01 - pa-44-180 systems

PA-44-180 Systems

Table of Contents

Primary Flight Controls & Trim.....................................................................................................................1

Landing Gear............................................................................................................................................... 2

Brake System.............................................................................................................................................. 5

Powerplant................................................................................................................................................... 6

Propellers including controls and indicators.................................................................................................8

Fuel, oil and hydraulic systems....................................................................................................................9

Environmental System............................................................................................................................... 10

Deicing and anti-icing systems..................................................................................................................11

Avionics..................................................................................................................................................... 12

Systems unique to the airplane.................................................................................................................13

Pitot/Static/Vacuum Systems.....................................................................................................................14

Wing Flaps................................................................................................................................................. 21

Electrical System....................................................................................................................................... 22

Piper PA-44-180 SystemsMEI Lesson #1

Primary Flight Controls & Trim

References: Piper PA-44-180 POH 7-14 to 7-15

Ailerons

The PA-44-180, is fitted with two differential frise ailerons. The differential action combined with the extra drag produced by the frise aileron helps to counteract adverse yaw.

Frise Aileron

Rudder

The vertical tail is fitted with a rudder which incorporates a combination rudder trim and anti-servo tab. The rudder trim control is located on the control console between the front seats.

Stabilator

The horizontal tail surface (stabilator) is one of the all movable slab type with an anti-servo tab mounted on the trailing edge. This tab, actuated by a control mounted on the console between the front seats, also acts as a longitudinal trim tab.

Flaps

The flaps are manually operated and spring loaded to return to the retracted (up) position. A four position flap control handle located on the console between the front seats adjusts the flaps for reduced landing speeds and glide path control.

To extend the flaps, pull the handle up to the desired setting – 10, 25 or 40 degrees. To retract, depress the button on the end of the handle and lower the control.

An over-center lock incorporated in the actuating linkage holds the right flap when it is in the retracted (up) position so that it may be used as a step.

Trim

Trim surfaces are combined with the anti-servo tabs on both the rudder and stabilator primary control surfaces. Although trim is not meant for primary control of the airplane, it can be used effectively to make flying the airplane much easier. Both trim control wheels are located on the center console between the front seats.

Piper PA-44-180 SystemsMEI Lesson#1 Page 1

Landing Gear

References: Piper PA-44-180 POH 7-7 to 7-14

GeneralHydraulically Operated

Fully Retractable

Tricycle Landing Gear

AirspeedsVLO – 109 KIAS – On takeoff, the gear should be retracted before 109 KIAS.

VLE – 140 KIAS – The landing gear may be lowered at any airspeed up to 140 KIAS

Ground OperationsSteering

• Nose wheel steerable through a 30° arc either side of center by use of a combination of full rudder pedal travel and brakes

• A bungee assemble reduces ground steering effort and dampens shocks and bumps during taxiing

• When retracted, the nose wheel centers as it enters the wheel well and the steering linkage disengages to reduce pedal loads in flight

Tires

• Mains – 6.00 x 6, 8 ply tires (55 psi – POH 8-15)

• Nose – 5.00 x 5, 6 ply tire (50 psi – POH 8-15)

Struts

• Air-oil assemblies

• Main – 2.60 inches showing (POH 8-8)

• Nose – 2.70 inches showing (POH 8-8)

Normal OperationHydraulic Pump

• Electrically powered reversible pump

• Located aft of the baggage area. The fluid reservoir is also located here and should be filled with the proper fluid.

• Controlled by two-position switch with a wheel shaped knob located on the instrument panel

• Hydraulic pressure extends and retracts the gear. Operation takes approx 6-7 seconds.


Gear Up Operation

• Gear selector in UP position

• Hydraulic pressure holds the gear up (1800 psi)

• Pressure gauge will turn on pump when pressure drops 200 – 400 psi

• A convex mirror on the left engine nacelle allows the pilot to visually confirm the condition of the nose gear.

Gear Down Operation

• Gear selector in DOWN position

• Spring assists gear down and locked

• Spring keeps locking hook engaged

Annunciator Lights and Limit Switches

• WARNING GEAR UNSAFE – If the gear is in neither the full up nor the full down position

• GREEN LIGHTS – Three green lights indicate that the gear are down and locked.

• Lights are automatically dimmed when the navigation lights are on. If the green lights are not visible after selecting them in the down position, check the position of the nav light switch.

• Lights are controlled by limit switches located on the landing gear.

Nose Wheel

Up Lock (turns transit light off)

Down Lock (turns green light on)

Left Main



Stall Warning Disconnect(disables when on the ground)

Squat Pump Cutoff(no gear up on the ground)

Right Main



Heater Fan(disables heater fan when the airplane becomes airborne)

Emergency OperationGear Not Indicating Down and Locked

• Nav lights are on – check position of nav lights

• Gear not down and locked – recycle gear

• A bulb is burned out – try swapping bulbs

• There is a malfunction in the indicating system – request a flyby for inspection


Emergency Gear Extension

• In the event of hydraulic failure, the gear will automatically extend (held up by pressure)

• To manually relieve pressure and extend the gear, follow this procedure:

Ref: PA-44-180 POH 3-35

Slow to 100 KIASPlace the landing gear selector switch in the GEAR DOWN positionPull the emergency gear extension knob and check for three green lights

If the emergency gear knob has been pulled out in the event of a malfunction, leave it in the out position until a mechanic can inspect the system.

Other Warning Switches

• Micro switches in the throttle quadrant which activate the gear warning horn:

• Throttle reduced below 14” of manifold pressure on either engine and the gear is not in the DOWN and LOCKED position

• When the gear selector switch is in the UP position on the ground and MASTER switch is ON

• Flaps extended to the 25-40 degrees position and the gear is UP.

• A warning horn MUTE switch is located directly above the pilot’s attitude indicator.

• Will only mute a warning caused by the lowering of a throttle lever


Brake System

References: Piper PA-44-180 POH 7-14 & 8-8

Construction and Operation

• Two single disc, double puck, Cleveland brakes assemblies, one on each main gear

• FSI Seminoles equipped with heavy duty brakes (reduces ground roll)

• Actuated by toe brake pedals mounted on the pilot’s and co-pilot’s rudder pedals

• Total of four separate brake cylinders

• Allows differential braking to assist turning

Parking Brake

• Engaged: By depressing the toe brake pedals and pulling OUT parking brake handle

• Disengaged: By depressing the toe brake pedals and pushing IN parking brake handle

• Engaging the parking brake moves the parking brake valve to retain the hydraulic pressure in the brake lines.

Maintenance

• Fluid reservoir located in the top rear of the nose compartment

• Independent of the landing gear hydraulic system

• Filled with MIL-H-5506 (Petroleum Base) hydraulic brake fluid


Powerplant

References: Piper PA-44-180 POH 7-2, 1-3, 2-3,

EnginesThe Seminole is power by two Lycoming four-cylinder, direct drive, horizontally opposed, air cooled engines, each rated at 180 horsepower @ 2700 RPM at sea level.

Left Engine: O-360-A1H6

Right Engine: LO-360-A1H6

Engine mounts are constructed of steel tubing, and dynafocal engine mounts are provided to reduce vibration.

Counter rotating engines (and propellers) eliminates asymmetric thrust during takeoff.

• Left engine rotates clockwise, Right engine counter-clockwise when view from the cockpit

Carburetor is of the horizontal draft, float type

Engine Cooling and LubricationCooling air is regulated by adjusting the cowl flaps via a lever in the cockpit below the control quadrant. They have three positions, full open, full closed, and intermediate. To operate the cowl flaps, depress the lock and move the lever toward the desired setting. (Up – closed, down – open)

The oil, which also aids in engine cooling as well as lubrication, is cooled by an oil cooler with a low temperature bypass valve.

Oil is pumped through the engine by a gear type oil pump

Oil filtered by engine mounted oil filter

A winterization plate can be added to the oil cooler to reduce its effectiveness in cold climates

Refer to the POH/Maintenance Dept for proper grade of oil to use. Capacity is 8 quarts, but FSI suggests 6 quarts for normal operations involving maneuvers. Minimum safe quantity is 2 quarts.

Oil level can be checked by a dipstick accessible through a small door in the upper cowl of the engine nacelles.

Max cylinder head temp 500° F

Max oil temp 245° F

Oil pressure range 15-115 psi

Induction AirThe pilot has the option of two induction air sources which he/she controls by a carburetor heat control located below the quadrant control area.

Induction air box

• Manually operated two-way valve

• Selects between normal filtered air and unfiltered heated air that passes through a shroud around the exhaust pipe bypassing the air filter. (Up is off, down is on)

• The heated air can aid in the removal of carburetor ice or serve as an alternate air source should the induction air source become blocked (ice, snow, bird, etc.)

• Since the heated air is unfiltered, its use during ground operations should be limited to the run-up check because of the possibility of dust and other contaminants entering the engine.


ControlsEngine controls consist of:

• Two throttle levers – black (to adjust manifold pressure)

• Two propeller controls – blue (to adjust the propeller speed from high RPM to feather)

• Two mixture controls – red (to adjust the air to fuel ratio)

• The throttle levers incorporate a gear up warning horn switch which is activated during the last portion of travel of the throttle levers to the lower power position.

A friction lock located on the right side of the quadrant can be used to adjust the stiffness of the levers


Propellers including controls and indicators

References: Piper PA-44-180 POH

GeneralCounter-rotation of the propellers provides balanced thrust during takeoff and climb and eliminates the critical engine factor in single-engine flight.

Two blade, constant speed, controllable pitch and feathering Hartzell propellers are installed as standard equipment. The propellers mount directly to the engine crankshafts.

Pitch controlled by oil and nitrogen pressure.

• Oil pressure sends a propeller toward the high RPM (low pitch) or un-feather position

• Nitrogen pressure and a large spring sends a propeller toward the low RPM (high pitch) or feather position and also prevents propeller over-speeding.

Governors, one for each engine, supply engine oil at various pressures through the propeller shafts to maintain constant RPM settings.

• Controls engine speed by varying the pitch of the propeller to match load torque to engine torque in response to changing flight conditions

Each propeller is controlled by the propeller control levers located in the center of the power control quadrant (blue levers).

Feathering is accomplished by moving the control fully aft through the low RPM detent into the FEATHER position.

• Takes about 6-7 seconds.

• To un-feather, move the propeller control forward. This releases oil accumulated under pressure (accumulator) and moves the propeller out of the FEATHER position.

• In the event of an engine failure, the loss of oil pressure sends the propeller toward the FEATHER position.

Propeller GovernorsThe governor varies oil pressure to the propeller hub which in turn varies the RPM of the engine by varying the pitch of the propeller blades.

Main Components: The propeller control lever is connected to a cable which adjusts the tension of the speeder spring. The speeder spring tension determines the amount of rotation required to keep the flyweights in an on-speed condition. When the engine RPM reduces or increases the flyweights either move in or out which in turn moves the pilot valve down or up. The pilot valve then allows oil pressure to either flow to the hub from a high pressure oil pump or return to the crankcase until an on-speed condition exists.

Under-Speed

e.g., Going into a climb; or Tightening the speeder spring to

move to a higher RPM, e.g. final check.

Flyweights move in Pilot valve moves down Oil pressure moves to the hub,

reducing the prop pitch and increasing RPM until RPM reaches selected setting. (On-Speed)

On-Speed

i.e. Stabilized flight Flyweights level Pilot valve not up or down and

not increasing or decreasing oil pressure in the hub.

Maintaining constant RPM

Over-Speed

e.g. Going into a descent; or Loosening the speeder spring to

move to a lower RPM, e.g. setting climb or cruise power.

Flyweights move out. Pilot valve moves up Oil pressure returns from the

hub, increasing the prop pitch and reducing the RPM until RPM reaches selected setting. (On-Speed)


Fuel, oil and hydraulic systems


Environmental System


Deicing and anti-icing systems


Avionics


Systems unique to the airplane


Pitot/Static/Vacuum Systems

GYROSCOPIC FLIGHT INSTRUMENTS

Several flight instruments utilize the properties of a gyroscope for their operation. The most common instruments containing gyroscopes are the turn coordinator, heading indicator, and the attitude indicator. To understand how these instruments operate requires a knowledge of the instrument power systems, gyroscopic principles, and the operating principles of each instrument.

Sources of Power for Gyroscopic Operation

In some airplanes, all the gyros are vacuum, pressure, or electrically operated ; in others, vacuum, or pressure systems provide the power for the heading and attitude indicators, while the electrical system provides the power for the turn coordinator.

Vacuum or Pressure System

The vacuum or pressure system spins the gyro by drawing a stream of air against the rotor vanes to spin the rotor at high speeds essentially the same as a water wheel or turbine operates. The amount of vacuum or pressure required for instrument operation varies with manufacture and is usually between 4.5 to 5.5 in. Hg.

Engine-Driven Vacuum Pump

One source of vacuum for the gyros installed in light aircraft is the vane-type engine-driven pump which is mounted on the accessory case of the engine. Pump capacity varies in different aircraft, depending on the number of gyros to be operated.


A typical vacuum system consists of an engine-driven vacuum pump, regulator, air filter, gauge, tubing, and manifolds necessary to complete the connections. The gauge is mounted in the airplane instrument panel and indicates the amount of pressure in the system. [Figure 3-5]

The air filter prevents foreign matter from entering the vacuum or pressure system. Airflow is reduced as the master filter becomes dirty; this results in a lower reading on the vacuum or pressure gauge.

Gyroscopic Principles

Any spinning object exhibits gyroscopic properties; however, a wheel designed and mounted to utilize these properties is called a gyroscope. Two important design characteristics of an instrument gyro are great weight or high density for size and rotation at high speeds with low friction bearings. The mountings of the gyro wheels are called "gimbals" which may be circular rings, rectangular frames, or a part of the instrument case itself.

There are two general types of mountings; the type used depends upon which property of the gyro is utilized. A freely or universally mounted gyroscope is free to rotate in any direction about its center of gravity. Such a wheel is said to have three planes of freedom. The wheel or rotor is free to rotate in any plane in relation to the base and is so balanced that with the gyro wheel at rest, it will remain in the position in which it is placed. Restricted or semirigidly mounted gyroscopes are those mounted so that one of the planes of freedom is held fixed in relation to the base.

There are two fundamental properties of gyroscopic action; rigidity in space, and precession.

Rigidity in space can best be explained by applying Newton's First Law of Motion which states, "a body at rest will remain at rest; or if in motion in a straight line, it will continue in a straight line unless acted upon by an outside force." An example of this law is the rotor of a universally mounted gyro. When the wheel is spinning, it exhibits the ability to remain in its original plane of rotation regardless of how the base is moved. However, since it is impossible to design bearings without some friction present, there will be some deflective force upon the wheel.

Figure 3-5. -- Typical pump-driven vacuum system.


Figure 3-6. -- Precession of a gyroscope resulting from an applied deflective force.

The flight instruments using the gyroscopic property of rigidity for their operation are the attitude indicator and the heading indicator; therefore, their rotors must be freely or universally mounted.

The second property of a gyroscope “precession” is the resultant action or deflection of a spinning wheel when a deflective force is applied to its rim. When a deflective force is applied to the rim of a rotating wheel, the resultant force is 90° ahead in the direction of rotation and in the direction of the applied force. The rate at which the wheel precesses is inversely proportional to the speed of the rotor and proportional to the deflective force. The force with which the wheel precesses is the same as the deflective force applied (minus the friction in the bearings). If too great a deflective force is applied for the amount of rigidity in the wheel, the wheel precesses and topples over at the same time. [Figure 3-6]

Turn Coordinator

The turn coordinator shows the yaw and roll of the aircraft around the vertical and longitudinal axes.

When rolling in or rolling out of a turn, the miniature airplane banks in the direction of the turn.

The miniature airplane does not indicate the angle of bank, but indicates the rate of turn. When aligned with the turn index, it represents a standard rate of turn of 3° per second. [Figure 3-7]


Figure 3-7. -- Turn coordinator.

The inclinometer of the turn coordinator indicates the coordination of aileron and rudder. The ball indicates whether the airplane is in coordinated flight or is in a slip or skid. [Figure 3-8]

The Heading Indicator

The heading indicator (or directional gyro) is fundamentally a mechanical instrument designed to facilitate the use of the magnetic compass. Errors in the magnetic compass are numerous, making straight flight and precision turns to headings difficult to accomplish, particularly in turbulent air. A heading indicator, however, is not affected by the forces that make the magnetic compass difficult to interpret. [Figure 3-9]

Figure 3-8. -- Turn coordinator indications.


Figure 3-9. -- Heading indicator.

The operation of the heading indicator depends upon the principle of rigidity in space. The rotor turns in a vertical plane, and fixed to the rotor is a compass card. Since the rotor remains rigid in space, the points on the card hold the same position in space relative to the vertical plane. As the instrument case and the airplane revolve around the vertical axis, the card provides clear and accurate heading information.

Because of precession, caused chiefly by friction, the heading indicator will creep or drift from a heading to which it is set. Among other factors, the amount of drift depends largely upon the condition of the instrument. If the bearings are worn, dirty, or improperly lubricated, the drift may be excessive.

Bear in mind that the heading indicator is not direction-seeking, as is the magnetic compass. It is important to check the indications frequently and reset the heading indicator to align it with the magnetic compass when required. Adjusting the heading indicator to the magnetic compass heading should be done only when the airplane is in wings-level unaccelerated flight; otherwise erroneous magnetic compass readings may be obtained.

The bank and pitch limits of the heading indicator vary with the particular design and make of instrument. On some heading indicators found in light airplanes, the limits are approximately 55° of pitch and 55° of bank. When either of these attitude limits is exceeded, the instrument " tumbles" or "spills" and no longer gives the correct indication until reset. After spilling, it may be reset with the caging knob. Many of the modern instruments used are designed in such a manner that they will not tumble.


The Attitude Indicator

The attitude indicator, with its miniature aircraft and horizon bar, displays a picture of the attitude of the airplane. The relationship of the miniature aircraft to the horizon bar is the same as the relationship of the real aircraft to the actual horizon. The instrument gives an instantaneous indication of even the smallest changes in attitude. [Figure 3-10]

Figure 3-10. -- Attitude indicator.

Figure 3-11. -- Various indications on the attitude indicator.

The gyro in the attitude indicator is mounted on a horizontal plane and depends upon rigidity in space for its operation. The horizon bar represents the true horizon. This bar is fixed to the gyro and remains in a horizontal plane as the airplane is pitched or banked about its lateral or longitudinal axis, indicating the attitude of the airplane relative to the true horizon.


An adjustment knob is provided with which the pilot may move the miniature airplane up or down to align the miniature airplane with the horizon bar to suit the pilot's line of vision. Normally, the miniature airplane is adjusted so that the wings overlap the horizon bar when the airplane is in straight-and-level cruising flight.

The pitch and bank limits depend upon the make and model of the instrument. Limits in the banking plane are usually from 100° to 110°, and the pitch limits are usually from 60° to 70°. If either limit is exceeded, the instrument will tumble or spill and will give incorrect indications until restabilized. A number of modern attitude indicators will not tumble.

Every pilot should be able to interpret the banking scale. Most banking scale indicators on the top of the instrument move in the same direction from that in which the airplane is actually banked. Some other models move in the opposite direction from that in which the airplane is actually banked. This may confuse the pilot if the indicator is used to determine the direction of bank. This scale should be used only to control the degree of desired bank. The relationship of the miniature airplane to the horizon bar should be used for an indication of the direction of bank. [Figure 3-11]

The attitude indicator is reliable and the most realistic flight instrument on the instrument panel. Its indications are very close approximations of the actual attitude of the airplane.


Wing Flaps

Wing flaps, installed on the wings of most modern airplanes, have two important functions. First, they permit a slower landing speed and, therefore, decrease the required landing distance. Second, because they permit a comparatively steep angle of descent without an increase in speed, it is possible, while making maximum utilization of the available landing area, to safely clear obstacles when making a landing approach to a small field. They may also be used to shorten the takeoff distance and provide a steeper climb path.

Most wing flaps are hinged near the trailing edges of the wings, inboard of the ailerons (Fig. 2-7). They are controllable by the pilot either manually, electrically, or hydraulically. When they are in the up (retracted) position, they fit flush with the wings and serve as part of the wing's trailing edge. When in the down (extended) position, the flaps pivot downward from the hinge points to various angles ranging up to 40° - 50° from the wing. This in effect increases the wing camber (curvature) and angle of attack, thereby providing greater lift and more drag so that the airplane can descend or climb at a steeper angle or a slower airspeed.


Electrical System

GeneralNegative ground, dual-fed, split-bus, system capable of supplying sufficient current for complete night IFR equipment.

Alternators

• Two belt driven 14 volt, 70 ampere alternators

• Provides output even at low engine rpms

Voltage Regulators

• Maintain effective load sharing

• Regulates system bus voltage to 14 volts

• Overvoltage relay takes an alternator off line if voltage exceeds 17 volts

• In that case, the ALTernator light will illuminate

• Located in the nose section

Battery

• 35 ampere-hour, 12 volt battery

• Used for starting and backup power

• Charged by alternators during flight

• Located in nose section

Circuit Breakers

• The electrical system and equipment are protected by circuit breakers loacated on a circuit breaker panel on the lower right side of the instrument panel.

• May be pulled manually

Power Distribution

• Battery Bus

• Provides continuous power to the clock, engine hourmeter, the flight time hourmeter, and the heater hourmeter.

• Works even when master switch is off

• When the battery master switch is turned ON , the battery solenoid contactor closes, enabling current to flow from the battery to both the starter contactors and the tie bus.

• Protected by 60 amp BATTERY c.b.

• All other busses and alternators are “tied” to this bus

• Each alternator system has an independent ON-OFF rocker switch and a solid state voltage regulator that automatically regulates alternator field current.

• When in the ON position, the positive output of each alternator is fed through individual shunts to the tie bus.

• Overcurrent protection is provided by the 70 amp tie bus L ALT and R ALT circuit breakers

• A main bus, a non-essential bus, and two avionics buses, with associated circuit breakers, are located at the circuit breaker panel.


• The two avionics busses are interconnected through the avionics bus 25 amp AVI BUS TIE circuit breaker.

• Current is fed from the tie bus to the main bus by two conductors.

• Inline diodes prevent revers current flow to the tie bus

• Two tie bus 60 amp MAIN BUS circuit breakers protect the main bus from an overload

• Current from the tie bus is fed to each avionics bus through independent solenoid contactors.

• When radio master is selected ON, both solenoids close

• Both busses are protected by 40 amp AVI BUS #1, and AVI BUS #2 circuit breakers

• Should the need arise, either bus can be isolated by pulling the AVI BUS TIE breaker

• Non-essential bus is also fed from the tie bus.

• Overload protection is provided by the tie bus 40 amp NON ESS circuit breaker

System Monitors

• Dual ammeters

• Two annunciator lights, located at upper right of pilot’s panel

• Lo-Bus light will illuminate if bus voltage drops to batter voltage (12.5 Vdc)

External Power Receptacle

• Should the airplane’s battery be depleted, a receptacle located on the lower right side of the nose section permits using an external battery for engine start.


01 - pa-44-180 systems

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