aspossible to avoid tube collapsing.

FIGURE 9-9. Proper hose installations.

AC 43.13-1B 9/8/98

Page 9-24 Par 9-30

FIGURE 9-10. Minimum bend radii.

9/27/01 AC 43.13-1B CHG 1

Par 9-30 Page 9-25

TABLE 9-4. Ball diameters for testing hose restrictionsor kinking.

HOSE SIZE-4-5-6-8-10-12-16-20

BALL SIZE5/649/6413/649/323/81/2

47/6461/64

FIGURE 9-11. Suggested handling of preformed hose.

AC 43.13-1B CHG 1 9/27/01

Page 9-26 Par 9-30

Figure 9-12. Minimum bend radii–Teflon hose.

9.31. 9.36 [RESERVED.]

9/8/98 AC 43.13-1B

Par 9-37 Page 9-27

SECTION 3. EMERGENCY EQUIPMENT

9-37. LIFE RAFTS. Inflatable life rafts aresubject to general deterioration due to aging.Experience has indicated that such equipmentmay be in need of replacement at the end of5 years due to porosity of the rubber-coatedmaterial. Wear of such equipment is acceler-ated when stowed on board aircraft because ofvibration which causes chafing of the rubber-ized fabric. This ultimately results in localizedleakage. Leakage is also likely to occur wherethe fabric is folded because sharp corners areformed. When these corners are in contactwith the carrying cases or with adjacent partsof the rubberized fabric, they tend to wearthrough due to vibration (Ref: TSO-C70a).

a. When accomplishing maintenance,repair, and inspection of unpacked rafts, per-sonnel should not step on any part of the raft orflotation tubes while wearing shoes. Raftsshould not be thrown or dropped, since dam-age to the raft or accessories may result. Par-ticular care should be exercised at all times toprevent snagging, cutting, and contact withgasoline, acids, oils, and grease. High stan-dards of performance for proper maintenance,inspection, and repair cannot be overempha-sized, since the lives of passengers could beinvolved.

b. Inspection and inflation tests, whenapplicable, will be accomplished during stor-age and after installation in an aircraft in ac-cordance with the manufacturer’s specifica-tions and/or FAA-approved procedures. Ac-cessory items will be installed during these in-spections. A raft knife will be attached by a24-inch nylon lanyard to the mooring eye lo-cated above the CO2 cylinder case to enablerapid cutting of the mooring line.

9-38. LIFE RAFT INSPECTIONS. In-spection of life rafts should be performed inaccordance with the manufacturer’s

specifications. General inspection proceduresto be performed on most life rafts are as fol-lows.

CAUTION: Areas where life rafts areinspected or tested must be smooth,free of splinters, sharp projections,and oil stains. Floors with abrasivecharacteristics, such as concrete orrough wood, will be covered with un-treated tarpaulins or heavy clean pa-per.

a. Inspect life rafts for cuts, tears, orother damage to the rubberized material. If theraft is found to be in good condition, removethe CO2 bottle(s) and inflate the raft with air toa pressure of 2 psi. The air should be intro-duced at the fitting normally connected to theCO2 bottle(s). After at least 1 hour, to allowfor the air within the raft to adjust itself to theambient temperature, check pressure and ad-just, if necessary, to 2 psi and allow the raft tostand for 24 hours. If, after 24 hours, the pres-sure is less than 1 psi, examine the raft forleakage by using soapy water. In order toeliminate pressure variations due to tempera-ture differences at the time the initial and finalreading are taken, test the raft in a room wherethe temperature is fairly constant. If the pres-sure drop is satisfactory, the raft should beconsidered as being in an airworthy conditionand returned to service after being fitted withcorrectly charged CO2 bottles as determined byweighing them. Rafts more than 5 years oldare likely to be unairworthy due to deteriora-tion. It is suggested that serviceable rafts bemarked to indicate the date of inspection andthat soapstone be used when folding them pre-paratory to insertion into the carrying case.Take care to see that all of the raft’s requiredequipment is on board and properly stowed. Ifthe raft lanyard, used to prevent the raft fromfloating away from the airplane, is in need of

AC 43.13-1B CHG 1 9/27/01

Page 9-28 Par 9-38

replacement, use a lanyard not less than 20 feetlong and having a breaking strength of about75 pounds.

b. It is recommended that the aforemen-tioned procedure be repeated every 18 monthsusing the CO2 bottle(s) for inflation. If a sin-gle bottle is used for inflating both compart-ments, it should be noted whether the inflationis proceeding equally to both compartments.Occasionally, the formation of “carbon-dioxidesnow” may occur in one passage of the distri-bution manifold and divert a larger volume ofgas to one compartment, which may burst ifthe mattress valve is not open to relieve thepressure. If the pressure is satisfactory, returnthe raft to service in accordance with the pro-cedure outlined.

c. Inspect the CO2 cylinder for evidenceof cross-threading or stripping.

d. Inspect the CO2 bottle inflation valvecable rigging as follows.

(1) Remove the screws that attach thecover plate to the valve and remove the coverplate.

(2) Inspect the firing line cable ballswage for engagement in the correct recess foreither “Upward Pull” or “Downward Pull.”The cable will be wrapped around the sheaveapproximately 270 degrees.

(3) Reposition the cable ball swage asrequired. (See figure 9-12.)

(4) Replace the cover plate. The greendot on the sheave should be visible through thewindow in the cover plate, indicating acharged cylinder.

e. Check the CO2 cylinder release cableand housing for condition and security.

f. Make sure the safety deflector is re-moved from the cylinder outlet before con-necting the cylinder to the raft. (Seefigure 9-12.)

g. Stencil the life raft’s inspection date onthe raft.

9-39. SURVIVAL KIT INSPECTION.

a. Survival Kit Contents. Each raft ac-commodating passengers or crew membersshould contain, as a minimum, the following:

Hand Pump (if required)Desalting Kit, First-Aid KitMirror/ReflectorEmergency RationsTarpaulinsFishing KitRaft KnifeCompassProtective Ointment (Sunburn)OarsEmergency Water ContainersRepair KitsSignal FlaresCarrying CaseLocator Beacon and BatteryLines and AnchorPolice WhistleFlashlightThermal Protective AidLight-sticksSolar Still KitSurvival ManualDuct TapePlastic Trash BagsAccessory Containers - Bailing Bucket - SpongeDye Marker

9/8/98 AC 43.13-1B

Par 9-39 Page 9-29

FIGURE 9-12. Inflation valve.

b. Exposure Suits. Quick-donning expo-sure suits should be provided in sufficientquantity to accommodate the passengers andcrew on extended over-water missions when-ever any of the following conditions exist.

(1) The water temperature is 59 �F orbelow, or

(2) The Outside Air Temperature (OAT)is 32 �F or below.

c. Physical Inspection. Make a physicalinspection of the life raft’s accessories and/orcontents, in accordance with manufacturer’sspecifications, to ascertain that all items re-quired are in a serviceable condition.

(1) Pumps and Hoses.

(a) Check the air pump for conditionand security.

(b) Check the air pump hose andhose fittings for ease of attachment to thepump and mattress valves.

(c) Operate the pump to ensure that itdelivers air.

(d) Close the outlet and check theseal of the piston.

(e) Blow into the outlet to determineif the pump check valve will seal.

(2) Desalting Kit.

(a) Check the desalting kit expirationdate, if applicable.

(b) Replace the severely dented orpunctured cans.

NOTE: Type MK-2 desalter kits havean indefinite shelf and service life anddo not have to be age-controlled.

(3) First-Aid Kit. Inspect each kit priorto flight to ensure that the seal is intact; thekits have not been tampered with or opened;and check the date when the kit contentsshould be inspected (120-day interval), andcontaining the following:

AC 43.13-1B 9/8/98

Page 9-30 Par 9-39

1 Case First-Aid Kit, empty;1 Bottle Benzalkonium Chloride Zinc; Tinted, 1:1000 2cc1 Package Sodium Chloride; (Sodium Bicarbonate Mix) 4.5 gm;1 Bandage each, Gauze, & Compress (2 inches x 6 yd);2 Dressings, First-Aid, 4 inches x 7 inches;1 Package Bandages; Absorbent & Adhesive, 3/4-inch x 3 inches;3 Bottles, Snap-On Cap, Plastic Tablet

and Capsule, Round, (issued empty; to be used as needed by user);

1 Tube Lipstick, Anti-Chap; and1 bottle Water Purification Tablets,

Iodine 8 mg (50).

(a) If the seal is found to be broken,or there is evidence of tampering, the kitshould be opened and inspected to ensure thatall components are included and undamaged.After such inspection, the kit should be re-sealed.

(b) To reseal the kit, use a wire andlead seal according to the manufacturer’sspecifications. Pass the wire through grom-mets or opposite flaps, bend the wire back andforce each end through the middle of the lacingcord on each side of the square knot. Pass theends of the wire through the holes in the leadseal, draw the wire taut, and compress the seal.

(4) Mirror/Reflector. Check the reflec-tor for defective reflection surface and the re-flector lanyard for defective conditions and se-curity of attachment.

(5) Emergency Rations. Check the foodration cans for obvious damage, severe dents,and an expiration date. Replace items whenseverely damaged, dented, or when the date isexpired. Ensure that the opening key is at-tached.

(6) Tarpaulins. Spread out and checkfor tears, mildew, corroded grommets, andgeneral condition.

(7) Fishing Kit. Check for damagedcontainer or for tampering. Replace if dam-aged or incomplete.

(8) Raft Knife. Check for corrosion andease of opening and security of the knife lan-yard to the raft.

(9) Compass. Check for proper opera-tion and condition.

(10) Protective Ointment (Sunburn).

(a) Check the sunburn ointmentcontainers for cracks or crushed condition.

(b) Install the ointment in a 6 inchmailing tube and tape the ends to preventcrushing. Stow it where it will be subjected tothe least amount of pressure in the kit.

(11) Oars.

(a) Check for serviceability.

(b) Wrap the oars separately in craftpaper and seal with tape.

(c) Stencil inspected in letters notless than 1/2-inch high on each package.

(12) Emergency Water Containers.Check for open seams, holes, etc. Replace de-fective containers.

(13) Repair Kit. Check for properwrapping and missing items. Four plugs arewrapped in a single container. This containerand the pliers are wrapped in waterproof paperand sealed with waterproof tape. The packageis stenciled repair plugs and pliers with lettersnot less than 1/2-inch high.

9/8/98 AC 43.13-1B

Par 9-39 Page 9-31

(14) Signal Flares. Check the flares forobvious damage and suspended lot numbers.Replace if lot number is over-age or obviousdamage exists.

(15) Carrying Case. Check for snags,abrasions, and defective snaps. Repair or re-place as necessary.

(16) Locator Beacon and Battery.

(a) Check for corrosion and obviousdamage per the manufacturer’s manual.

(b) Assemble as an operating unit.Perform an operational test, prepare the beaconfor water activation by pulling out the batteryswitch plug from the end of the transmittersection, and package as instructed on the con-tainer.

(17) Lines and Anchor. Check all linesand sea anchors for conditions and security.

(18) Police Whistle. Inspect and test.

(19) Flashlight. Test the flashlightswitch for operation; remove old batteries andinspect the case for corrosion and condition;and install new batteries and test momentarilyfor operation.

(20) Space Blankets. Check spaceblankets (if required) for rips, tears, and obvi-ous damage.

(21) Light-sticks. Inspect light-sticksfor condition and check expiration date.

(22) Solar Still Kit. Check the solarstill kit for condition.

(23) Survival Manual. Inspect the sur-vival manual for condition and completeness.

(24) Duct Tape. Check the duct tape fordeterioration.

(25) Plastic Trash Bags. Assure thatthree (each) plastic trash bags are serviceable.

(26) Accessory Containers.

(a) Check the containers for condi-tion and security.

(b) Repack the accessories, secure,and record the inspection data on data cards.Record the Inspection date.

(27) Dye Marker. Check for dents andoverall condition.

(28) Shark Chaser. Check for dents andoverall condition.

d. After Inspection. Replace accessoriesin the container, close, and tie securely withtying tapes. Draw a 25-pound breakingstrength cord tightly around the center and oneapproximately 5 inches from each end of thecontainer, tie with square knots, and seal witha lead seal.

e. Folding Life Rafts. Fold the life raftsper the manufacturer’s folding diagram usingsoapstone and secure the raft in its container.Check the container for obvious damage.

9-40. SPECIAL INSPECTIONS. Life raftsin storage or in service shall be unpacked andthoroughly inspected for mildew wheneverweather or other conditions warrant. The ex-tent of a special inspection will be determinedby the inspector or maintenance chief follow-ing a review of the circumstances or conditionsto which the life rafts have been subjected. Theinspector or maintenance chief may direct acomplete overall inspection and inflation test

AC 43.13-1B 9/8/98

Page 9-32 Par 9-40

of the life rafts, regardless of the last date ofinspection, if it is considered that another in-spection is warranted.

9-41. INSPECTION RECORD. The datethe inspection was completed will be stenciledon the flotation tube at the left of the cylinder.The size of lettering will not be less than1/4-inch or greater than 1/2-inch in height.Previous inspection dates will not be removedor obliterated, but will be arranged in columnarform with the latest date at the top. After theinspection is completed, fill out the raft’s in-spection record in accordance with part 43 sec-tion 43.9, and attach the parts tag to the survivalequipment. The date on the tag will reflect thesame date as stenciled on the flotation tube andwill be used to determine the next due date ofinspection and test.

9-42. RAFT REPAIRS.

a. Repairs. The service life for flotationequipment will be determined by conditionrather than age. Equipment passing tests andinspections may remain in service indefinitelysince the inflation tests and material inspec-tions will identify and condemn equipmenthaving more than minor installation defects.However, the service life for life rafts operat-ing under normal usage and environmentalconditions is anticipated by the manufacturersto be 8 to 10 years, and it is appropriate to baselife raft’s parts replacement programs upon thisestimate. It is not considered advisable or eco-nomical to perform major repairs on life rafts.

b. Life Rafts. Life rafts with any of thefollowing conditions should be condemnedrather than repaired:

(1) Life rafts over 3-1/2 years of ageand requiring major repair or more than twominor repairs.

(2) A rip or tear across an air retainingseam.

(3) Rafts on which oil, grease, or anyother foreign substance has caused a deteriora-tion of the rubberized fabric.

(4) Rafts on which a heavy mildewcondition has caused deterioration of the rub-berized fabric.

(5) Rafts on which porous flotationtubes allow diffusion of air. A porous area islocated by a soap test on the inflated raft.Higher diffusion is indicated by the excessiveloss of pressure after a soap test has failed tolocate a specific area of injury on the raft.

(6) Rafts requiring internal repair oropening of air retaining seams for repair.

(7) Rafts with an excessive number ofinjuries that would not, in the judgment ofcompetent inspectors, justify repair.

c. Patches. Holes or abrasions which are2 inches or less, in diameter (in air retainingchambers) will be repaired by the applicationof an outside patch. Holes exceeding 2 inchesin length or diameter, will require an insidepatch as well as an outside patch. Inside andoutside patches should be round or rectangularand manufactured of fabric (specificationMIL-C-6819). Cement should conform toClass 1 of specification MIL-C-5539. Patch asfollows:

(1) Outside patches.

(a) With a rubber solvent thoroughlyclean the area to be patched.

(b) From the material referenced,fabricate a patch as shown in figure 9-13.

9/8/98 AC 43.13-1B

Par 9-42 Page 9-33

(c) When two fabric surfaces are tobe bonded, apply two coats of extra light ce-ment, two coats of light cement, and threecoats of heavy cement to each surface. Rubber-coated tape and seam crossover patches withprotective backing do not require cement. Eachcoat of cement should be thoroughly dry to thetouch before the next coat is applied. Start thebonding of fabric surfaces while the last coatof cement is slightly tacky. To ensure properadhesion when bonding two cemented sur-faces, the areas to be bonded should remaintacky during application. This is accomplishedby brushing the cemented area with a clothmoistened with solvent.

NOTE: If difficulty in the drying ofheavy cement is encountered due toatmospheric conditions, six additionalcoats of light cement may be substi-tuted for the three coats of heavy ce-ment.

(d) After applying the patch, thor-oughly roll it with a hand roller, rolling fromthe center to the outer edge, to ensure that allair pockets are removed and a firm bond is se-cured.

(e) Thoroughly dust with talc. Allowto cure for 60 hours before performing leaktests and storing.

(2) Inside Patches.

(a) Cut a rectangular patch as shownin figure 9-13, allowing at least 1-1/2 inches toextend beyond the edge of the injury in all di-rections.

(b) Mark the center line on the sideof the patch that is to be attached to the raft.Mark cross lines on each end of the patch1-1/2 inches from the ends. When the patch isapplied to the injury on the inside, the longitu-dinal edges of the injury will coincide with the

center line, and cross lines on the ends of thepatch will coincide with the ends of the injury.

(c) To ensure that the inside surfaceof the raft is properly powdered in the area ofrepair, pass a small handful of talc through theopening in the raft and place it approximately12 inches from the injury. This should be ac-complished before the inside area is cemented,exercising care to prevent distribution of thetalc prior to completion of the repair.

FIGURE 9-13. Repair dimensions.

(d) Using cleaning solvent, cleansean area on the inside surface of the fabricslightly larger than the patch to be applied. En-sure that the repaired area is thoroughly dry,both inside and outside; apply two coats ofextra light cement, two coats of light cement,and three coats of heavy cement (or six addi-tional coats of light cement in lieu of the heavycement) to the cleansed area, allowing eachcoat to dry thoroughly before applying succes-sive coats.

NOTE: Since it is impossible for therepairman to visually observe the ce-menting that is being accomplished onthe inside of the raft, exercise care toensure that each coat of cement com-pletely covers the area to be repaired.

AC 43.13-1B 9/8/98

Page 9-34 Par 9-42

(e) The inside patch should be ce-mented simultaneously with the application ofcement to the inside of the raft. Apply thesame number of coats as directed in para-graph 9 42b(2)(d) to the side of the patch thatis applied to the injured fabric of the raft. En-sure that each coat is thoroughly dry beforeapplying the next coat.

(f) To aid in adhesion, prior to ap-plying the patch, the inside area to be repairedand cemented surface of the patch should becleaned with a cloth moistened with rubbersolvent. The cement will then become tacky.

(g) Apply the patch. Fold the patchlengthwise in the shape of the letter “U” andinsert the patch between the torn edges of theinjury on the life rafts. Position the patch sothat the fabric at the end of the tear will coin-cide with a cross line and the center line on thepatch follows one edge of the torn fabric. At-tach one edge of the torn fabric along the cen-ter line on the patch.

(h) Inspect the repair for wrinkles.Working from the attached edge of the fabricto the edge of the patch, remove the wrinkleswith a stitcher. Lay the opposite edge of thetorn fabric on the patch so that it butts the edgeof the torn fabric that has already been appliedto the patch. Remove the wrinkles. Thor-oughly roll the patch with a 2 inch rubberroller.

NOTE: The surface under the patchshould be as smooth as possible so thatthe torn edge of the fabric may be at-tached to the patch instead of at-tempting to attach the patch to thefabric.

(i) Scatter the handful of talc that wasplaced inside the tube by grasping the sides ofthe flotation tube and pulling them apart.

(j) Prepare and attach the outsidepatch as outlined in “OUTSIDE PATCHES,”sub-paragraphs 9-42b(1)(a)-(e).

(k) Allow to cure for at least60 hours before performing leak tests andstoring.

(3) Seams and Tapes.

(a) Remove all old or dead cementfrom the area that will require recementing.Dampen the repair area with a solvent-moistened cloth; then roll or rub off the oldcement.

(b) Apply cement to the surface asoutlined in “OUTSIDE PATCHES,” sub-paragraph 9-42b(1)(a)-(e).

(c) Roll thoroughly with a roller toensure that all air pockets are removed and afirm bond is secured.

(d) Allow to dry and apply talc overthe seam as previously outlined.

(e) Allow to cure for at least 60 hoursbefore performing leak tests and storing.

9-43. LIFE PRESERVERS. Inflatable lifepreservers are subject to general deteriorationdue to aging. Experience has indicated thatsuch equipment may be in need of replacementat the end of 5 years due to porosity of the rub-ber-coated material. Wear of such equipmentis accelerated when stowed on board aircraftbecause of vibration which causes chafing ofthe rubberized fabric. This ultimately resultsin localized leakage. Leakage is also likely tooccur where the fabric is folded because sharpcorners are formed. When these corners are incontact with the carrying cases, or with adja-cent parts of the rubberized fabric, they tend towear through due to vibration.

9/8/98 AC 43.13-1B

Par 9-43 Page 9-35

Life preservers should be inspected in accor-dance with the manufacturer’s specification,unless climate, storage, or operational condi-tions indicate the need for more frequent in-spections (Ref: TSO-C13).

9-44. LIFE PRESERVER INSPECTION.Life preservers should be inspected at12-month intervals for cuts, tears, or otherdamage to the rubberized material. Check themouth valves and tubing for leakage, corro-sion, and deterioration. Remove the CO2 cyl-inder and check the discharge mechanism byoperating the lever to ascertain that the pin op-erates freely. Check the gaskets and valvecores of the cylinder container and the pullcord for deterioration. If no defects are found,inflate the preserver with air to a 2 psi pressureand allow to stand for 12 hours. If the pre-server still has adequate rigidity at the end ofthat time, deflate and fit with CO2 cylindershaving weights not less than that indicated onthem by the manufacturer. All cylinders madein accordance with joint Army/Navy Specifi-cation MIL-C-00601D are so stamped andhave a minimum permissible weight stampedon them. The use of such CO2 cylinders isrecommended. Having fitted the preserverwith an adequately-charged cylinder, mark thepreserver to indicate the date of inspection andpatch it to the container. It is recommendedthat the aforementioned procedure be repeatedevery 12-month period, utilizing the CO2 car-tridge for inflation. Carbon dioxide permeatesthe rubberized fabric at a faster rate than airand will indicate if the porosity of the materialis excessive. The following checks and in-spections should be completed:

a. Check for abrasions, chafing, andsoiling across folded cell areas and aroundmetal parts. Condemn the life preserver whenunsuitable conditions are found.

b. Check for separation of cell fabric andloose attachments along the edges of patchesand sealing tapes. Repair if practicable.

c. Check for deterioration in areas whereoil and grease are noted. Condemn deterio-rated cells. If deterioration is not noted, cleanthe areas with mild soap and water and rinsewith clear water.

d. Inspect the snaps and/or buckles toensure proper operation.

e. Inspect the instruction panel for read-ability.

f. Inspect all stitching for gaps, pulls, andtears.

g. Visually inspect the cell containers forsnags, cuts, loose stitching, and oil and greasespots. Repair or replace as necessary.

h. Inspect the hardware for rusted orbroken parts and cotter pins for damage. En-sure that pins are smooth and free of burrs.

i. Check the inflator discharge lever forproper operation. Move the inflator dis-charge lever slowly through a normal cycle ofoperation to ensure freedom of operation andto make certain that the piercing pin has suffi-cient movement to discharge the CO2 cylinder.The point of the pin should move past the sur-face of the gasket in the inflator. In the un-operated position, the end point should beslightly below the gasket surface.

j. Check the installation of the inflatorstem gaskets and check the stem caps fortightness. Ensure that the inflator is centeredon the stem.

k. Check rescue light. Inspect and test.

AC 43.13-1B 9/8/98

Page 9-36 Par 9-44

(1) Replace the battery if it shows anysigns of encrustation.

(2) Inspect for proper installation andphysical condition of the lamp, wire, and bat-tery.

(3) Check the light assembly for properoperation and water insulation and flotation.

(4) Pull the sealing plug (where appli-cable) from the battery. Let water flowthrough the open ports. Make sure the batteryis activated and power is supplied to the light.

(5) Fill out the inspection record andserviceable parts tag. Attach to the vest.

l. Deflate the life preserver and repack incontainer and secure.

m. The accessories listed below will berequired for all life preservers:

(1) One Recognition Light: Removewhen returning to serviceable or reparablestorage. Remove for replacement of defectivelight, repair, or salvage of preserver.

(2) One Recognition Light Battery:Remove when returning to serviceable or repa-rable storage.

n. Record the inspection data on datacards.

o. Life preserver inspected and foundsea worthy. Include the inspector’s signature.

p. Inspection record. Upon completionof 12-month inspection and tests, each flota-tion cell will be marked to indicate the date theinspection was accomplished. The inspectionstencil will consist of 1/8-inch letters and nu-merals and will be applied to the patches onthe cells (example: 4/3/97). To facilitate

determination of the next 12-month inspectionperiod, enter the date it is due in the blank be-side the word inspect on the inspection datacard provided in the inspection data pocket onthe cell container. Repack, close, and seal thecontainer. 9-45. REPAIR OF LIFE PRESERVERS.Leaks may be disclosed by immersion in soapywater. Repair leaks by the use of patches inaccordance with the recommendations of themanufacturer. Clean corroded metal parts andreplace missing or weakened lanyards. Lifepreservers which do not retain sufficient rigid-ity after the 12-hour period, because of generaldeterioration and porosity of the fabric, are be-yond economical repair and should be re-placed.

9-46. MISCELLANEOUS EQUIPMENT.

a. Parachutes. With reasonable care,parachutes can remain in service indefinitely.They should not be carelessly tossed about, leftin aircraft to become wet, or left where some-one may tamper with them. They should notbe placed where they may fall on oily floors orbe subject to acid fumes from adjacent batterychargers.

(1) When repacking is scheduled, tocomply with the 120-day requirement in Ti-tle 14 of the Code of Federal Regulation(14 CFR) part 105 section 105.43 a careful in-spection of the parachute shall be made by aqualified parachute technician (rigger). If re-pairs or replacements of parts are necessary tomaintain the airworthiness of the parachute as-sembly, such work must be done by the origi-nal parachute manufacturer or by a qualifiedparachute rigger, certificated in accordancewith 14 CFR, part 65.

(2) The lead seal should be inspectedperiodically to ensure the thread has not beenbroken. If broken, or broken and retied or

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Par 9-49 Page 9-37

appears to have been tampered with, the para-chute must be repacked by a properly certifiedrigger.

b. Safety Belts shall be of an approvedtype. All seat belts and restraint systems mustconform to standards established by the FAA.These standards are contained in TechnicalStandard Order TSO C22 for seat belts andTSO C114 for restraint systems.

(1) Safety belts eligible for installationin aircraft must be identified by the properTSO markings on the belt. Each safety beltmust be equipped with an approved metal tometal latching device. Airworthy type-certificated safety belts currently in aircraftmay be removed for cleaning and reinstalled.However, when a TSO safety belt is foundunairworthy, replacement with a newTSO-approved belt or harness is required.

(2) The webbing of safety belts, evenwhen mildew-proofed, is subject to deteriora-tion due to constant use, cleaning, and the ef-fects of aging. Fraying of belts is an indicationof wear, and such belts are likely to be unair-worthy because they can no longer hold theminimum required tensile load.

(3) Safety belts shall be repaired inaccordance with specifications approved by theresponsible FAA ACO.

9-47. OXYGEN SYSTEMS. The followinginstructions are to serve as a guide for the in-spection and maintenance of aircraft oxygensystems. The information is applicable to bothportable and permanently-installed equipment.

a. Aircraft Gaseous Oxygen Systems.The oxygen in gaseous systems is suppliedfrom one or more high- or low-pressure oxy-gen cylinders. Since the oxygen is compressedwithin the cylinder, the amount of pressure in-dicated on the system gauge bears a direct re-lationship to the amount of oxygen contained

in the cylinder. The pressure-indicating lineconnection is normally located between thecylinder and a pressure-reducing valve.

NOTE: Some of the gaseous oxygensystems do not use pressure-reducingvalves. The high pressure is reducedto a useable pressure by a regulator.This regulator is located between thehigh- and low-pressure system.

CAUTION: Oxygen rich environ-ments are dangerous.

b. Portable Oxygen Systems. The threebasic types of portable oxygen systems are:demand, pressure demand, and continuousflow. The components of these systems areidentical to those of a permanent installationwith the exception that some parts are minia-turized as necessary. This is done in order thatthey may be contained in a case or strappedaround a person’s shoulder. It is for this port-ability reason that special attention be given toassuring that any storage or security provisionfor portable oxygen equipment in the aircraft isadequate, in good condition, and accessible tothe user.

NOTE: Check portable equipmentincluding its security provisions fre-quently, since it is more susceptible topersonnel abuse than a permanently-installed system.

9-48. INSPECTION. Hands, clothing, andtools must be free of oil, grease, and dirt whenworking with oxygen equipment. Traces ofthese organic materials near compressed oxy-gen may result in spontaneous combustion,explosions, and/or fire.

a. Oxygen Tanks and Cylinders. Inspectthe entire exterior surface of the cylinder forindication of abuse, dents, bulges, and strapchafing.

(1) Examine the neck of cylinder forcracks, distortion, or damaged threads.

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Page 9-38 Par 9-44

(2) Check the cylinder to determine ifthe markings are legible.

(3) Check the date of the last hydro-static test. If the periodic retest date is past, donot return the cylinder to service until the testhas been accomplished.

(4) Inspect the cylinder mountingbracket, bracket hold-down bolts, and cylinder-holding straps for cracks, deformation, cleanli-ness, and security of attachment.

(5) In the immediate area where thecylinder is stored or secured, check for evi-dence of any types of interference, chafing, de-formation, or deterioration.

b. Lines and Fittings.

(1) Inspect oxygen lines for chafing,corrosion, flat spots and irregularities, i.e.,sharp bends, kinks, and inadequate security.

(2) Check fittings for corrosion aroundthe threaded area where lines are joined. Pres-surize the system and check for leaks. (Seeparagraph 9-49b(2)(d).)

CAUTION: In pressurizing the sys-tem, actuate the valve slowly to avoidsurging which could rupture the line.

c. Regulators, Valves, and Gauges.

(1) Examine all parts for cracks, nicks,damaged threads or other apparent damage.

(2) Actuate the regulator controls andthe valve to check for ease of operation.

(3) Determine if the gauge is function-ing properly by observing the pressure build-up and the return to zero when the system oxy-gen is bled off.

d. Masks and Hoses.

(1) Check the oxygen mask for fabriccracks and rough face seals. If the mask is afull-face model, inspect the glass or plastic forcleanliness and state of repair.

(2) When appropriate, with due regardto hygienic considerations, the sealing qualitiesof an oxygen mask may be tested by placing athumb over the connection at the end of themask tube and inhaling very lightly. Removethe thumb from the disconnect after each con-tinuous inhalation. If there is no leakage, themask will adhere tightly to the face during in-halation, and definite resistance to inhalationwill be noticeable.

(3) Flex the mask hose gently over itsentirety and check for evidence of deteriora-tion or dirt.

(4) Examine the mask and hose storagecompartment for cleanliness and general con-dition.

(5) If the mask and hose storage com-partment is provided with a cover or releasemechanism, thoroughly check the operation ofthe mechanism.

9-49. MAINTENANCE.

a. Oxygen Tanks, Cylinders, and Hold-Down Brackets.

(1) Remove from service any cylindersthat show signs of abuse, dents, bulges, cracks,distortion, damaged thread, or defects whichmight render them unsafe. Typical examples

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Par 9-49 Page 9-39

of oxygen cylinder damage are shown in fig-ure 9-14.

(2) When replacing an oxygen cylinder,be certain that the replacement cylinder is ofthe same size and weight as the one removed.

FIGURE 9-14. Oxygen cylinder damage.

NOTE: Cylinders having greaterweight or size will require strength-ened cylinder mounting brackets anda reevaluation to determine that thelarger or heavier cylinder will not in-terfere with adjacent systems, compo-nents, or structural members, and thatthe strength of attaching structure isadequate and any additional weightwill be computed into the aircraft’sweight and balance report.

(3) Replace or repair any cylindermounting brackets that show signs of wear.Visible cracks may be welded in accordance

with manufacturer’s standards. Replace thecylinder straps or clamps that show wear orabuse. For typical mounting bracket cracksand failure, see figure 9-15.

b. Lines and Fittings.

(1) Replace any oxygen line that ischafed, rusted, corroded, dented, cracked, orkinked.

(2) Clean oxygen system fittingsshowing signs of rusting or corrosion in thethreaded area. To accomplish this, use acleaner recommended by manufacturers ofoxygen equipment. Replace lines and fittingsthat cannot be cleaned.

(a) The high-pressure lines which arelocated between the oxygen bottle (outside theoxygen service filler) and the regulator arenormally fabricated from stainless steel orthick-wall, seamless copper alloy tubing. Thefittings on high-pressure lines are normally sil-ver brazed.

NOTE: Use silver alloys free of cad-mium when silver brazing. The use ofsilver brazing alloys, which containcadmium, will emit a poisonous gaswhen heated to a molten state. Thisgas is extremely hazardous to health ifinhaled.

FIGURE 9-15. Cylinder brackets and clamps.

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Page 9-40 Par 9-49

(b) The low-pressure lines extendfrom the pressure regulator to each passengerand crew oxygen outlet. These lines are fabri-cated from seamless aluminum alloy, copper,or flexible hose. Normally, flare- or flange-type connections are used.

CAUTION: Do not allow oil, grease,flammable solvent, or other combusti-bles such as lint or dust to come incontact with threads or any parts thatwill be exposed to pressurized oxygen.

(c) It is advisable to purge the oxygensystem any time work has been accomplishedon any of the lines and fittings. Use dry nitro-gen or dry air for purging the system. All openlines should be capped immediately afterpurging.

(d) When oxygen is being lost from asystem through leakage, a sequence of stepsmay be necessary to locate the opening. Leak-age may often be detected by listening for thedistinct hissing sound of escaping gas. If thischeck proves negative, it will be necessary tosoap-test all lines and connections with a cas-tile soap and water solution or specially com-pounded leak-test material. Make the solutionthick enough to adhere to the contours of thefittings. At the completion of the leakage test,remove all traces of the soap and water.

CAUTION: Do not attempt to tightenany connections while the system ischarged.

c. Regulators, Valves, and Gauges. Linemaintenance of oxygen regulators, valves, andgauges does not include major repair. Thesecomponents are precision made and their re-pair usually requires the attention of a repairstation or the manufacturer. Care must betaken when reinstalling these components to

ascertain if the threaded area is free of nicks,burrs, and contaminants that would prevent theconnections from sealing properly.

CAUTION: Do not use petroleum lu-bricants on these components.

d. Masks and Hoses.

(1) Troubleshooting. If a mask assem-bly is defective (leaks, does not allow breath-ing, or contains a defective microphone), it isadvisable to return the mask assembly to themanufacturer or a repair station.

(2) Maintenance Practice and Cleaning.

(a) Clean and disinfect the mask as-semblies after use, as appropriate.

NOTE: Use care to avoid damagingthe microphone assembly whilecleaning and sterilizing.

(b) Wash the mask with a mild soapsolution and rinse it with clear water.

(c) To sterilize, swab the mask thor-oughly with a gauze or sponge soaked in awater merthiolate solution. This solutionshould contain 1/5-teaspoon of merthiolateper 1 quart of water. Wipe the mask with aclean cloth and air dry.

(d) Replace the hose if it shows evi-dence of deterioration.

(e) Hoses may be cleaned in the samemanner as the mask.

(f) Observe that each mask breathingtube end is free of nicks, and that the tube endwill slip into the cabin oxygen receptacle withease and not leak.

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9-50. FUNCTIONAL TESTING AFTERREPAIR. Following repair, and before in-spection plates, cover plates, or upholsteringare replaced, test the entire system.

a. Open the cylinder valve slowly andobserve the pressure gauge on a high-pressuresystem. A pressure of approximately 1,800 psi(at 70 °F) should be indicated on the gauge.(Cylinder pressure will vary considerably withradical temperature changes.)

(1) Check the system by installing oneof the mask hose fittings (minus the mask) ineach of the cabin wall outlets to determinewhether there is a flow. If a demand mask isused, check by breathing through the maskand, if appropriate, clean the mask accordingto paragraph 9-49d.

(2) Check the complete system for leaksin accordance with the procedure outlined inparagraph 9-49b(2)(d).

(3) If leaks are found, close the cylindervalve and open an outlet to reduce the pressurein the system to zero.

b. The following checks may be made fora pressure drop check of the system.

(1) Open the cylinder valve and pres-surize the system. Observe the pressure gauge(a pressure of approximately 1,800 psi at 70 °Fshould be indicated). For the light weightICC 3HT 1850 cylinders, pressurize the systemto approximately 1,850 psi at 70 °F.

(2) Close the cylinder valve and waitapproximately 5 minutes for temperatures tostabilize.

(3) Record the pressure gauge readingand temperature and after 1 hour, record thepressure gauge reading and temperature again.

(4) A maximum pressure drop of100 psi is permissible.

NOTE: Conduct the above tests in anarea where changes of temperaturewill be less than 10 °°°°F. If a leak oc-curs during the 1-hour period, suit-able corrections would be required, orreconduct the test under conditions ofunvarying temperatures.

9-51. SERVICE OXYGEN CYLINDERS.REQUIREMENTS (Ref 49 CFR 173.34 e,16). Standard-weight cylinders must be hydro-static tested at the end of each 5-year period(10 years if it meets the requirements in 49CFR 173.34 e, 16). This is a Department ofTransportation (DOT) requirement. These-cylinders carry an ICC or DOT 3AA 1800classification and are suitable for the use in-tended.

Lightweight cylinders must be hydrostatictested every 3 years, and must be retired fromservice after 24 years or 4,380 pressurizations,whichever occurs first. These cylinders carryan ICC or DOT 3 HT 1850 classification andmust be stamped with the approval after beinginspected. (Ref. 49 CFR 173.34 e, 15).

CAUTION: Use only aviationbreathing oxygen when having theoxygen bottle charged.

a. Charging High-Pressure OxygenCylinders. The following are recommendedprocedures for charging high-pressure oxygencylinders from a manifold system, either per-manently-installed or trailer-mounted.

CAUTION: Never attempt to chargea low-pressure cylinder directly froma high-pressure manifold system orcylinder.

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(1) Inspection. Do not attempt tocharge oxygen cylinders if any of the followingdiscrepancies exist:

(a) Inspect for contaminated fittingson the manifold, cylinder, or outside fillervalve. If cleaning is needed, wipe with stabi-lized trichlorethylene and let air dry. Do notpermit the solvent to enter any internal parts.

(b) Check the hydrostatic test date ofthe cylinder. DOT regulations require ICC orDOT 3AA 1800 designation cylinders to behydrostatic tested to 5/3 their working pres-sure, every 5 years (10 years if they meet therequirements in 49 CFR 173.34,e, 16).

Cylinders bearing designation ICC orDOT 3HT 1850 (Ref. 49 CFR 173.34,e, 15)must be hydrostatic tested to 5/3 their workingpressure every 3 years, and retired from service24 years or 4,380 filling cycles after the date ofmanufacture, whichever occurs first.

(c) If the cylinder is completelyempty, do not charge. An empty cylinder mustbe removed, inspected, and cleaned beforecharging.

(2) Charging.

(a) Connect the cylinder valve outletor the outside filler valve to the manifold.

(b) Slowly open the valve of thecylinder to be charged and observe the pres-sure on the gauge of the manifold system.

(c) Slowly open the valve of the cyl-inder on the manifold system having the low-est pressure and allow the pressure to equalize.

(d) Close the cylinder valve on themanifold system and slowly open the valve ofthe cylinder having the next highest pressure.

Continue this procedure until the cylinder hasbeen charged in accordance with table 9-5.

(e) Close all valves on the manifoldsystem.

(f) Close the valve on the filled cyl-inder and remove the cylinder from the mani-fold.

(g) Using a leak detector, test forleakage around the cylinder valve threadedconnections. (If leakage is present, dischargethe oxygen and return the cylinder to the facil-ity for repair.)

(h) Let the cylinder stabilize for a pe-riod of at least 1 hour, and then recheck thepressure.

(i) Make any necessary adjustmentsin the pressure.

b. Charging of Low-Pressure OxygenSystems and Portables. For recharging alow-pressure aircraft oxygen system, or port-able cylinders, it is essential that the oxygentrailer or cart have a pressure-reducing regu-lator. Military types E-2 or C-1 reducingregulators are satisfactory. These types ofregulators reduce the large cylinder pressurefrom 2,000 psi to a line pressure of 450 psi.(A welding pressure-reducing regulator is notsatisfactory.)

CAUTION: When refilling the low-pressure system or portable cylinders,open the oxygen filler tank valveslowly to allow the system or portablecylinders to be filled at a slow rate.After the refilling operation is com-pleted, check for leaks with a leak de-tector. If a leak is detected, para-graph 9-49b(2)(d) should be referredto for corrective action.

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Par 9-51 Page 9-43 (and 9-44)

TABLE 9-5. Table of filling pressures.

Initial Temp(°°°° F)

Filling Pressure(psi)

0 1,65010 1,70020 1,72530 1,77540 1,82550 1,87560 1,92570 1,97580 2,00090 2,050100 2,100110 2,150120 2,200130 2,250

Initial Temperature-Refers to the ambient tem-perature in the filling room.

Filling Pressure-Refers to the pressure to whichaircraft cylinders should be filled. This table givesapproximations only, and assumes a rise in tem-perature of approximately 25 °F. due to the heat ofcompression. This table also assumes the aircraftcylinders will be filled as quickly as possible andthat they will only be cooled by ambient air, with nowater bath or other means of cooling being used.

Example: If ambient temperature is 70 °F, fill air-craft cylinders to approximately 1,975 psi-as closeto this pressure as the gauge may be read. Uponcooling, cylinders should have approximately1,850 psi pressure

9-52. 9-59. [RESERVED.]

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Par 9-60 Page 9-45

SECTION 4. CABIN INTERIOR

9-60. GENERAL. Only materials that areflash-resistant should be used in cabininteriors. The requirements related to fireprotection qualities of cabin interior materialsare specified in CAR 3.388, fire precautions or14 CFR part 23, section 23.853 compartmentinteriors

9-61. CAR-3 AIRCRAFT INTERIOR.The requirement for an interior of a CAR-3aircraft that is used only in 14 CFR, part 91operations, where smoking is not permitted, isthat the materials shall be flash-resistant.(Reference CAR-3.388.)

a. For compartments in CAR-3 aircraftwhere smoking is permitted, the wall andceiling linings, the covering of allupholstering, floors, and furnishings shall beflame-resistant. Such compartments should beequipped with an adequate number of self-contained ash trays. All other compartmentsshall be placarded against smoking. (Refer toCAR-3.388.)

(1) If fabric is bought in bulk torefurbish the interior, seats, and ceiling linersfor a CAR-3 aircraft used in part 91operations, a manufacturer’s statement,declaring that the material meets the AmericanSociety for Testing and Materials (ASTM) orsimilar national standard for either flashresistance or flame resistance, would beacceptable, but only for a CAR-3 aircraftinstallation. (Refer to 14 CFR part 43,section 43.13(a).) A manufacturer’s statementis acceptable due to neither the CivilAeronautics Administration (CAA) nor theFederal Aviation Administration (FAA) havingpublished an FAA fire standard for either flashor flame resistance for interior materials forCAR-3 aircraft. Since the FAA would acceptand recognize a national

standard, the mechanic would reference themanufacturer’s statement and the nationalstandard that the material meets in theaircraft’s maintenance records.

(2) If an annual inspection is performedon a CAR-3 aircraft with a new interior andthere is no mention of a manufacturer’sstatement that the fabric is flash or flameresistant as applicable, the possibility existsthat the fabric is an unapproved part. Themechanic should take the necessary steps toensure that the fabric meets or exceeds theASTM or national standards. (Refer to14 CFR part 23, appendix F.)

(3) If an FAA-approved STC interior kitis installed in a CAR-3 aircraft, and thematerial and fabric in the kit are PMA or TSOapproved, the mechanic should include theSTC number in block 8 of FAA Form 337.

b. It is recommended that for all CAR-3interiors to use only fabric and materials thatmeets the more stringent requirements ofpart 23, appendix F.

9-62. PART 23 AIRCRAFT INTERIOR.Materials used in part 23 aircraft interiors mustmeet the requirements of section 23.853, andthe burn test requirements called out in part 23,appendix F.

a. If the fabric is bought in bulk torefurbish a part 23 aircraft then the fabric mustmeet the part 23 burn requirements. A burntest would have to be done on samples of thematerial and fabrics by an approved and ratedFAA Repair Station. That FAA Repair Stationwould certify that all the material and fabricsmeet part 23, appendix F requirements. Themechanic would include that repair station’sstatement in the aircraft’s records.

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b. If STC-approved interior kit witheither PMA or TSO-approved materials for apart 23 aircraft is bought, the mechanic wouldonly have to reference the STC number onFAA Form 337 and the aircraft’s records.Part 23, appendix F would not be required.

c. If an annual inspection is to beperformed on a part 23 aircraft in which anew interior was installed, but the aircraft’srecords do not reflect that a burn test wasperformed on the interior’s materials andfabric by an FAA Approved Repair Station, orthere is no mention of an STC or FAAForm 337 in the aircraft records, then a burntest that meets, part 23, appendix F must beaccomplished before the aircraft is approvedfor return to service.

9-63. SOURCE OF INFORMATION. Ifinformation regarding the original or properlyaltered fire protection qualities of certain cabininterior materials is not available, requests forthis information should be made to the aircraftmanufacturer or the local FAA regional office,specifying the model aircraft and the aircraftmanufacturer. The date the aircraft wasmanufactured or the serial number, and the14 CFR part under which the aircraft isoperated (i.e., CAR-3, 14 CFR part 91, orpart 121, etc.).

9-64. UPHOLSTERY AND/OR BELTS.Upholstery and/or belts that have been washedmay lose some or all of their fire-resistantqualities. Unless the soap is completelyremoved from the cloth, the strength of thematerial may be significantly reduced. Consultthe manufacturer to determine how to maintainthe fire-resistant qualities.

9-65. 9-70. [RESERVED.]

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CHAPTER 10. WEIGHT AND BALANCE

SECTION 1 TERMINOLOGY

10-1. GENERAL. The removal or additionof equipment results in changes to the center ofgravity (c.g.). The empty weight of the air-craft, and the permissible useful load are af-fected accordingly. Investigate the effects ofthese changes, since the aircraft flight charac-teristics may be adversely affected. Informa-tion on which to base the record of weight andbalance changes to the aircraft may be ob-tained from the pertinent Aircraft Specifica-tions, Type Certificate Data Sheet (TCDS),prescribed aircraft operating limitations, air-craft flight manual, aircraft weight and balancereport, and maintenance manual. Removal ofstandard parts with negligible weight or addi-tion of minor items of equipment such as nuts,bolts, rivets, washers, and similar standardparts of negligible weight on fixed-wing air-craft do not require a weight and balancecheck. Rotorcraft are, in general, more criticalwith respect to control with changes in the c.g.position. Refer to the procedures and instruc-tions in that particular model’s maintenance orflight manual.

10-2. TERMINOLOGY. The followingterminology is used in the practical applicationof weight and balance control.

a. Maximum Weight. The maximumweight is the maximum authorized weight ofthe aircraft and its contents as listed in thespecifications.

b. Empty Weight. The empty weight ofan aircraft includes all operating equipmentthat has a fixed location and is actually in-stalled in the aircraft. It includes the weight ofthe airframe, powerplant, required equipment,optional and special equipment, fixed ballast,full engine coolant, hydraulic fluid, residualfuel, and oil. Additional information regarding

fluids that may be contained in the aircraftsystems and must be included in the emptyweight will be indicated in the pertinent Air-craft Specifications or TCDS.

c. Negligible Weight Change is anychange of one pound or less for aircraft whoseweight empty is less than 5,000 pounds; twopounds or less for aircraft whose weight emptyis more than 5,000 and 50,000 pounds; andfive pounds or less for aircraft whose weightempty is more than 50,000 pounds. Negligiblec. g. change is any change of less than 0.05%MAC for fixed wing aircraft, 0.2 percent of themaximum allowable c. g. range for rotary wingaircraft.

d. Useful Load. The useful load is theempty weight subtracted from the maximumweight of the aircraft. This load consists of thepilot, crew (if applicable), maximum oil, fuel,passengers, and baggage unless otherwisenoted.

e. Weight Check. The weight check con-sists of checking the sum of the weights of allitems of useful load against the authorized use-ful load (maximum weight less empty weight)of the aircraft.

f. Datum. The datum is an imaginaryvertical plane from which all horizontal meas-urements are taken for balance purposes withthe aircraft in level flight attitude. The datumis indicated in most Aircraft Specifications orTCDS. On some of the older aircraft, whenthe datum is not indicated, any convenient da-tum may be selected. Once the datum is se-lected, all moment arms and the location of thepermissible c.g. range must be taken with ref-erence to it. Examples of typical locations ofthe datum are shown in figure 10-1.

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g. Arm (or Moment Arm). The arm (ormoment arm) is the horizontal distance ininches from the datum to the c.g. of an item.The algebraic sign is plus ( + ) if measured aft

of the datum, and minus ( - ) if measured for-ward of the datum. Examples of plus and mi-nus arms are shown in figure 10-2.

FIGURE 10-1. Typical datum locations.

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FIGURE 10-2. Illustration of arm (or moment arm).

h. Moment. The moment is the productof a weight multiplied by its arm. The momentof an item about the datum is obtained bymultiplying the weight of the item by its hori-zontal distance from the datum. A typicalmoment calculation is given in figure 10-3.

i. Center of Gravity. The c.g. is a pointabout which the nose-heavy and tail-heavymoments are exactly equal in magnitude. Ifthe aircraft is suspended from the c.g., it willnot have a tendency to pitch in either direction(nose up or down). The weight of the aircraft(or any object) may be assumed to be concen-trated at its c.g. (See figure 10-3.)

j. Empty Weight Center of Gravity.The empty weight c.g. is the c.g. of an aircraftin its empty weight condition, and is an essen-tial part of the weight and balance record.Formulas for determining the c.g. for tail andnosewheel type aircraft are given in fig-ure 10-4. Typical examples of computing theempty weight and empty weight c.g. for air-craft are shown in figures 10-5 and 10-6.

k. Empty Weight Center of GravityRange. The empty weight c.g. range is deter-mined so that the empty weight c.g. limits willnot be exceeded under standard specificationsloading arrangements. Calculations as out-lined in paragraph 10-16 should be completedwhen it is possible to load an aircraft in amanner not covered in the Aircraft Specifica-tions or TCDS (extra tanks, extra seats, etc.).The empty weight c.g. range, when applicable,is listed in the Aircraft Specifications orTCDS. Calculation of empty weight c.g. isshown in figures 10-5 and 10-6.

l. Operating Center of Gravity Range.The operating c.g. range is the distance be-tween the forward and rearward c.g. limits in-dicated in the pertinent Aircraft Specificationsor TCDS. These limits are determined for themost forward and most rearward loaded c.g.positions at which the aircraft meets the re-quirements of Title 14 of the Code of FederalRegulation (14 CFR). The limits are indicatedin the specifications in either percent of meanaerodynamic chord (MAC) or inches from the

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FIGURE 10-3. Example of moment computation.

datum. The c.g. of the loaded aircraft must bewithin these limits at all times as illustrated infigure 10-7.

m. Mean Aerodynamic Chord (MAC).The MAC is established by the manufacturerwho defines its leading edge and its trailingedge in terms of inches from the datum. Thec.g. location and various limits are then ex-pressed in percentages of the chord. The

location and dimensions of the MAC can befound in the Aircraft Specifications, theTCDS, the aircraft flight manual, or the air-craft weight and balance report.

n. Weighing Point. If the c.g. location isdetermined by weighing, it is necessary to ob-tain horizontal measurements between thepoints on the scale at which the aircraft’sweight is concentrated. If weighed using

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FIGURE 10-4. Empty weight center of gravity formulas.

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FIGURE 10-5. Empty weight and empty center of gravity - tail-wheel type aircraft.

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FIGURE 10-6. Empty weight and empty weight center of gravity - nosewheel-type aircraft.

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FIGURE 10-7. Operating center of gravity range.

scales under the landing gear tires, a verticalline passing through the centerline of the axlewill locate the point on the scale at which theweight is concentrated. This point is called the“weighing point.” Other structural locationscapable of supporting the aircraft, such as jackpads on the main spar, may also be used if theaircraft weight is resting on the jack pads. In-dicate these points clearly in the weight andbalance report when used instead of the land-ing gear. Typical locations of the weighingpoints are shown in figure 10-8.

o. Zero Fuel Weight. The maximumpermissible weight of a loaded aircraft (pas-sengers, crew, cargo, etc.) less its fuel is zerofuel weight. All weights in excess of maxi-mum zero fuel weight must consist of usablefuel.

p. Minimum Fuel. The minimum fuel forbalance purposes is 1/12 gallon per maximum-

except-take-off horsepower (METO). Mini-mum fuel is the maximum amount of fuelwhich can be used in weight and balance com-putations when low fuel might adversely affectthe most critical balance conditions. To de-termine the weight of fuel in pounds divide theMETO horsepower by two.

q. Full Oil. The full oil is the quantity ofoil shown in the Aircraft Specifications orTCDS as oil capacity. Use full oil as thequantity of oil when making the loaded weightand balance computations.

r. Tare. The weight of chocks, blocks,stands, etc., used when weighing aircraft iscalled tare and is included in the scale read-ings. Tare is deducted from the scale readingat each respective weighing point when tare isinvolved, to obtain the actual aircraft weight.

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Par 10-2 Page 10-9 (and 10-10)

FIGURE 10-8. Weighing point centerline.

10-3. 10-13. [RESERVED.]

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Par 10-14 Page 10-11

SECTION 2 WEIGHING PROCEDURES

10-14. GENERAL. Weighing proceduresmay vary with the aircraft and the type ofweighing equipment employed. The weighingprocedures contained in the manufacturer’smaintenance manual should be followed foreach particular aircraft.

10-15. PROCEDURES. Accepted proce-dures when weighing an aircraft are:

a. Remove excessive dirt, grease, mois-ture, etc., from the aircraft before weighing.

b. Weigh the aircraft inside a closedbuilding to prevent error in scale reading dueto wind.

c. Determine the empty weight c. g. byplacing the aircraft in a level flight attitude.

d. Have all items of equipment that areincluded in the certificated empty weight re-port installed in the aircraft when weighing.These items of equipment are a part of the cur-rent weight and balance report.

e. The scales should have a current cali-bration before weighing begins. Zero and usethe scales in accordance with the scale manu-facturer’s instructions. Platform scales andsuitable support for the aircraft, if necessary,are usually placed under the wheels of a land-plane, the keel of a seaplane float, or the skisof a skiplane. Other structural locations capa-ble of supporting the aircraft, such as jackpads, may be used. Clearly indicate thesepoints and the alternate equipment used in theweight and balance report.

f. Drain the fuel system until the quantityindicator reads zero or until the tanks areempty with the aircraft in level flight attitude,unless otherwise noted in the TCDS or AircraftSpecifications. The amount of fuel remaining inthe tank, lines, and engine is termed residual fuel

and is to be included in the empty weight. In spe-cial cases, the aircraft may be weighed withfull fuel in tanks provided a definite means ofdetermining the exact weight of the fuel isavailable.

g. The oil system should be filled to thequantity noted in the TCDS or Aircraft Speci-fications.

NOTE: On Civil Aeronautics Regula-tions (CAR-3) Certified Aircraft, theweight of the oil was subtractedmathematically to get the emptyweight. In 14 CFR, part 23 aircraft,the weight of the oil is included in theempty weight.

When weighed with full oil, actual emptyweight equals the actual recorded weight lessthe weight of the oil in the oil tank( oil weight= oil capacity in gallons x 7.5 pounds). Indi-cate on all weight and balance reports whetherweights include full oil or oil drained. (See fig-ure 10-9.)

h. Do not set brakes while taking scalereading.

i. Note any tare reading when the aircraftis removed from the scales.

10-15a. REPAIRS AND ALTERATIONSare the major sources of weight changes, and itis the responsibility of the aircraft mechanicmaking any repairs or alteration to know theweight and location of these changes, and tocompute the new CG and record the newempty (EW) weight and EWCG data in theaircraft flight manual.

10-15b. ANNUAL OR 100-HOUR IN-SPECTION. After conducting an annual or100-hour inspection, the aircraft mechanic

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Page 10-12 Par 10-16

must ensure the weight and balance data in theaircraft records is current and accurate.

10-16. WEIGHT AND BALANCE COM-PUTATIONS. It is often necessary aftercompleting an extensive alteration to establishby computation that the authorized weight andc.g. limits as shown in the TCDS and AircraftSpecifications are not exceeded. Paragraphb(2) explains the significance of algebraicsigns used in balance computations.

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Par 10-16 Page 10-12a (and 10-12b)

EMPTY WEIGHT AND EMPTY WEIGHT CENTER OF GRAVITY(when aircraft is weighed with oil)

GIVEN: Aircraft as weighed with full oil -------------------------------------------------------------- 1186 lbs. Center of gravity -------------------------------------------------------------------------------- 9.7” Full oil capacity 9 qts. -------------------------------------------------------------------------- 17 lbs.

SOLVING:Weight # x Arm” = Moment “#

Aircraft as weighed + 1186 + 9.7 + 11504Less oil - 17 - 49.0 + 833Total + 1169(A) + 12337(B)

Empty Weight (A) = 1169 pounds

Empty Weight Center of Gravity B = 12337 = + 10.6”A 1169

FIGURE 10-9. Empty weight and empty weight center of gravity when aircraft is weighed with oil.

a. The TCDS or Aircraft Specificationscontain the following information relating tothe subject:

(1) Center of gravity range.(2) Empty weight c.g. range when ap-

plicable.(3) Leveling means.(4) Datum.(5) Maximum weights.(6) Number of seats and arm.

(7) Maximum baggage and arm.(8) Fuel capacity and arm.(9) Oil capacity and arm.(10) Equipment items and arm.

b. The TCDS do not list the basic re-quired equipment prescribed by the applicableairworthiness regulations for certification. Re-fer to the manufacturer’s equipment list forsuch information.

(1) Unit weight for weight and balancepurposes.

Gasoline ----------- 6 pounds per U.S. gal.Turbine Fuel ------ 6.7 pounds per U.S. gal.Lubricating oil ---- 7.5 pounds per U.S. gal.Crew and

passengers ----- 170 pounds per person.

(2) It is important to retain the properalgebraic sign (+ or -) through all balancecomputations. For the sake of uniformity inthese computations, visualize the aircraft withthe nose to the left. In this position any arm tothe left (forward) of the datum is “minus” andany arm to the right (rearward) of the datum is“plus.” Any item of weight added to the air-craft either side of the datum is plus weight,any weight item removed is a minus weight.When multiplying weights by arms, the answeris plus if the signs are the same, and minus ifthe signs are different. The following combi-nations are possible:

Items added forward of the datum-

( + ) weight x ( - ) arm = ( - ) moment.

Items added to the rear of the datum-

( + ) weight x ( + ) arm = ( + ) moment.

Items removed forward of the datum-

( - ) weight x ( - ) arm = ( + ) moment.

Items removed rear of the datum-

( - ) weight x ( + ) arm = ( - ) moment.

(3) The total weight of the airplane isequal to the weight of the empty aircraft plusthe weight of the items added minus theweight of the items removed.

(4) The total moment of the aircraft isthe algebraic sum of the empty weight momentof the aircraft and all of the individual mo-ments of the items added and/or removed.

10-17. WEIGHT AND BALANCE EX-TREME CONDITIONS. The weight andbalance extreme conditions represent themaximum forward and rearward c.g. positionfor the aircraft. Include the weight and balancedata information showing that the c.g. of theaircraft (usually in the fully loaded condition)falls between the extreme conditions.

a. Forward Weight and Balance Check.When a forward weight and balance check ismade, establish that neither the maximumweight nor the forward c.g. limit listed in theTCDS and Aircraft Specifications are ex-ceeded. To make this check, the following in-formation is needed:

(1) The weights, arms, and moment ofthe empty aircraft.

(2) The maximum weights, arms, andmoments of the items of useful load that arelocated ahead of the forward c.g. limit.

(3) The minimum weights, arms, andmoments of the items of useful load that arelocated aft of the forward c.g. limit. A typicalexample of the computation necessary to makethis check, using this data, is shown in fig-ure 10-10.

b. Rearward Weight and BalanceCheck. When a rearward weight and balancecheck is made, establish that neither themaximum weight nor the rearward c.g. limitlisted in the TCDS and Aircraft Specificationsare exceeded. To make this check, the fol-lowing information is needed:

(1) The weight, arms, and moments ofthe empty aircraft.

(2) The maximum weights, arms, andmoments of the items of useful load that arelocated aft of the rearward c.g. limit.

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Par 10-16 Page 10-13

TO CHECK: MOST FORWARD WEIGHT AND BALANCE EXTREME.

GIVEN:Actual empty weight of the aircraft --------------------------------------------------------------------------1169#Empty weight center of gravity-------------------------------------------------------------------------------+ 10.6”*Maximum weight----------------------------------------------------------------------------------------------2100#*Forward C.G.. limit -------------------------------------------------------------------------------------------+ 8.5”*Oil capacity, 9 qts. --------------------------------------------------------------------------------------------17# at -49”*Pilot in farthest forward seat equipped withcontrols (unless otherwise placarded) -----------------------------------------------------------------------170# at +16”*Since the fuel tank is located to the rear of theforward C.G. limit, minimum fuel should be included.METO HP = 165 = 13.75 gal. x 6#--------------------------------------------------------------------------83# at +22” 12 12* Information should be obtained from the aircraft specification.Note: Any items or passengers must be used if they are located ahead of the forward C.G. limit. Full fuel must be used if the tank is located ahead of the forward C.G. limit.

CHECK OF FORWARD WEIGHT AND BALANCE EXTREMEWeight (#) x Arm (“) = Moment (“#)

Aircraft empty + 1169 + 10.6 + 12391Oil + 17 - 49 - 833Pilot + 170 + 16 + 2720Fuel + 83 + 22 + 1826Total + 1439 (TW) + 16104 (TM)

Divide the TM (total moment) by the TW (total weight) to obtain the forward weight and balance extreme.TM = 16104 = + 11.2”TW 1439

Since the forward C.G. limit and the maximum weight are not exceeded, the forward weight and balanceextreme condition is satisfactory.

FIGURE 10-10. Example of check of most forward weight and balance extreme.

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Page 10-14 Par 10-17

(3) The minimum weights, arms, andmoments of the items of useful load that arelocated ahead of the rearward c.g. limit. Atypical example of the computation necessaryto make this check, using this data, is shown infigure 10-11.

10-18. LOADING CONDITIONSAND/OR PLACARDS. If the followingitems have not been covered in the weight andbalance extreme condition checks and are notcovered by suitable placards in the aircraft, ad-ditional computations are necessary. Thesecomputations should indicate the permissibledistribution of fuel, passengers, and baggagethat may be carried in the aircraft at any onetime without exceeding either the maximumweight or c.g. range. The conditions to checkare:

a. With full fuel, determine the number ofpassengers and baggage permissible.

b. With maximum passengers, determinethe fuel and baggage permissible.

c. With maximum baggage, determinethe fuel and the number and location of pas-sengers.

d. Examples of the computations for theabove items are given in figures 10-12, 10-13,and 10-14 respectively. The above cases aremainly applicable to the lighter type personalaircraft. In the case of the larger type transportaircraft, a variety of loading conditions is pos-sible and it is necessary to have a loadingschedule.

10-19. EQUIPMENT LIST. A list of theequipment included in the certificated emptyweight may be found in either the approvedaircraft flight manual or the weight and bal-ance report. Enter into the weight and balance

report all required, optional, and specialequipment installed in the aircraft at time ofweighing and/or subsequent equipmentchanges.

a. Required equipment items are listed inthe pertinent Aircraft Specifications.

b. Optional equipment items are listed inthe pertinent Aircraft Specifications and maybe installed in the aircraft at the option of theowner.

c. Special equipment is any item not cor-responding exactly to the descriptive informa-tion in the Aircraft Specifications. This in-cludes items such as emergency locator trans-mitter (ELT), tail or logo lights, instruments,ashtrays, radios, navigation lights, and carpets.

d. Required and optional equipmentmay be shown on the equipment list with ref-erence to the pertinent item number listed inthe applicable specifications only when theyare identical to that number item with refer-ence to description, weight, and arm given inthe specifications. Show all special equipmentitems with reference to the item by name,make, model, weight, and arm. When the armfor such an item is not available, determine byactual measurement.

10-20. EQUIPMENT CHANGE. The per-son making an equipment change is obligatedto make an entry on the equipment list indi-cating items added, removed, or relocated withthe date accomplished, and identify himself byname and certificate number in the aircraft re-cords. Examples of items so affected are theinstallation of extra fuel tanks, seats, and bag-gage compartments. Figure 10-15 illustratesthe effect on balance when equipment itemsare added within the acceptable c.g. limits andfore and aft of the established c.g. limits.

9/8/98 AC 43.13-1B

Par 10-17 Page 10-15

TO CHECK: MOST REARWARD WEIGHT AND BALANCE EXTREME.

GIVEN:Actual empty weight of the aircraft --------------------------------------------------------------------------1169#Empty weight center of gravity-------------------------------------------------------------------------------10.6”*Maximum weight----------------------------------------------------------------------------------------------2100#*Rearward C.G.. limit------------------------------------------------------------------------------------------21.9”*Oil capacity, 9 qts. --------------------------------------------------------------------------------------------17# at -49”*Baggage, placarded do not exceed 100 lbs ---------------------------------------------------------------100# at +75.5”*Two passengers in rear seat, 170# x 2 ---------------------------------------------------------------------340# at +48”*Pilot in most rearward seat equipped withcontrols (unless otherwise placarded) -----------------------------------------------------------------------170# at +16”*Since the fuel tank is located aft of therearward C.G. limit full fuel must be used------------------------------------------------------------------240# at +22”

* Information should be obtained from the aircraft specification.Note: If fuel tanks are located ahead of the rearward C.G. limit minimum fuel should be used.

CHECK OF REARWARD WEIGHT AND BALANCE EXTREMEWeight (#) x Arm (“) = Moment (“#)

Aircraft empty + 1169 + 10.6 + 12391Oil + 17 - 49 - 833Pilot (1) + 170 + 16 + 2720Passenger (2) + 340 + 48 + 16320Fuel (40 gals.) + 240 + 22 + 5280Baggage + 100 + 75.5 + 7550Total + 2036 (TW) + 43428 (TM)

Divide the TM (total moment) by the TW (total weight) to obtain the rearward weight and balance extreme.TM = 43428 = + 21.3”TW 2036

Since the rearward C.G. limit and the maximum weight are not exceeded, the rearward weight and balance ex-treme condition is satisfactory.

FIGURE 10-11. Example of check of most rearward weight and balance extreme.

AC 43.13-1B 9/8/98

Page 10-18 Par 10-20

EXAMPLE OF THE DETERMINATION OF THE NUMBER OF PASSENGERS AND BAGGAGEPERMISSIBLE WITH FULL FUEL

GIVEN:Actual empty weight of the aircraft ------------------------------------------------------------------------- 1169#Empty weight center of gravity ------------------------------------------------------------------------------ 10.6”Maximum weight----------------------------------------------------------------------------------------------- 2100#Datum is leading edge of the wingForward center of gravity limit ------------------------------------------------------------------------------ 8.5”Rearward center of gravity limit ----------------------------------------------------------------------------- 21.9”Oil capacity, 9 qts.; show full capacity --------------------------------------------------------------------- 17# at -49”Baggage, maximum-------------------------------------------------------------------------------------------- 100# at +75.5”Two passengers in rear seat, 170# x 2 ---------------------------------------------------------------------- 340# at +48”Pilot in most rearward seat equipped withcontrols (unless otherwise placarded) ---------------------------------------------------------------------- 170# at +16”Full fuel, 40 gals. x 6#----------------------------------------------------------------------------------------- 240# at +22”

Weight (#) x Arm (“) = Moment (“#)Aircraft empty + 1169 + 10.6 + 12391Oil + 17 - 49 - 833Full Fuel + 240 + 22 + 5280Passengers 2 rear + 340* + 48 +16320Pilot + 170 + 16 + 2720Baggage + 100 + 75.5 + 7550Total + 2036 (TW) + 43428 (TM)

Divide the TM (total moment) by the TW (total weight) to obtain the loaded centerof gravity.

TM = 43428 = + 21.3”TW 2036

The above computations show that with full fuel, 100 pounds of baggage and twopassengers in the rear seat may be carried in this aircraft without exceeding eitherthe maximum weight or the approved C. G. range.

This condition may be entered in the loading schedule as follows:

GALLONS OF FUEL NUMBER OF PASSENGERS POUNDS OF BAGGAGEFull 2 Rear 100

* Only two passengers are listed to prevent the maximum weight of 2100 lbs. from being exceeded.

FIGURE 10-12. Loading conditions: determination of the number of passengers and baggage permissiblewith full fuel.

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Par 10-20 Page 10-17

EXAMPLE OF THE DETERMINATION OF THE POUNDS OF FUEL AND BAGGAGE PERMISSIBLEWITH MAXIMUM PASSENGERS

Weight (#) x Arm (“) = Moment (“#)Aircraft empty + 1169 + 10.6 + 12391Oil + 17 - 49 - 833Pilot + 170 + 16 + 2720Passenger (1) front + 170 + 16 + 2720Passenger (2) rear + 340 + 48 +16320Fuel (39 gals.) + 234 + 22 + 5148Baggage ---- ---- ----Total + 2100 + 38466

Divide the TM (total moment) by the TW (total weight) to obtain the loaded centerof gravity.

TM = 38466 = + 18.6”TW 2100

The above computations show that with the maximum number of passengers, 39gallons of fuel and zero pounds of baggage may be carried in this aircraft withoutexceeding either the maximum weight or the approved C. G. range.

This condition may be entered in the loading schedule as follows:

GALLONS OF FUEL NUMBER OF PASSENGERS POUNDS OF BAGGAGE*Full *2 Rear * 100 39 1(F) 2(R) None

* Conditions as entered from Figure 10-12 (F) Front seat (R) Rear seat

FIGURE 10-13. Loading conditions: determination of the fuel and baggage permissible with maximum passengers.

AC 43.13-1B 9/8/98

Page 10-18 Par 10-20

EXAMPLE OF THE DETERMINATION OF THE FUEL AND THE NUMBER AND LOCATION OFPASSENGERS PERMISSIBLE WITH MAXIMUM BAGGAGE

Weight (#) x Arm (“) = Moment (“#)Aircraft empty + 1169 + 10.6 + 12391Oil + 17 - 49 - 833Pilot + 170 + 16 + 2720Passenger (1) rear + 170 + 48 + 8160Passenger (1) front + 170 + 16 + 2720Fuel (40 gals.) + 240 + 22 + 5280Baggage + 100 + 75.5 + 7550Total + 2036 + 37988

Divide the TM (total moment) by the TW (total weight) to obtain the loaded centerof gravity.

TM = 37988 = + 18.7TW 20366

The above computations show that with maximum baggage, full fuel and 2 passen-gers (1 in the front seat and 1 in the rear seat) may be carried in this aircraft withoutexceeding either the maximum weight or the approved C. G. range.

This condition may be entered in the loading schedule as follows:

GALLONS OF FUEL NUMBER OF PASSENGERS POUNDS OF BAGGAGE*Full *2 Rear * 100** 39 *1(F) 2(R) **None Full 1(F) 1(R) Full

* Conditions as entered from Figure 10-12** Conditions as entered from Figure 10-13 (F) Front seat (R) Rear seat

FIGURE 10-14. Loading conditions: determination of the fuel and the number and location of passengerspermissible with maximum baggage.

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Par 10-20 Page 10-19

FIGURE 10-15. Effects of the addition of equipment items on balance.

Moment computations for typical equipmentchanges are given in figure 10-16 and are alsoincluded in the sample weight and balancesheet in figure 10-18.

10-21. SAMPLE WEIGHT AND BAL-ANCE REPORT. Suggested methods oftabulating the various data and computationsfor determining the c.g., both in the emptyweight condition and the fully loaded condi-tion, are given in figures 10-17 and 10-18, re-spectively, and represent a suggested means ofrecording this information. The data presentedin figure 10-17 have previously been computed

in figures 10-10 and 10-11 for the extremeload conditions and figure 10-16 for equip-ment change, and represents suggested meansof recording this information.

10-22. INSTALLATION OF BALLAST.Ballast is sometimes permanently installed forc.g. balance purposes as a result of installationor removal of equipment items and is not usedto correct a nose-up or nose-down tendency ofan aircraft. It is usually located as far aft or asfar forward as possible in order to bring the

AC 43.13-1B 9/8/98

Page 10-20 Par 10-20

c.g. position within acceptable limits with aminimum of weight increase. Permanent bal-last is often lead plate wrapped around andbolted to the fuselage primary structure (e.i.,tail-post, longerons, or bulkhead members).Permanent ballast invariably constitutes a con-centrated load; therefore, the strength of thelocal structure and the attachment of the ballastthereto should be investigated for the designloading conditions pertinent to that particularaircraft. Placard permanent ballast with Per-manent ballast - do not remove. It is not

desirable to install permanent ballast by pour-ing melted lead into the tail-post or longeronsdue to difficulties that may be encountered insubsequent welding repair operations. Itshould be noted that the installation of perma-nent ballast results in an increase of aircraftempty weight. See figure 10-19 for ballastcomputation. The local strength of the com-partment in which the ballast is carried and theeffect of the ballast on aircraft weight and bal-ance should be investigated when disposableballast is carried.

FIGURE 10-16. Example of moment and weight changes resulting from equipment changes.

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Par 10-22 Page 10-23

MAKE MA-700 MODEL A SERIAL # 0000 REGISTRATION # N1234 .DATUM IS leading edge of wing .

COMPUTE AS FOLLOWS IF AIRCRAFT WEIGHED

1. Leveling means: level top longeron between front and rear seats.2. Main wheel weighing point is located ( “FORWARD) (+ 3 “ AFT) of datum.3. Actual measured distance from the main weight point centerline to the tail (or nose) point centerline 222 “.4. Oil over and above “ZERO” tank reading = (a. ---- Gals.) (b. ---- Lbs.) (c. ---- In.)

ACTUAL EMPTY WEIGHT Weight Point Scale Reading - Tare = Net Weight5. Right 564 0 5646. Left 565 0 5657. Tail 67 27 408. Nose ---- ---- -----9. Total Net Weight X X 1169

CENTER OF GRAVITY AS WEIGHED10. C.G. relative to main wheel weighing point: (a) Tail wheel airc. (Item 3, 222) x (Item 7, 40 ) = + 7.6 = C.G.

(Item 9, 1169)

(b) Nose wheel airc. (Item 3 ----) x (Item 8 ---- ) = = C.G. (Item 9 ---- )

11. C.G. relative to datum: (a) Tail wheel airc. (Item 10a, + 7.6) added to (Item 2, + 3) = +10.6” = C.G. (b) Nose wheel airc. (Item 10b, ) added to (Item 2, ) = = C.G.

COMPUTE IF AIRCRAFT WEIGHED WITH OIL (Item 4) Weight x Arm = Moment

AircraftLess Oil

(9)(4b)

(11)(4c)

Empty Totals (a) X (b)

(b) ------------------- = (c) ------------------“ = Empty weight C.G.12. (a)

REPAIR AGENCY DATEName Number

FIGURE 10-17. Sample weight and balance report to determine empty weight center of gravity.

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Page 10-22 Par 10-22

EQUIPMENT LIST*Required or Optional Item Numbers as Shown in Aircraft Specification

1 2 101 102 103 104 105106 201 202 203 301 302(a) 303

401(a) 402 ---- ---- ---- ---- ----Special Equipment

Item Make Model Weight Arm3 Flares 1-1/2 Min. XYZ 03 25# 105”

Enter above those items included in the empty weight.

WEIGHT AND BALANCE EXTREME CONDITIONSApproved fwd limit 8.5” Approved max. weight 2100# Approved aft limit 21.9”

Item FORWARD CHECK REARWARD CHECK Weight X Arm = Moment Weight X Arm = Moment

Airo. Empty + 1169(9 or 12a)

+ 10.6(11 or 12c)

+ 12391 + 1169(9 or 12a)

+ 10.6(11 or 12c)

+ 12391

Oil + 17 - 49 - 833 + 17 - 49 - 833Pilot + 170 + 16 + 2720 + 170 + 16 + 2720Fuel + 83 + 22 + 1826 + 240 + 22 + 5280

Passenger (s) + 340 + 48 + 16320Baggage + 100 + 75.5 + 7550TOTAL + 1439 = TW x + 16104 = TM + 2036 = TW x +43428=TM

TM = 16104 = +11.2” = TM = 43428 = +21.3” =TW 1439 TW 2036 Most Forward C.G. location Most Rearward C.G. location

LOADING SCHEDULEGallonsof Fuel

Number ofPassengers

Pounds ofBaggage

40 2(R) 100

The above includes pilot and capacity oil.

EQUIPMENT CHANGEComputing New C.G.

Item, Make, and Model* Weight X Arm MomentAirc. Empty + 1169

(9 or 12a)+ 10.6(11 or 12c)

+ 12391

204 added + 6 - 1 - 6302(b) added + 29 + 13 + 377302(a) removed - 24 + 29 + 696303 removed - 1 + 4 - 4NET TOTALS - 1179 = NW x + 13454 = NM

NM = 13454= +11.4” = New C.G.NW 1179

*ITEM NUMBERS WHEN LISTED IN PERTINENT AIRCRAFT SPECIFICATION MAY BE USED IN LIEU OF “ITEM, MAKE, AND MODEL”.PREPARED BY________________________________ DATE________________________

FIGURE 10-18. Sample weight and balance report including an equipment change for aircraft fully loaded.

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Par 10-22 Page 10-23

FIGURE 10-19. Permanent ballast computation formula.

10-23. LOADING SCHEDULE. Theloading schedule should be kept with the air-craft and form a part of the aircraft flight man-ual. It includes instructions on the proper loaddistribution such as filling of fuel and oiltanks, passenger seating, restrictions of pas-senger movement, and distribution of cargo.

a. Other means of determining safeloading conditions such as the use of agraphical index and load adjuster are

acceptable and may be used in lieu of the in-formation in paragraph 10-18.

b. Compute a separate loading condi-tion when the aircraft is to be loaded in otherthan the specified conditions shown in theloading schedule.

10-24. 10-34. [RESERVED.]