ata 51-57 structure
DESCRIPTION
ATA 51TRANSCRIPT
Training Manual ATA 51-57 – Structures
Boeing 737-300/400/500 –CFM56-3 ATA 104 - Level 3 B1/B2
FOR TRAINING PURPOSES ONLY 1
ATA 51 - 57 STRUCTURES
Revision 1/ October 2011
Training Manual ATA 51-57 – Structures
Boeing 737-300/400/500 –CFM56-3 ATA 104 - Level 3 B1/B2
FOR TRAINING PURPOSES ONLY 2
For training purposes only.
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Training Manual ATA 51-57 – Structures
Boeing 737-300/400/500 –CFM56-3 ATA 104 - Level 3 B1/B2
FOR TRAINING PURPOSES ONLY
TABLE OF CONTENTS
ATA 52-57……………………………………………………………………………………………………………………..9
DIMENSION AND AREAS…………………………………………………………………………………………………..10
INTRODUCTION……………………………………………………………………………………………………………..10
MAINTENANCE PRACTICES……………………………………………………………………………………………..12
PRINCIPAL DIMENSIONS AND AREAS…………………………………………………………………………………14
LIFTING AND SHORING / JACKING……………………………………………………………………………………..18
TOWING AND TAXING…………………………………………………………………………………………………….20
POWERPLANT AND INLET DANGER AREAS…………………………………………………………………...…….22
WARNING PLACARDS…………………………………………………………………………………………………….25
ATA 53 FUSELAGE………………………………………………………………………………………………………..27
53-00 GENERAL……………………………………………………………………………………………………………27
FUSELAGE GENERAL DESCRIPTION………………………………………………………………………………….29
FUSELAGE GENERAL DESCRIPTION………………………………………………………………………………….30
FUSELAGE GENERAL DESCRIPTION (CONT.)……………………………………………………………………….32
ATA 57 WINGS……………………………………………………………………………………………………………..34
57-00 GENERAL……………………………………………………………………………………………………………34
WINGS GENERAL DESCRIPTION……………………………………………………………………………………….34
WINGS GENERAL DESCRIPTION (CONT)……………………………………………………………………………..36
ATA 54 NACELLES / PYLONS…………………………………………………………………………………………...40
54-00 GENERAL…………………………………………………………………………………………………………….40
STRUT………………………………………………………………………………………………………………………..40
NACELLE…………………………………………………………………………………………………………………….43
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Training Manual ATA 51-57 – Structures
Boeing 737-300/400/500 –CFM56-3 ATA 104 - Level 3 B1/B2
FOR TRAINING PURPOSES ONLY
ATA 55 STABILIZER……………………………………………………………………………………………………….46
55-10 HORIZONTAL STABILIZER……………………………………………………………………………………….46
GENERAL DESCRIPTION………………………………………………………………………………………………...46
GENERAL DESCRIPTION (CONT)………………………………………………………………………………………47
55-30 VERTICAL STABILIZER…………………………………………………………………………...………………52
GENERAL DESCRIPTION…………………………………………………………………………………………………52
ATA 52 DOORS…………………………………………………………………………………………………………….56
52-00 GENERAL……………………………………………………………………………………………………………56
INTRODUCTION……………………………………………………………………………………………………………56
52-10 PASSENGER / CREW……………………………………………………………………………………………..59
ENTRY DOOR………………………………………………………………………………………...……………………59
ENTRY DOOR MECHANISM……………………………………………………………………………………………..62
FORWARD ENTRY DOOR OPERATION……………………………………………………………………………….67
CAM PLATE OPERATION………………………………………………………………………………………………...69
UPPER HINGE / GUIDE ARM GEOMETRY…………………………………………………………………………….71
52-40 SERVICE……………………………………………………………………………………………………………..73
GALLEY SERVICE DOOR…………………………………………………………………………………………………73
LOWER NOSE COMPARTMENT ACCESS DOOR…………………………………………………………………….75
ELECTRONIC EQUIPMENT COMPARTMENT ACCESS DOOR…………………………………………………….77
ELECTRONIC EQUIPMENT COMPARTMENT ACCESS DOOR (CONT)…………………………………………..80
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Training Manual ATA 51-57 – Structures
Boeing 737-300/400/500 –CFM56-3 ATA 104 - Level 3 B1/B2
FOR TRAINING PURPOSES ONLY
52-20 EMERGENCY EXIT………………………………………………………………………………………….82
EMERGENCY EXIT HATCH……………………………………………………………………………………….82
EMERGENCY HATCH DETAILS………………………………………………………………………………….84
EMERGENCY EXIT HATCH OPERATION………………………………………………………………………87
52-30 CARGO………………………………………………………………………………………………………..89
CARGO COMPARTMENT DOORS……………………………………………………………………………….89
CARGO DOOR OPERATION……………………………………………………………………………………...94
FLIGHT COMPARTMENT DOOR EMERGENCY EXIT FEATURE……………………………...……………97
FLIGHT COMPARTMENT DOOR LOCK…………………………………………………………………………99
DOOR LOCK OPERATION………………………………………………………………………………..……..101
FLIGHT COMPARTMENT DOOR EMERGENCY EXIT FEATURE………………………………………….103
52-70 DOOR WARNING………………………………………………………………………………………..…106
DOOR UNLOCK INDICATORS………………………………………………………………………………...…106
ATA 56 WINDOWS…………………………………………………………………………………………………109
56-00 GENERAL……………………………………………………………………………………………………109
INTRODUCTION……………………………………………………………………………………………………109
56-10 FLIGHT COMPARTMENT………………………………………………………………………………….111
FLIGHT COMPARTMENT WINDOWS……………………………………………………………………………111
WINDOW NO. 1……………………………………………………………………………………………………...114
WINDOW NO. 3 (CONFIG 1)………………………………………………………………………………………116
WINDOWS NO. 4 & 5……………………………………………………………………………………………….118
WINDOWS NO. 2……………………………………………………………………………………………………120
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Training Manual ATA 51-57 – Structures
Boeing 737-300/400/500 –CFM56-3 ATA 104 - Level 3 B1/B2
FOR TRAINING PURPOSES ONLY
56-20 PASSENGER COMPARTMENT………………………………………………………………………………122
FUNCTIONAL DESCRIPTION………………………………………………………………………………………...122
SEAL LEAK DETECTION………………………………………………………………………………...……………124
EDGE DAMAGE…………………………………………………………………………………………………………126
WINDOW CONCAVITY…………………………………………………………………………………………………128
56-40 INSPECTION AND OBSERVATION…………………………………………………………………………..130
INSPECTION WINDOW………………………………………………………………………………………………...130
ATA 25 EQUIPMENT / FURNISHING…………………………………………………………………………………133
25-00 GENERAL…………………………………………………………………………………………………………133
INTRODUCTION…………………………………………………………………………………………………………133
25-10 FLIGHT COMPARTMENT………………………………………………………………………………………135
FLIGHT COMPARTMENT EQUIPMENT LOCATION……………………………………………………………….135
PILOTS’ SEAT……………………………………………………………………………………………………………137
PILOTS’ SEAT REMOVAL & INSTALLATION………………………………………………………………………..139
OBSERVER’S SEAT…………………………………………………………………………………………………….141
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Training Manual ATA 51-57 – Structures
Boeing 737-300/400/500 –CFM56-3 ATA 104 - Level 3 B1/B2
FOR TRAINING PURPOSES ONLY
25-20 PASSENGER COMPARTMENT……………………………………………………………………………………….143
COMPONENT FUNCTIONAL DESCRIPTION……………………………………………………………………………….143
PASSENGER COMPARTMENT SEATS……………………………………………………………………………………..145
PASSENGER COMPARTMENT SEATS (CONT)……………………………………………………………………………147
SIDEWALL LININGS…………………………………………………………………………………………………………….149
WINDOW REVEAL ASSEMBLY……………………………………………………………………………………………….151
SIDEWALL RISER PANELS AND AIR GRILLES……………………………………………………………………………153
SCULPTURED CEILING PANELS…………………………………………………………………………………………….155
CEILING PANEL HINGE ASSEMBLY…………………………………………………………………………………………155
PASSENGER SERVICE UNITS………………………………………………………………………………………………..157
OVERHEAD STOWAGE COMPARTMENT…………………………………………………………………………………..160
OVERHEAD STOWAGE COMPARTMENTS (CONT)……………………………………………………………………….162
25-30 BUFFET / GALLEY………………………………………………………………………………………………………164
GALLEY LOCATIONS AND IDENTIFICATION……………………………………………………………………………….164
GALLEY INSTALLATION………………………………………………………………………………………………………..166
GALLEY SERVICE POWER (CONFIG. 1)…………………………………………………………………………………….168
GALLEY SERVICE POWER (CONFIG. 2)…………………………………………………………………………………….170
25-40 LAVATORIES……………………………………………………………………………………………………………..172
LAVATORIY EQUIPMENT………………………………………………………………………………………………………172
25-50 CARGO COMPARTMENTS……………………………………………………………………………………………..174
CARGO COMPARTMENTS……………………………………………………………………………………………………..174
CARGO NET………………………………………………………………………………………………………………………176
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Training Manual ATA 51-57 – Structures
Boeing 737-300/400/500 –CFM56-3 ATA 104 - Level 3 B1/B2
FOR TRAINING PURPOSES ONLY
25-60 EMERGENCY……………………………………………………………………………………………………………..178
EMERGENCY EQUIPMENT…………………………………………………………………………………………………….178
ESCAPE STRAP………………………………………………………………………………………………………………….180
DOOR MOUNTED ESCAPE SLIDES…………………………………………………………………………………………..182
ESCAPE SLIDE MAINTENANCE PRACTICES……………………………………………………………………………….184
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Training Manual ATA 51-57 – Structures
Boeing 737-300/400/500 –CFM56-3 ATA 104 - Level 3 B1/B2
FOR TRAINING PURPOSES ONLY
ATA 52-57
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Training Manual ATA 51-57 – Structures
Boeing 737-300/400/500 –CFM56-3 ATA 104 - Level 3 B1/B2
FOR TRAINING PURPOSES ONLY
DIMENSION AND AREAS
THE AIRPLANE IS A METAL LOW-WING MONOPLANE WITH A FULL CANTILEVER WING AND
TAIL SURFACES, SEMI-MONOCOQUE FUSELAGE, AND FULLY RETRACTABLE TRICYCLE-
TYPE LANDING GEAR.
THE TWO POWERPLANTS ARE LOCATED ON THE LEFT AND RIGHT WING ON SHORT
STRUTS BELOW AND FORWARD OF THE WING.
THE BOEING 737-300 / -400 / -500 TWIN ENGINE AIRPLANE IS DESIGNED FOR SHORT TO
MEDIUM RANGE OPERATION.
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Training Manual ATA 51-57 – Structures
Boeing 737-300/400/500 –CFM56-3 ATA 104 - Level 3 B1/B2
FOR TRAINING PURPOSES ONLY
Figure 1
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Training Manual ATA 51-57 – Structures
Boeing 737-300/400/500 –CFM56-3 ATA 104 - Level 3 B1/B2
FOR TRAINING PURPOSES ONLY
MAINTENANCE PRACTICES
General
The airplane is divided into stations, waterlines, and buttock lines. They are measured in inches. They will help you
quickly identify the location of components, the center of gravity and the weight distribution. Standard Abbreviations
and Definitions:
FUSELAGE
BSTA, BS, or STA
Body (Fuselage) Station. A plane that is perpendicular to the fuselage centerline. It is measured from a point 130.00
inches forward of the nose.
BBL or BL
Body (Fuselage) Buttock Line. A vertical plane that is parallel to the vertical centerline plane, BBL 0.00. It is found by
its perpendicular distance from the fuselage centerline plane. (It is a measurement of width.)
BRP
Body (Fuselage) Reference Plane. A plane that is perpendicular to the BBL plane and goes through BWL 208.10, the
top of the main deck floor beams.
BWL or WL
Body (Fuselage) Waterline. A plane that is perpendicular to the BBL plane, parallel to the fuselage centerline. It is
measured from a parallel imaginary plane, BWL 0.00, 148.5 inches below the lowest fuselage surface.
LBL
Left Buttock Line
RBL
Right Buttock Line
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Training Manual ATA 51-57 – Structures
Boeing 737-300/400/500 –CFM56-3 ATA 104 - Level 3 B1/B2
FOR TRAINING PURPOSES ONLY
Figure 2
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Training Manual ATA 51-57 – Structures
Boeing 737-300/400/500 –CFM56-3 ATA 104 - Level 3 B1/B2
FOR TRAINING PURPOSES ONLY
PRINCIPAL DIMENSIONS AND AREAS General
Dimensions are included for the wing, ailerons, flaps, horizontal stabilizer surfaces, vertical stabilizer surfaces and
body. Areas are included for the wing and stabilizer surfaces.
Dimensions Overall Airplane
- Length -- 109 feet-7 inches (737-300)
- Length -- 119 feet-7 inches (737-400)
- Length -- 101 feet-9 inches (737-500)
- Width -- 94 feet-10 inches
-Height (vertical stabilizer tip, top of the fairing to the ground) – 36 feet-6 inches
Fuselage
Height of the body reference plane (top of the floor beam WL 208.10).
Above the ground at the main gear -- 102.10 inches.
Height (constant cross section)
- Above the body reference plane -- 98.4 inches
- Below the body reference plane -- 59.60 inches
- Height to the centerline of the windows above the body reference plane
-- 38 inches
- Length -- 1267 inches (737-300)
- Length -- 1387 inches (737-400)
- Length -- 1173 inches (737-500)
Areas
Wing (basic) -- 980.0 square feet
Horizontal Stabilizer Surfaces (total, with the area in the fuselage) – 545 square feet
Vertical Stabilizer Surfaces (total) -- 370 square feet
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Training Manual ATA 51-57 – Structures
Boeing 737-300/400/500 –CFM56-3 ATA 104 - Level 3 B1/B2
FOR TRAINING PURPOSES ONLY
Figure 3
B737-300
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Training Manual ATA 51-57 – Structures
Boeing 737-300/400/500 –CFM56-3 ATA 104 - Level 3 B1/B2
FOR TRAINING PURPOSES ONLY
Figure 4
B737-400
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Training Manual ATA 51-57 – Structures
Boeing 737-300/400/500 –CFM56-3 ATA 104 - Level 3 B1/B2
FOR TRAINING PURPOSES ONLY
Figure 5
B737-500
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Training Manual ATA 51-57 – Structures
Boeing 737-300/400/500 –CFM56-3 ATA 104 - Level 3 B1/B2
FOR TRAINING PURPOSES ONLY
LIFTING & SHORING
JACKING
JACKING POINTS
The airplane has three main jack points and four auxiliary jacking points. The main points are wing jacking points A and B
and aft body jacking point C. The four auxiliary points are forward body jacking point D and three landing gear points, E
(nose) and F (Main Landing Gear). The airplane may be jacked at any gross weight provided the maximum load of any
jacking point is not exceeded. If the airplane is supported entirely by the three main jacks and the stabilizing jack at point D,
the maximum jacking weight of the airplane must not be exceeded.
Maximum jacking weight for the basic
- 737-300 is 43,092 kg (95,000 pounds);
- the 737-400 is 49,896 kg (110,000 pounds)
- and the 737-500 is 40,824 kg (90,000 pounds).
Axle jacking points E and F provide the means for changing two flat tires on the same axle up to maximum gross taxi weight.
Landing gear jack points are integral 3/4 inch spherical radius pads under main and nose gear axles.
The jacking points on the wing and body include special provisions for the attachment of bolt-on type jack adapters provided
with 3/4 inch spherical radius pads. To minimize the vertical lift during the jacking operation, main and nose gear shock strut
restrainers which lock the oleos in a de-pressurized and compressed condition may be used if gear retraction is not the
reason for jacking.
CAUTION: DO NOT LIFT THE AIRPLANE ON JACKS IN WINDS MORE THAN 35 KNOTS. IF YOU DO NOT OBEY
THESE INSTRUCTIONS DAMAGE TO THE AIRPLANE CAN OCCUR.
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Training Manual ATA 51-57 – Structures
Boeing 737-300/400/500 –CFM56-3 ATA 104 - Level 3 B1/B2
FOR TRAINING PURPOSES ONLY
FIGURE 6
Jack Point Locations
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Training Manual ATA 51-57 – Structures
Boeing 737-300/400/500 –CFM56-3 ATA 104 - Level 3 B1/B2
FOR TRAINING PURPOSES ONLY
TOWING & TAXIING
TOWING
TOWING AND TAXIING CLEARANCES
The airplane is normally towed or pushed by a tow bar attached to the nose gear. Maximum normal towing turning limits are
indicated by red stripes on the nose gear doors.
Maximum tow bar movement 78 either side. Tip clearances require special care during the turn. Brakes should not be used
during turns except in emergencies. Airplane should be moving before turning the nose wheel. Airplane nose wheel should
be fore and aft prior to parking.
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Training Manual ATA 51-57 – Structures
Boeing 737-300/400/500 –CFM56-3 ATA 104 - Level 3 B1/B2
FOR TRAINING PURPOSES ONLY
FIGURE 7
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Training Manual ATA 51-57 – Structures
Boeing 737-300/400/500 –CFM56-3 ATA 104 - Level 3 B1/B2
FOR TRAINING PURPOSES ONLY
POWER PLANT AND INLET DANGER AREAS
The wing-mounted engines require that the ground personnel be aware of the danger areas. The engine inlet efficiently
directs air into the engine.
The characteristics of jet engine operation require extreme care to prevent injury to personnel and/or damage to equipment.
An operating engine consumes large quantities of air and is capable of sucking large objects into the inlet including
humans. The exhaust of an operating engine has a velocity capable of overturning work stands, carts and at high engine
power can easily pick up humans. Also the noise of the operating engine can be harmful to the human hearing system.
Numerous incidents have been reported including injury to personnel by jet engines. One incident has resulted in a fatality.
The powerplant danger areas are the air inlet and exhaust from the fan and core sections of the engine. All these sections
provide hazards due to high air velocity and generated noise.
Operation
A typical engine inlet hazard area extends fan shaped forward from the inlet and aft from the inlet lip to the forward end of
the cowl panels. When the engine is operating above idle thrust the hazard area extends further forward from the inlet and
further aft of the nose cowl inlet lip. Personnel working on the engine aft of the inlet should take special care to strictly avoid
this hazard area.
WARNING: DURING GROUND RUNNING OPERATION THE ENGINE IS CAPABLE OF DEVELOPING ENOUGH
SUCTION AT THE INLET TO PULL A PERSON UP TO OR INTO THE DUCT WITH POSSIBLE FATAL RESULTS.
THEREFORE, WHEN APPROACHING ANY JET ENGINE, PRECAUTIONS MUST BE TAKEN TO KEEP CLEAR OF ALL
INLET AIR STREAM. THE SUCTION NEAR THE INLET CAN ALSO PULL HATS, GLASSES, LOOSE CLOTHING AND
WIPERAGS FROM POCKETS INTO THE ENGINE. ANY LOOSE ARTICLES MUST BE MADE SECURE OR REMOVED
BEFORE WORKING AROUND THE ENGINE.
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Training Manual ATA 51-57 – Structures
Boeing 737-300/400/500 –CFM56-3 ATA 104 - Level 3 B1/B2
FOR TRAINING PURPOSES ONLY
FIGURE 8
Inlet and Exhaust Dangers Areas
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Training Manual ATA 51-57 – Structures
Boeing 737-300/400/500 –CFM56-3 ATA 104 - Level 3 B1/B2
FOR TRAINING PURPOSES ONLY
FIGURE 9
Inlet and Exhaust Dangers Areas
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Training Manual ATA 51-57 – Structures
Boeing 737-300/400/500 –CFM56-3 ATA 104 - Level 3 B1/B2
FOR TRAINING PURPOSES ONLY
WARNING PLACARDS
Warning
The danger areas associated with a running engine are identified by placards. The placards are located on each side of the
nacelle near the fan exhaust. The warning placard consists of a stripe, a silhouette of the engine indicating inlet and exhaust
danger areas, an international ―NO ENTRY TO PERSONNEL‖ sign and a warning text. The color of the placard is red.
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Training Manual ATA 51-57 – Structures
Boeing 737-300/400/500 –CFM56-3 ATA 104 - Level 3 B1/B2
FOR TRAINING PURPOSES ONLY
FIGURE 10
Warning Placards
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Training Manual ATA 51-57 – Structures
Boeing 737-300/400/500 –CFM56-3 ATA 104 - Level 3 B1/B2
FOR TRAINING PURPOSES ONLY
ATA 53 FUSELAGE
53-00 GENERAL
FUSELAGE GENERAL DESCRIPTION
Purpose
The fuselage is a structurally sound and aerodynamically contoured body which supports the wings, stabilizers and
landing gear. Most of it is pressurized for the coverage of payload.
System Description
A typical section through the fuselage consists of an upper and a lower oval which intersect approximately at the floor
level. At the intersection, the fuselage is reinforced by transverse floor beams. Above this floor structure, which extends
from the front pressure bulkhead at Body Station 178 to the rear pressure bulkhead at Body Station 1016, the upper
lobe of the fuselage encloses the cabin and is basically a continuous shell, with cutouts in the skin for doors and
windows. Below the floor the continuity of the lower lobe, which encloses the cargo compartments, is interrupted by
several major structural features: the nose landing gear wheel well, the cavity for the center wing box, and the main
landing gear wheel well. Aft of the rear pressure bulkhead, the floor is discontinued and this section of the fuselage, which
tapers towards its aft end, supports the vertical fin, the horizontal stabilizer, and contains a compartment for the APU.
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Training Manual ATA 51-57 – Structures
Boeing 737-300/400/500 –CFM56-3 ATA 104 - Level 3 B1/B2
FOR TRAINING PURPOSES ONLY
B737-300
Figure 11
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Training Manual ATA 51-57 – Structures
Boeing 737-300/400/500 –CFM56-3 ATA 104 - Level 3 B1/B2
FOR TRAINING PURPOSES ONLY
FUSELAGE GENERAL DESCRIPTION
General
Special design features maintain structural continuity between Body Stations 540 and 727 where the cavities for the center
wing box and the main landing gear interrupt the lower half of the basically tubular fuselage. A keel beam connects the
bottom of the fuselage frame at Station 540 with the bottom of the frame at Station 664 and passes below the center wing
box. The fuselage is divided into production or manufacturing sections, these being:
- Section 41 from STA 130 to STA 360
- Section 43 from STA 360 to STA 540
- Section 46 from STA 540 to STA 1016
-Section 48 from STA 1016 to STA 1217
The fuselage is manufactured in four body sections connected by production or manufacturing breaks to form a complete
integral structure. The forward three sections form the pressurized shell of the fuselage and enclose the crew, passenger,
and cargo accommodations. The main frame includes frames, bulkheads, formers, longerons, stringers, keel beam and
frames around openings. Each frame is a zee-section circumferential member, with increased web depth at floor level.
The frames are generally spaced at twenty-inch intervals along the fuselage aft of the flight deck.
The bulkhead at Body Station 178 is the forward end of the pressure cabin and is composed of four vertical beams and a
flat pressure web which the beams divide into small panels.
At Body Station 227.8 a frame, with a web extending across the lower part of it, forms the forward wall of the nose landing
gear wheel well. At Body Station 294.5 a frame, with a web extending across the lower part of it, forms the aft
wall of the nose landing gear wheel well.
At Body Station 360, a bulkhead extends across the fuselage from floor level and down to form the forward wall of the
forward cargo compartment.
At Body Station 500D, a bulkhead extends across the fuselage from floor level and down. This bulkhead serves as the aft
wall of the forward cargo compartment.
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Training Manual ATA 51-57 – Structures
Boeing 737-300/400/500 –CFM56-3 ATA 104 - Level 3 B1/B2
FOR TRAINING PURPOSES ONLY
-continued-
At Body Station 664, a bulkhead extends across the fuselage from floor level and down. This bulkhead serves as the aft spar
of the center wing box and the forward wall of the main landing gear wheel well.
At Body Station 727, a bulkhead extends across the fuselage from floor level and down. This bulkhead serves as the aft wall
of the main landing gear wheel well and the forward wall of the aft cargo compartment.
The pressure bulkhead at Body Station 1016 is a curved web extending aft like a dome in the vertical plane. The web is
reinforced with radii stringers all originating at the center of the web. The web forms the aft end of the pressurized
cabin. The vertical fin front spar attach fittings are at the top of the fuselage at Body Station 1016.
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Training Manual ATA 51-57 – Structures
Boeing 737-300/400/500 –CFM56-3 ATA 104 - Level 3 B1/B2
FOR TRAINING PURPOSES ONLY
B737-400
Figure 12
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Training Manual ATA 51-57 – Structures
Boeing 737-300/400/500 –CFM56-3 ATA 104 - Level 3 B1/B2
FOR TRAINING PURPOSES ONLY
FUSELAGE GENERAL DESCRIPTION (CONT.)
General (cont.)
The bulkhead at Body Station 1088 incorporates the vertical fin rear spar attach fittings. A rectangular cutout in the web
allows the forward part of the horizontal stabilizer center section truss to protrude through it. The horizontal stabilizer
jackscrew mechanism is attached to the forward side of the bulkhead web.
A non-retractable tail skid is located between Body Stations 1064 and 1088. (737-400) The bulkhead at Body Station 1156
incorporates the horizontal stabilizer center section truss hinge joints. Elevator control mechanisms are attached to the aft
side of the bulkhead. The lower part of the bulkhead is cut away to allow for the APU exhaust pipe.
The fuselage stringers, which start at Body Station 259.5, are hat-section members along the entire fuselage. The continuity
of the stringers is maintained across the production joints in the fuselage structure by terminating the stringers on each
section at a fitting which is attached to the production joint frame. The keel beams comprise the beam between the main
landing gear wheel wells and the beam which passes beneath the center wing box. The beam between the wheel wells is a
reinforced box structure which carries pressurization loads originating on the sealed floor structure across the wheel well
area. Both of the beams carry the bending loads acting along the lower fuselage across the cavities for the center wing box
and the wheel well.
The fuselage skin varies in thickness according to the loads it must bear in any given area, and it is designed with fail-safe
features to ensure alternate load paths in the event of a local failure. The thickest skin panels are those over the area where
the lower fuselage is cut away to accommodate the wing and the main landing gear wheel well. In this area the skin panels
are machined from thick sheets. Many of the skin panels are attached to each other by bonded longitudinal lap joints, which
provide pressure seals in addition to being structural joints. Circumferential skin splices exist aft of the control cabin, at the
front spar bulkhead, at the bulkhead aft of the wheel well, and at the aft pressure bulkhead. The skin is reinforced by means
of doublers bonded to the inside of the outer skin. These doublers function as tear stoppers by forming a complete, integral
fail-safe, circumferential and longitudinal ―waffle‖ grid.
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Training Manual ATA 51-57 – Structures
Boeing 737-300/400/500 –CFM56-3 ATA 104 - Level 3 B1/B2
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-continued-
The fuselage structure around all door openings is reinforced to ensure adequate distribution of fuselage loads around the
opening. The passenger window openings are reinforced by doublers forming part of the inner waffled skin. The control cabin
window frames are reinforced fabrications of extruded sections.
Access panels are provided in the fuselage, refer to the Maintenance Manual, Chapter 12, Section 31, for location and
identification. Two overwing emergency exit doors are installed on each side of the fuselage. One between Body Stations
578 and 601, the other door between Body Stations 616 and 639. (737-400)
A horizontal beam extends along each side of the fuselage level with the top of the floor. These beams are known as the
crease beams because they are attached to the fuselage skin at the ―crease‖ formed by the intersection between the upper
and lower lobes of the fuselage cross-section.
The materials used for fuselage construction are:
- Frames - Aluminum Alloy 2024 and 7075
- Stringers - Aluminum Alloy 7075
- Keel beam - Aluminum Alloy 7075
- Skins - Aluminum Alloy 2024
- Floor beams - Aluminum Alloy 7075
- Radar Enclosure, APU tailcone - Fiberglass and Honeycomb
- APU exhaust area - Titanium
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Training Manual ATA 51-57 – Structures
Boeing 737-300/400/500 –CFM56-3 ATA 104 - Level 3 B1/B2
FOR TRAINING PURPOSES ONLY
ATA 57 WINGS
57-00 GENERAL
WINGS GENERAL DESCRIPTION
The structure of the wing supports the two wing mounted powerplants, the
flight controls and provides a lifting airfoil for the airframe. The wing also supports the main landing gear beams.
The structure of the wing between left and right tips consists of the left, center and the right wing boxes. The left and right
wing boxes are cantilevered from the center wing box which is enclosed within the fuselage. The thickness and chord of
each wing tapers down toward the tip and in plain view, both wings sweep back from the center wing box. The landing
gear support beam is attached at its outboard end to the rear face of the wing rear spar. Short struts underneath each
wing support the two powerplants.
Flight controls consist of slats, flaps, ailerons and spoilers and are attached at front and rear spars.
Vortex generators are installed on the upper wing surface.
The wing boxes and the center wing box consists of upper and lower skin panels, ribs and front and rear spars. The skin
panels are reinforced by spanwise stringers, the spars by vertical stiffeners, and the wing boxes by a series of chordwise
ribs. The center wing box is reinforced by spanwise beams. Access panels are provided in the wing. The landing gear
support beams are two-piece I-section forgings bonded and bolted together and connected at their outboard ends to the
left and right wing rear spars and at their inboard ends to the left and right sides of the fuselage.
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Training Manual ATA 51-57 – Structures
Boeing 737-300/400/500 –CFM56-3 ATA 104 - Level 3 B1/B2
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Leading Edge Slats
Three leading edge slats are installed on each wing outboard of the engine. The slats consist of ribs attached to a beam,
inner and outer skins and a trailing edge. A void between the inner and outer skins provides a path for thermal anti-icing.
Leading Edge Flaps
Two leading edge flaps are installed on each wing. Each flap is a machined casting containing integral ribs and stiffeners.
Trailing Edge Flaps
The inboard and outboard trailing edge flaps consist of a midflap, a foreflap, and an aftflap.
The inboard midflap consists of ribs, three spars, honeycomb trailing edge and skins.
The outboard midflap consists of ribs, two spars, a trailing edge beam, two honeycomb trailing edge panels and skins.
The foreflap is a monospar structure with a honeycomb trailing edge panel and skins.
The aftflap is also a monospar structure with a honeycomb trailing edge panel and skins.
Aileron
Each aileron is a frame structure consisting of leading and trailing edge spars, ribs and skin. An aileron tab is attached to
the rear spar of the aileron by four hinges. Ailerons together with flight spoilers provide roll control of the aircraft.
Spoilers
The spoiler panels are of graphite/epoxy construction. They are constructed with upper and lower skins and with a
honeycomb core. A continuous phenolic rubstrip is bonded to the lower surface at the trailing edge.
Attach Fittings - Wing Terminal Fitting
The wing terminal fitting is a heavy three-flanged forging. There are four of these fittings, the two forward ones and the two
aft ones. The flanges of the fitting act as a means of connection between the wing boxes and the center wing box. The wing
box to center wing box connection is accomplished by the use of the three flanges of the wing terminal fitting. The places of
connection are at the four corners of the center wing box where three main members join: a wing box spar, a center wing
box spar, and a wing root rib. At any one corner of the center wing box, the two spars and the wing root rib are attached to
the three flanges of the fitting.
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Training Manual ATA 51-57 – Structures
Boeing 737-300/400/500 –CFM56-3 ATA 104 - Level 3 B1/B2
FOR TRAINING PURPOSES ONLY
-continued-
Attach Fittings - Flight Controls
The aileron attachment fittings consist of hinge and actuation mechanism fittings and these are mounted on the aft side of
the rear spar and to structure mounted on that spar. The trailing edge flap attachment fittings on each wing consist
primarily of two pairs of flaptracks, one pair for each flap assembly.
Attach Fittings - Flight Controls (Cont)
The leading edge flap attachment fittings consist of hinge fittings mounted along the forward edge of the leading edge
structure. The leading edge slat attachment fittings consist of brackets which support the guide rollers and the actuators,
all of which are attached to the forward face of the wing front spar. The spoiler attachment fittings consist of hinge fittings
and the fittings which support the actuation mechanisms. The fittings associated with the outboard set of spoilers are
mounted on the aft face of the wing rear spar and those for the inboard spoilers are on the aft face of the wing rear spar
and landing gear support beam.
The wing is divided into reference planes measured in inches. This provides a means of identifying the location of
components or particular points. Two reference planes are used for the wing.
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Training Manual ATA 51-57 – Structures
Boeing 737-300/400/500 –CFM56-3 ATA 104 - Level 3 B1/B2
FOR TRAINING PURPOSES ONLY
WSTA - Wing Station
A plane perpendicular to the wing chord plane, and normal to the rear
spar, measured from the intersection of the wing leading edge line extension
and Wing Buttock Line 0.00.
WBL - Wing Buttock Line
A plane perpendicular to the wing chord plane and parallel to the body
buttock line. It is measured from intersection of wing chord plane and
Body Buttock Line 0.00.
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Training Manual ATA 51-57 – Structures
Boeing 737-300/400/500 –CFM56-3 ATA 104 - Level 3 B1/B2
FOR TRAINING PURPOSES ONLY
Materials
The materials used for construction of the wings are:
WING CENTER SECTION
- Beams - Aluminum Alloy 7178
- Stringers - Aluminum Alloy 2024
WING
- Spars - Aluminum Alloy 2024 and 7178
- Ribs — Aluminum Alloy 7075
- Upper Skin and Stringers - Aluminum Alloy 7150
- Lower Skin and Stringers Aluminum Alloy 2324 and 2224
VORTEX GENERATORS
- Aluminum Alloy 2024
LEADING EDGE SLATS
- Aluminum Alloy 2024
LEADING EDGE FLAPS
- Aluminum Alloy A356 (Casting)
TRAILING EDGE FLAPS
- Aluminum Alloy 2024 and Honeycomb
AILERON
- Graphite/Epoxy and Honeycomb
SPOILERS
- Graphite/Epoxy and Honeycomb
LANDING GEAR BEAM
- Aluminum Alloy 7175
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Training Manual ATA 51-57 – Structures
Boeing 737-300/400/500 –CFM56-3 ATA 104 - Level 3 B1/B2
FOR TRAINING PURPOSES ONLY
FIGURE 13
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Training Manual ATA 51-57 – Structures
Boeing 737-300/400/500 –CFM56-3 ATA 104 - Level 3 B1/B2
FOR TRAINING PURPOSES ONLY
ATA 54 NACELLES / PYLONS
54-00 GENERAL
STRUT
The engine struts are attached to the wing front spar and provide a structurally sound attachment point for the two airframe
powerplants.
The two engine struts are cantilevered from the front spar of each wing and are structurally similar but not interchangeable.
The basic structure consists of a torque box attached to the wing structure by linkages and braces with fuse pins. Engine
attachment points are located at forward and mid sections of the torque box. Between the two engine attachments are two
thrust links connecting the torque box to the engine. On the bottom section of the torque box is the engine firewall. Forward
of the torque box is the fan cowl support beam and forward fairing. Behind the torque box is the aft fairing, and the trailing
edge flap track fairing. Access panels are provided in the strut. Refer to the Maintenance Manual, Chapter 12, Section 31
for location and identification.
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Training Manual ATA 51-57 – Structures
Boeing 737-300/400/500 –CFM56-3 ATA 104 - Level 3 B1/B2
FOR TRAINING PURPOSES ONLY
Materials
The materials used for strut construction are:
TORQUE BOX
Aluminum Alloy 7075 and 2024
FIREWALL
Stainless Steel
FAN COWL SUPPORT BEAM SKIN AND FORWARD FAIRING
Graphite/Epoxy composite and Kevlar
AFT FAIRING
Aluminum Alloy and Aluminum Honeycomb
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Training Manual ATA 51-57 – Structures
Boeing 737-300/400/500 –CFM56-3 ATA 104 - Level 3 B1/B2
FOR TRAINING PURPOSES ONLY
FIGURE 14
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Training Manual ATA 51-57 – Structures
Boeing 737-300/400/500 –CFM56-3 ATA 104 - Level 3 B1/B2
FOR TRAINING PURPOSES ONLY
NACELLE
The nacelle provides an aerodynamically sound enclosure for the strut mounted engines. It provides for smooth airflow
around and into each engine while causing a minimum amount of drag. It also protects the components mounted on the
engine from physical damage from outside sources.
The nacelle, which encloses the engine, consists of the inlet cowl, fan cowls, thrust reverser, and trailing edge fairing.
The cowlings and thrust reverser fairing consist of frames and skins. The interior skin of the inlet cowl is treated with
sound suppression material.
The nacelle is divided into reference planes measured in inches. This provides a means of identifying the location of
components of particular points. Two reference planes are used for the nacelle.
NAC WL Nacelle Waterline
A plane 10 38’ down from the wing chord plane.
NAC STA Nacelle Station
Distance measured parallel to nacelle CL from a point 120.47 inches forward of the nacelle.
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Training Manual ATA 51-57 – Structures
Boeing 737-300/400/500 –CFM56-3 ATA 104 - Level 3 B1/B2
FOR TRAINING PURPOSES ONLY
Materials
Materials used in construction of the nacelles are:
INLET COWL
Aluminum Alloy 2024, Fiberglass and Aluminum Honeycomb
FAN COWLS
Kevlar, Graphite/Epoxy and Honeycomb
THRUST REVERSER FAIRING
Graphite/Epoxy and Aluminum Honeycomb
TRAILING EDGE FAIRING
Kevlar Honeycomb - Upper Stainless Steel Cap
44
Training Manual ATA 51-57 – Structures
Boeing 737-300/400/500 –CFM56-3 ATA 104 - Level 3 B1/B2
FOR TRAINING PURPOSES ONLY
FIGURE 15
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Training Manual ATA 51-57 – Structures
Boeing 737-300/400/500 –CFM56-3 ATA 104 - Level 3 B1/B2
FOR TRAINING PURPOSES ONLY
ATA 55 STABILIZER
55-10 HORIZONTAL STABILIZER
GENERAL DESCRIPTION
The horizontal stabilizer provides aerodynamic pitch trim and control of the airplane.
The horizontal stabilizer assembly consists of left and right outboard sections attached to a center section truss located
within the fuselage. The stabilizer pivoted on two hinge joints attached to a bulkhead in the fuselage. The angle of attack
is adjusted by means of an electrically driven or manually operated ballnut and jackscrew attached to the forward side of
the center section truss. An aerodynamic seal fills the gap between the stabilizer left and right outboard sections and the
fuselage. A sliding plate seal is located at points where the front and rear spars pass into the fuselage. A leading edge is
attached to the front spar. The trailing edge and elevator hinge structure is attached at the rear spar. Access panels are
provided in the horizontal stabilize refer to the Maintenance Manual, Chapter 12, Section 31 for location and
identification.
The front and rear spars, the ribs and the skin of the horizontal stabilizer outboard sections together with the center
section truss form a beam which is the main structural member of the stabilizer. Attachment of the outboard sections
and the center section is at the front and rear spars only, with no structural tie between the outboard section skins and
the center section.
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Training Manual ATA 51-57 – Structures
Boeing 737-300/400/500 –CFM56-3 ATA 104 - Level 3 B1/B2
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-continued-
The structure aft of the rear spar consists of ribs which incorporate hinge bearings for the elevator. The upper and lower
surfaces of the area between the rear spar and the elevator hinge bearings are covered by skin panels attached to the
ribs. Some of the skin panels are removable for maintenance purposes. The gimbals surrounding the jackscrew ballnut are
supported by a rigidly built-up framework of members on the forward face of the center section truss front spar. The basic
structure of the elevator is dual spar at the inboard end and monospar at the outboard end, with all areas reinforced with
ribs. The elevators are attached to hinge ribs extending aft from the rear spar of the stabilizer by elevator hinges on the
front spar of the elevator. The elevator balance panels project forward of the hinge line and are housed in the space
between the hinge ribs on the stabilizer rear spar. An elevator tab is attached to the rear spar of the elevator.
Empennage flight control surface attach fittings are aluminum alloy forgings. The fittings on which the horizontal stabilizer
outboard sections are mounted to the center section truss are at the inboard ends of the center section truss front and rear
spars. The fittings, incorporating the hinges on which the center section truss pivots are mounted on the aft face of the
truss rear spar and the bulkhead at Body Station 1156. Fittings associated with the elevators include elevator and tab
hinge fittings and fittings for the actuation mechanisms. The horizontal stabilizer is divided into reference planes measured
in inches. This provides a means of identifying the location of components or particular points.
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Training Manual ATA 51-57 – Structures
Boeing 737-300/400/500 –CFM56-3 ATA 104 - Level 3 B1/B2
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THREE REFERENCE PLANES ARE USED FOR HORIZONTAL STABILIZER
STAB STA Horizontal Stabilizer Station. A plane perpendicular to the stabilizer chord plane and normal to the stabilizer rear
spar, measured from Stabilizer Station 0.000, the intersection of the leading edge line extension and Body Buttock
Line 0.000.
STAB LE STA Horizontal Stabilizer Leading Edge Station. A plane perpendicular to the horizontal stabilizer leading edge,
measured from the Stabilizer Leading Edge Station 0.00, the intersection of the leading edge line extension and
Body Buttock Line 0.00.
ELEV STA Elevator Station. A plane perpendicular to the elevator hinge centerline measured from the intersection of elevator
hinge centerline and Body Buttock Line 0.00.
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Training Manual ATA 51-57 – Structures
Boeing 737-300/400/500 –CFM56-3 ATA 104 - Level 3 B1/B2
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FIGURE 16
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Training Manual ATA 51-57 – Structures
Boeing 737-300/400/500 –CFM56-3 ATA 104 - Level 3 B1/B2
FOR TRAINING PURPOSES ONLY
Materials
Materials used in construction of the horizontal stabilizer are:
STABILIZER
Spars and Ribs - Aluminum Alloy 7075
Skin - Aluminum Alloy 2024
Skin aft of rear spar - Kevlar and Honeycomb
ELEVATOR
Spar and Ribs - Aluminum Alloy 2024
Skin - Graphite/Epoxy
TAB
Spar - Aluminum Alloy 2024
Skin - Graphite/Epoxy
STABILIZER TRUSS
Aluminum Alloy - 7075
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Training Manual ATA 51-57 – Structures
Boeing 737-300/400/500 –CFM56-3 ATA 104 - Level 3 B1/B2
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FIGURE 17
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Training Manual ATA 51-57 – Structures
Boeing 737-300/400/500 –CFM56-3 ATA 104 - Level 3 B1/B2
FOR TRAINING PURPOSES ONLY
55-30 VERTICAL STABILIZER
GENERAL DESCRIPTION
The vertical stabilizer gives stability in the yaw axis for the airplane and provides for directional control with the use of a
rudder during takeoff and landing and for trim during cruise conditions.
The vertical stabilizer (fin) is attached to body Section 48 at two points. The leading edge is detachable. The dorsal fin is
not structurally connected to the main vertical fin. The fittings on which the vertical fin is mounted are at Body Stations
1016 and 1088 and Fin Waterline 0.
The front and rear spars, the ribs and the skin of the vertical fin form a beam which is the main structural member of the
fin. The structure aft of the rear spar consists of ribs which incorporate hinge bearings for the rudder. The left and right
surfaces of the area between the rear spar and the rudder hinge bearings are covered by skin panels attached to the
ribs to form a trailing edge fairing. A removable leading edge structure is attached to the forward side of the fin front
spar. A fairing is attached at the top of the fin. Access panels are provided in the vertical stabilizer, refer to the
Maintenance Manual, Chapter 12, Section 31 for location and identification.
The rudder structure consists of a complete front spar and a partial rear spar, chordwise ribs, and skin panels. The
rudder has hinge fittings forward of its front spar. Forward of the rudder front spars are leading edge fairings and nose
sections, which are housed within the vertical fin trailing edge fairing. In one nose section is located a rudder balance
weight. The vertical stabilizer is divided into reference planes measured in inches. This provides a means of identifying
the location of components or particular points.
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Training Manual ATA 51-57 – Structures
Boeing 737-300/400/500 –CFM56-3 ATA 104 - Level 3 B1/B2
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Four reference planes are used for the vertical stabilizer.
FIN STA - Vertical Stabilizer Station
The plane perpendicular to the center line of the vertical stabilizer rear spar, measured from Fin
Station 0.00, the intersection of the leading edge line extension and Fin Waterline 0.00.
FIN WL - Vertical Stabilizer Waterline
A horizontal plane measured parallel to a Body Waterline. Fin Waterline 0.00 is Body Waterline
300.50.
FIN LE STA - Vertical Stabilizer Leading Edge Station
A plane perpendicular to the vertical stabilizer leading edge, measured from the Fin Leading Edge
Station 0.00, the intersection of the leading edge line extension and Fin Waterline 0.00.
RUD STA - Rudder Station
A plane perpendicular to the rudder hinge centerline, measured from Rudder Station 0.00, the
intersection of the rudder hinge centerline and Fin Waterline 0.00.
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Training Manual ATA 51-57 – Structures
Boeing 737-300/400/500 –CFM56-3 ATA 104 - Level 3 B1/B2
FOR TRAINING PURPOSES ONLY
Materials
Materials used in construction of the vertical stabilizer are:
STABILIZER
Spars and Ribs - Aluminum Alloy 7075
Skin - Aluminum Alloy 2024
Skin aft of rear spar - Kevlar and Honeycomb
DORSAL
Ribs - Aluminum Alloy 2024
Skin - Graphite/Epoxy and Honeycomb
RUDDER
Spar and Ribs - Aluminum Alloy 2024
Skin - Graphite/Epoxy and Honeycomb
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Training Manual ATA 51-57 – Structures
Boeing 737-300/400/500 –CFM56-3 ATA 104 - Level 3 B1/B2
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FIGURE 18
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Training Manual ATA 51-57 – Structures
Boeing 737-300/400/500 –CFM56-3 ATA 104 - Level 3 B1/B2
FOR TRAINING PURPOSES ONLY
ATA 52 DOORS
52-00 GENERAL
INTRODUCTION
The purpose of the doors is to permit entry to or exit from the various airplane compartment and areas.
Entry Doors:
- Provide for entry and exit for passengers and crew members. Located on the left side, forward and aft.
Galley Service Doors:
- Located forward and aft on the right side, they are normally used for servicing the galleys. They also serve as
emergency exits.
Emergency Exits:
- The overwing emergency hatches are available as emergency exits on both sides.
Cargo Compartment Doors:
- Provide access to the cargo compartments; located forward and aft of the wing on the right side.
External Service Doors:
- These doors are used by ground personnel for maintenance and servicing. The two doors in the pressurized portion
are located in the lower fuselage forward and aft of the nose gear.
The flight compartment door is a secure door controlled by the flight crew. It provides positive separation between the
flight compartment and passenger compartment.
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Training Manual ATA 51-57 – Structures
Boeing 737-300/400/500 –CFM56-3 ATA 104 - Level 3 B1/B2
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FIGURE 19
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Training Manual ATA 51-57 – Structures
Boeing 737-300/400/500 –CFM56-3 ATA 104 - Level 3 B1/B2
FOR TRAINING PURPOSES ONLY
FIGURE 20
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Training Manual ATA 51-57 – Structures
Boeing 737-300/400/500 –CFM56-3 ATA 104 - Level 3 B1/B2
FOR TRAINING PURPOSES ONLY
52-10 PASSENGER / CREW
ENTRY DOOR
The purpose of the entry doors is to provide the primary entrance and exit for the passengers and flight crew.
The entry doors are located on the left side of the airplane at the fore and aft ends of the passenger compartment.
The forward entry door is 34 inches wide and 72 inches high, the aft entry door is 30 inches wide and 72 inches
high. Both are inward - outward opening plugtype doors. An upper and lower hinge assembly support the door on
its forward edge; the doors may be closed or opened from inside or outside the airplane.
The door is opened by manually operating the centrally located handle. This action causes the internal
mechanism to release the latches, folds the gates inward, and moves the door to its most inward position. The
door is manually swung through the door opening and stowed in the open position forward of the opening.
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Training Manual ATA 51-57 – Structures
Boeing 737-300/400/500 –CFM56-3 ATA 104 - Level 3 B1/B2
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FIGURE 21
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Training Manual ATA 51-57 – Structures
Boeing 737-300/400/500 –CFM56-3 ATA 104 - Level 3 B1/B2
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FIGURE 22
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Training Manual ATA 51-57 – Structures
Boeing 737-300/400/500 –CFM56-3 ATA 104 - Level 3 B1/B2
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ENTRY DOOR MECHANISM
The entry door mechanism consists of several assemblies that accomplish the following functions:
Handle Mechanism:
- This mechanism, through a duplex arm, converts the rotary motion of the handles to a push-pull motion of two cranks.
One crank actuates the latches, and upper and lower gates during initial handle rotation. The other crank moves the
forward edge of the door inward to its open position during further rotation.
Door stops and latching assembly:
- These devices transmit pressure loads from the door to body structure, and latch the door in the closed position.
Centering Guide:
- A pin on the aft edge of the door slides into a guide track on the frame to align the stops and latches.
Lower Hinge:
- A rigid hinge arm is attached to the lower end of both the body and door torque tube assemblies. A hydraulic snubber
impedes door movement at its travel extremities.
Upper Hinge:
- A rigid hinge arm is attached to the body and door torque tube assembly.
A guide arm parallel to the hinge arm rides in an ―S‖ shaped track to control the door rotation about its torque tube.
Spring Assist Torque Tube (counterbalance assembly):
- The upper and lower hinge arms are attached to a vertical, body mounted torque tube to support the door when it is
open. Torsion springs around this torque tube provide opening and closing assistance.
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Training Manual ATA 51-57 – Structures
Boeing 737-300/400/500 –CFM56-3 ATA 104 - Level 3 B1/B2
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FIGURE 23
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Training Manual ATA 51-57 – Structures
Boeing 737-300/400/500 –CFM56-3 ATA 104 - Level 3 B1/B2
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FIGURE 24
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Training Manual ATA 51-57 – Structures
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FIGURE 25
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Training Manual ATA 51-57 – Structures
Boeing 737-300/400/500 –CFM56-3 ATA 104 - Level 3 B1/B2
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FIGURE 26
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Training Manual ATA 51-57 – Structures
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FORWARD ENTRY DOOR OPERATION
Two cam rollers are moved by a cam plate that is rotated by the door handle action. This action provides the force
required to operate the latches, the upper and lower gates and orient the door through the opening by the torque tube.
The camming action is transmitted by pushrods to the latches, torque tube and end gates by control rods.
The aft entry door operates in the identical manner.
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Training Manual ATA 51-57 – Structures
Boeing 737-300/400/500 –CFM56-3 ATA 104 - Level 3 B1/B2
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FIGURE 27
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Training Manual ATA 51-57 – Structures
Boeing 737-300/400/500 –CFM56-3 ATA 104 - Level 3 B1/B2
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CAM PLATE OPERATION
Unlatching
Initial rotation of the cam plate transmits angular movement to the latching crank assembly. The control rods at each end
of the latching crank, turn the latch rods and withdraw the latch rollers. The latch rods also operate the control rods
attached to the upper and lower gates, causing them to fold inward. These control rods all have adjustable end bearings
for latch and gate rigging. During this initial movement, the cocking crank roller is riding on a surface of constant radius
from the cam plate pivot center; no angular movement is imparted to the cocking crank assembly.
Cocking
Rotation of the cam plate to its full travel transmits angular movement to the cocking crank assembly. The cocking crank
operates the push rod connected to the torque tube. An adjustable end bearing on the cocking crank pushrod moves the
door laterally for latch engagement rigging. Movement of the pushrod is resisted by the torque tube, causing the door to
rotate and pivot about the torque tube axis.
Opening
The door is swung forward through the opening manually until the door is approximately parallel with the airplane exterior.
The door will lock in this position
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Training Manual ATA 51-57 – Structures
Boeing 737-300/400/500 –CFM56-3 ATA 104 - Level 3 B1/B2
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FIGURE 28
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Training Manual ATA 51-57 – Structures
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UPPER HINGE / GUIDE ARM GEOMETRY
Operation
As the cam plate is rotated by the handle, the cocking crank pushrod rotates the door torque tube and upper hinge arm
counterclockwise (viewed from above). This moves the door inward. The guide arm at the upper hinge, riding in the ―S‖
shapes cam track, changes the hinge geometry causing the door to rotate about the door torque tube to the cocked
position. From the cocked position, the door is manually swung to its fully open position pivoting about the body torque
tube. The guide arm causes the door to also pivot about the door torque tube so that it is parallel to the fuselage when fully
open. The guide arm end bearing is adjustable to fair the door with the fuselage.
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Training Manual ATA 51-57 – Structures
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FIGURE 29
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52-40 SERVICE
GALLEY SERVICE DOOR
The purpose of the galley service doors is to provide an entrance for servicing the airplane galleys on the right side of the
airplane. They may also be used as a secondary entrance and exit for passengers and crew.
The galley service doors are located on the right side of the airplane at the fore and aft ends of the passenger
compartment.
The galley service doors are 30 inches wide and 65 inches high. Except for the size, the physical description and features
of the galley service doors are the same as the entry doors.
The operation of the galley service doors is identical to the entry doors.
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Training Manual ATA 51-57 – Structures
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FIGURE 30
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Training Manual ATA 51-57 – Structures
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LOWER NOSE COMPARTMENT ACCESS DOOR
The purpose of the lower nose compartment access door is to permit access to the compartment below the flight
compartment. Many flight control cables and brake accessories pass through this area.
The lower nose compartment access door is located in the bottom of the fuselage forward of the nose wheel well and aft of
the radome.
The door is an inward opening, plug-type door that can be opened only from outside the airplane. Two hinge arms extend
aft from the door to hinge fittings on the forward face of the nose wheel well forward bulkhead. The door latching
mechanism consists of a latch pin which protrudes through the forward edge of the door to engage a hole in the fuselage
structure.
The door is opened from outside the airplane by pushing the trigger in the door handle; the handle springs out from its flush
position. Rotating the handle counterclockwise retracts the latch pin and allows the door to be hinged upward. When the
door is closed, a clockwise rotation of the handle pushes the latch pin into the structure forward of the door. The handle
must be pushed back flush with the door skin.
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Training Manual ATA 51-57 – Structures
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FIGURE 31
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ELECTRONIC EQUIPMENT COMPARTMENT ACCESS DOOR
The purpose of the electronic equipment compartment access door is to permit access into the compartment containing the
avionics, the battery, and the dc external power connection.
The electronic equipment compartment door is located aft of the nose wheel well and forward of the wings in the bottom of
the fuselage.
The electronic equipment compartment external access door is a plug-type, inward opening, sliding door on the bottom side
of the fuselage aft of the nose wheel well. The door is operated from outside the fuselage and is included in the door
warning system, sharing a common warning light in the control cabin with the lower nose compartment access door. The
door tracks inside the fuselage guide the door inward, upward, and to the right. The door has an alclad frame and skin
construction. A continuous seal around the periphery of the door prevents loss of cabin air when the airplane is in flight.
Four latch pins transmit pressurization loads from the door to the fuselage structure. The stop fittings on the door and the
door lock fittings on the structure will transmit the pressurization loads if the door is accidentally not latched. Rollers at the
end of an angle on the door engage with roller guides on the fuselage to keep the door in position.
Latch Mechanism
The door latching mechanism has a latch stop and lock fitting on each side of the door. The latch pins are operated through
a common rack and pinion mechanism. The inner end of each pin is in the form of a rack and all four racks engage with
a pinion on the central actuator shaft. The shaft has an outer handle to operate the door from outside the airplane.
Door Tracks
The door tracks are inclined upward and outboard from door opening. The door tracks are attached to the electronic rack
supports and the electronic rack stanchions.
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Top and Bottom Web Assembly
The bottom web holds the door when you move it up the tracks. Flexible leaf-spring brackets attach the bottom web to the
door. The top and bottom webs have eight rollers which keep the webs between the door tracks. The bottom web retracts
into the top web as the door moves to its stowed position.
Uplatch (if installed)
An uplatch is on the inner right side of the door. The uplatch holds the door to the bottom web as it is retracted. The uplatch
engages the latch pin after you move the door up and to the right 1/2 to 1 inch. A lever disconnects the uplatch from the
bottom web as you close the door. If you let the door roll to the left when it is opened, the door will disengage from the
tracks. A cable assembly with a spring in the door decreases the rate of fall of the door after the uplatch releases the door. A
guard over the striker prevents accidental release of the uplatch.
Spring Spool Assembly
The spring spool assembly helps to retract the door and holds the door in the open position. The assembly is attached to
the fuselage at the end of the tracks.
Airplane with an Uplatch
One end of the flat spring is attached to the bottom web.
Airplane with a Trolley
One end of the flat spring is attached to a hinge on the trolley.
Trolly if installed
The trolley moves in a track to support the right side of the door and direct it as it moves to its stowed position.
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FIGURE 32
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ELECTRONIC EQUIPMENT COMPARTMENT ACCESS DOOR
(CONT)
Operation
OPEN THE DOOR FROM OUTSIDE THE AIRPLANE:
Push the trigger in the outer handle, to get access to the handle.
-A spring will push the handle from its flush position.
Turn the handle counterclockwise.
-The four latch pins will retract into the door.
-The door warning lights in the control cabin will come on.
Push the door up and to the right.
- The right side of the door will pivot about the track attach brackets on the left side of the door.
Airplanes with an Uplatch
-The uplatch, on the right side of door, engages the latch pin on bottom web.
Move the door up the track to its stowed position.
- The door will move easily with help from the assist spring.
CLOSE THE DOOR FROM OUTSIDE THE AIRPLANE:
Pull the door down the tracks with the handle.
Airplane with an Uplatch
-At the bottom of the track, the lever will disengage the uplatch, and release the door from the bottom web.
Make sure the door is seated correctly.
Pull down on the door handle to compress the door pressure seal and turn
the handle clockwise.
- The four latch pins will lock the door in its closed position.
-The door warning lights in the control cabin will go off.
Push the handle up to its flush position.
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FIGURE 33
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52-20 EMERGENCY EXIT
EMERGENCY EXIT HATCH
The purpose of the emergency exit hatch is to provide a means of exiting the passenger compartment in the event of an
emergency.
These identical hatches are located on each side of the fuselage at the overwing area.
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FIGURE 34
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EMERGENCY HATCH DETAILS
The hatches are 20 inches wide by 38 inches high and are classified as Type III emergency exits. The hatches are plug-
type and can be opened from inside or outside the airplane. Each hatch is supported by a lower pivot fitting which
engages a lower pivot hook on the sill of the opening. Two heel pads attached the hatch rest on the sill. The handle is an
integral casting formed with a pull- lever on the inside and a push-type panel on the outside. The lower end of the handle
is attached to a torque tube; on each end of the torque tube is a latch roller which engages the latch fittings attached to
the forward and aft frames of the hatch opening. Adjustable stop pins attached to the forward and aft edges of the hatch
contact stop fittings attached to the forward and aft frames of the hatch opening. The stops transmit the pressurization
loads on the hatch to the fuselage structure.
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FIGURE 35
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FIGURE 36
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EMERGENCY EXIT HATCH OPERATION
Inside Removal
The hatch is opened from the inside by pulling down and in on the handhold pocket which is attached to the operating
handle. The action of the handle rotates the torque tube and turns the latch rollers. The latch rollers disengage from the
latch fittings and the top edge of the hatch moves inward.
Continuing to hold the upper handle, the lower handhold is grasped with the other hand and the hatch is pulled inward at
the top edge. The hatch is then lifted upwards and inwards away from the opening, disengaging the lower pivot fitting from
the lower pivot hook.
Outside Removal
The hatch is opened from the outside by pushing in on the panel at the top of the hatch and then pushing the hatch into
the airplane.
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FIGURE 37
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52-30 CARGO
CARGO COMPARTMENT DOORS
The purpose of the cargo compartment doors is to provide access to the forward and aft cargo compartments. The forward
cargo compartment door also permits access to the flight crew oxygen cylinder.
The cargo compartment doors are located on the right side of the airplane; the forward cargo compartment door is forward
of the wing and the aft cargo compartment is aft of the wing.
Both cargo compartment doors are plug-type, inward opening, manually operated, and hinged at the upper edge. Both
doors are the same in design and operation; however, they are not interchangeable. The forward door is 48 inches wide by
35 inches high and the aft door is 48 inches wide by 33 inches high.
Each door is hinged from the fuselage structure by two hinge arms on the upper edge. Pressurization loads are
transmitted to the fuselage by twelve stop fittings. Each door is equipped with a balance mechanism to counterbalance
the weight of the door. A snubber is installed between the hinge arms to restrain the free—fall of the door if the balance
mechanism cable fails.
Latch Mechanism
The door latching mechanism consists of two latching rollers, one at each end of a horizontal torque tube. The latching
rollers engage latch fittings attached to the fuselage. The torque tube is connected to the operating handle assembly.
The operating handle assembly has a handle on the inside of the door and a handle on the outside. The inside handle is
stationary but the outside handle is spring-loaded so that it retracts flush with the door when released after use.
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Balance Mechanism
Balance Mechanism on airplanes with an uplatch,
- door balance is maintained by springs attached to the upper aft inner edge of the door between the inner web and outer
skin.
- The springs connect to a cable assembly wound on a cable drum mounted on the forward inner structure of the door. From
the cable drum, the cable runs over two pulleys mounted on the inner structure of the door and connects to an overhead
floor beam.
- The cable grooves in the cable drum have a decreasing radius in order to provide a constant tension in the cable system as
the door is opened and closed.
- The balance mechanism is arranged so that the springs are stretched when the door is closed. When the door is opened,
the springs contract to raise the door to or near the open latched position.
On airplanes with a counterbalance assembly,
- door balance is maintained by a spring-driven idler crank that drives a cam fixed to a cable drum.
- The springs, idler crank, cam and drum are all located in the counterbalance assembly mounted on the inner structure of
the door.
- From the drum the cable runs over a pulley mounted on the inner structure of the door and connects to an overhead floor
beam.
- The counterbalance mechanism is arranged so that the springs are compressed when the door is closed.
- When the door is opened the springs extend to drive the idler crank, cam and drum to raise the door.
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FIGURE 38
Airplane with Uplatch
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FIGURE 39
Airplane with Counterbalance
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FIGURE 40
Airplane with Counterbalance
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CARGO DOOR OPERATION
The door is opened from outside the airplane by pulling the door handle out of the recess and rotating the handle
counterclockwise. Rotation of the handle actuates a torque tube to withdraw the latch rollers from the latch fittings. As the
door swings inboard, under tension of the door balance mechanism, the door warning proximity switch is actuated to
energize the appropriate door warning light in the control cabin.
As soon as the door has moved clear of the latch fittings, the handle may be released. springs within the handle will cause
the handle to return to the normally locked and recessed position. With little manual effort, the door may be swung open to
the open latch position.
On airplanes with an uplatch,
- the door is latched open when the spring-loaded mechanical latch on the lower edge of the door engages with a fitting
under the fuselage floor structure.
On airplanes with counterbalance assembly,
-the idler crank engages a detent on the cam inside the counterbalance assembly to latch the door open.
The door may be opened from inside the airplane, using the nonretracting inner handle. In this case, the procedure is similar
except that rotation of the handle appears clockwise to the operator.
Access to the inside handle is obtained by pulling aside the cargo net which extends from the ceiling to the lower edge of the
door.
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On airplanes with an uplatch,
- the door is closed by pulling on the lanyard to release the latch. The lanyard is adjacent to the cargo retaining net just
inside and forward of the door opening and is accessible to personnel standing on the ground.
- The lanyard design requires that the handle must be pulled outside the door opening before the latch will disengage.
- After the latch is disengaged, a continued pull on the lanyard brings the door down until the operating handle is within
reach. The handle is then lifted out of the recess. The lanyard is then released to return to normal position within the cargo
compartment.
- Counterclockwise rotation of the operating handle aligns the latch rollers with the latch fittings and allows the door to be
pulled down and latched by a clockwise rotation of the handle. This final movement engages both latch rollers in the fittings
and actuates the door warning proximity switch to de-energize the appropriate warning light in the control cabin. When the
door is thus closed and latched, the handle may be released.
On airplanes with counterbalance assembly,
- the door is closed by pulling on the lanyard to move the door down until the operating handle is within reach.
- The handle is then lifted from its recess and the lanyard is released. Counterclockwise rotation of the operating handle
aligns the latch rollers with the latch fittings and allows the door to be pulled down and latched movement engages both latch
rollers in the fittings and actuates the door warning proximity switch to de-energize the appropriate warning light in the
control cabin.
- When the door is thus closed and latched, the handle may be released.
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FIGURE 41
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FLIGHT COMPARTMENT DOOR EMERGENCY EXIT FEATURE
An emergency exit feature is provided which permits the release and removal of the two upper blowout panels from the door.
The removal of the two upper panels permits an emergency exit through the door. The emergency exit door release handle
is located on the forward side of the door between the two upper blowout panels. The release handle is grasped and pulled
forward. This movement of the handle operates a cable assembly and linkage which disengages retaining pins located on
each side of the handle at the door channel and allows the release handle to move forward.
The panels are then pulled forward of the door structure and allowed to drop. The panels are free of the door structure and
the emergency exit is available for use. The first observer’s seat can be released from stowed position and used as a step
when using the emergency exit in the door.
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FIGURE 42
Control Cabin Door (Front Side)
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FLIGHT COMPARTMENT DOOR LOCK
Power
The source of power for the electric feature of the flight compartment door lock is 28 volt dc bus No. 2.
Control
Control of the electric door lock is through a switch/light located on the aft P8 panel.
Operation
When the switch/light is illuminated, the door is unlocked. The door can be opened with a pull of 10 pounds, minimum.
When the switch/light is pressed, and the light extinguishes, the electric strike in the door frame is energized and the door is
locked.
Flight Compartment Doors are changed by new improved Flight Security Doors
within FAA regulative
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FIGURE 43
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DOOR LOCK OPERATION
Unlocked
When the door is unlocked, the striker will pivot out of the way when a force of 10 pounds is exerted to open the door from
the passenger compartment. From the flight compartment, the door may be opened by either pushing aft or turning the
knob.
Locked
When the switch/light on the P8 panel is pressed and the light extinguishes, the solenoid in the door frame is energized and
a shear pin is driven into a recess in the striker. The striker is now held rigid and the door is locked. The shear pin will break
if a force greater than 250 pounds is exerted. The door can be opened without breaking the shear pin by retracting the latch
bolt in the door with a key or turning the door knob. The key must be used when opening the door from the passenger
compartment and the door is locked. From the flight compartment, the latch bolt can be withdrawn by turning the door knob.
In the event of a power failure, the solenoid will de-energize and the shear pin will drop from the recess in the striker. The
door will be unlocked and can be opened in the normal manner.
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FIGURE 44
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FLIGHT COMPARTMENT DOOR EMERGENCY EXIT FEATURE
Operation
An emergency exit feature is provided which permits the release and removal of the two upper blowout panels from the door.
The removal of the two upper panels permits an emergency exit through the door. The emergency exit door release handle
is located on the forward side of the door between the two upper blowout panels. The release handle is grasped and pulled
forward. This movement of the handle operates a cable assembly and linkage which disengages retaining pins located on
each side of the handle at the door channel and allows the release handle to move forward.
The panels are then pulled forward of the door structure and allowed to drop. The panels are free of the door structure and
the emergency exit is available for use. The first observer’s seat can be released from stowed position and used as a step
when using the emergency exit in the door.
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FIGURE 45
Control Cabin Door (Front Side)
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FIGURE 46
Control Cabin Door Emergency Exit Panels Installation
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52-70 DOOR WARNING
DOOR UNLOCK INDICATORS
The individual warning lights for the doors are located on the overhead panel, P5. The electronic equipment compartment
access door and the lower nose compartment door activate the same light, EQUIP, through individual microswitches. The
circuit is such that both doors must be latched in order to extinguish the warning light. The other warning lights are activated
by sensors operated by each individual door.
When a door is unlatched, the sensor or microswitch completes a circuit and illuminates the appropriate warning light on the
P5 panel. Closing and latching the door will extinguish the warning light. When all of the doors are closed and latched, the
DOORS annunciator light will extinguish.
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FIGURE 47
Door Unlock Indication
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FIGURE 48
Door Warning System Schematic
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ATA 56 WINDOWS
56-00 GENERAL
INTRODUCTION
The purpose of the airplane windows is to provide:
- Visual means to fly the airplane and for collision avoidance,
- emergency exit from the flight compartment,
- and an opening in the opaque fuselage through which the environment may be viewed.
The windows on the airplane are grouped as follows:
- Flight Compartment windows
- Passenger Compartment windows
- Inspection windows
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FIGURE 49
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56-10 FLIGHT COMPARTMENT
FLIGHT COMPARTMENT WINDOWS
There are ten windows symmetrically located around the flight compartment. Windows No. 1, 3, 4 and 5 are fixed in
place. Window No. 2 is a sliding window, mounted on tracks, to permit ventilation and communication on the ground.
The construction of control cabin windows No. 1 and No. 2 consists of a glass pane laminated to each side of a polyvinyl
butyral (vinyl) interlayer or core. The inner glass pane is the thicker of the two and is the primary load carrying member.
The vinyl interlayer acts as the ―fail-safe‖ load carrying member and prevents the window from shattering if the inner
pane should break. The outer pane has no structural significance, but provides rigidity and a hard, scratch resistant
surface. A thin strip of parting medium is laminated around the window edges between the vinyl interlayer and each
glass pane. This is to prevent edge chipping of the glass under conditions of differential expansion and contraction.
A conductive coating of indium oxide applied on the inner face of the outer glass pane permits electrical heating for anti-
icing and defogging. The construction of No. 3 window consists of two stretched acrylic panes separated by a phenolic
spacer. The spacer is attached to the perimeter of the panes by pressure sensitive tape which also acts as an air seal.
The spacer provides an insulation cavity which prevents fogging on the inner surface of the windows. There is a small
hole in the upper forward corner of the inner pane. This hole must be open at all times to allow pressure in the air space
to equalize with pressure in the cabin.
Windows No. 4 and No. 5 are similar in construction in that both consist of a glass pane laminated to each side of a
polyvinyl butyral core. A conductive film, applied on the outer face of the inner glass permits electrical heating for
antiicing and defogging. No. 4 window, however, has an additional vinyl layer laminated to the inboard surface of the
inner pane. A cast acrylic sheet 15 laminated to the additional vinyl layer. These additional layers prevent glass from
scattering throughout the cabin in the event of bird impact. The additional layers are of no structural importance. A thin
parting medium is laminated around the window edges between the vinyl interlayers and each glass pane.
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This is to prevent edge chipping of the glass under conditions of differential expansion and contraction. The window seals
which are used on the flight compartment windows consist of fixed window pressure seals, which are used on windows No.
1, 3, 4, and 5, and the sliding window pressure seals installed on windows No. 2. The primary purpose of the two types of
pressure seals is to prevent cabin pressurization leakage around the windows when the airplane is pressurized. The
sealants that are used on the windows prevent moisture penetration, water entrapment, and provide aerodynamic flushness
of the outer windowpane with the window frame.
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FIGURE 50
Flight Compartment Windows Construction (Config.1)
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WINDOW NO. 1
The No. 1 window is pressure sealed on installation by means of a gasket-like, molded-in-place rubber seal. The beaded
silicon rubber seal surface mates with the window frame to ensure an effective pressure and moisture-tight seal. The
pressure seal is an integral part of the window assembly and, in combination with a formed stainless steel Z-channel strip, is
bonded to the periphery of the windshield glass. Removal and installation should not be attempted without consulting the
current Maintenance Manual. Replacement windows are supplied with the necessary
parts for installation and with both sides of the pane covered with a protective
coating.
To remove a No. 1 window, not only must the window fasteners be removed but also any trim panels, crash padding,
windshield wipers, the light shield (P7 panel), sunshade support rod, drain tube clamps, and drain pan must also be
removed. Pressure is applied to the window from the outside, pushed into the cabin, and removed.
Some general precautions to observe include:
- Use only non-magnetic bolts along the top, bottom and forward edges of the window because of the proximity to the
standby compass.
-Use a staggered sequence, diagonally back and forth across the window, to tighten each nut to the correct torque value.
Damage to the window may result if the correct torque is exceeded. Consult the Maintenance Manual for the proper torque
values and a recommended staggered sequence.
IMPORTANT NOTE: PRIOR TO PERFORMING ANY MAINTENANCE OR CLOSE
INSPECTION ON THE CONTROL CABIN WINDOWS, BE CERTAIN THAT ELECTRICAL
POWER HAS BEEN REMOVED. BE CAREFUL WHEN WORKING ON THE WINDOW
SINCE THE OUTPUT VOLTAGE OF THE AUTO-TRANSFORMER RANGES FROM 250 TO
350 VOLTS.
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FIGURE 51
WINDOW NO. 1
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WINDOW NO. 3 (CONFIG 1)
Window No. 3 consists of two stretched acrylic panes separated by a phenolic spacer. The rubber cushion strip is bonded
to the metal backing plate. On installation, the strip is allowed to compress the window assembly so as to make a weather
seal from the pressure seal.
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FIGURE 52
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WINDOWS NO. 4 & 5
Windows No. 4 & 5 are similar in construction; No. 4 has the additional inner layers for bird strike protection. No. 5 has the
thermal switch bracket which must be aligned with the thermal switch location etched on the glass. When installing the
windows, consult the Maintenance Manual for the recommended staggered sequence for tightening the self-locking nuts.
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FIGURE 53
Window No. 4 & 5 Installation
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WINDOWS NO. 2
The No. 2 windows are mounted on tracks so that they may be rolled back to permit ventilation and communication during
ground handling operations. The laminated window pane, inner and outer glass separated by a vinyl core, has the
conductive film between the outer pane and the core where it is most effective for anti-icing. Mounted on the window frame,
at top and bottom, are glides which are guided along tracks attached to the airframe above and below the window. A
clothing guard covers the link mechanism along the lower edge of the window. The window can be removed by positioning
the lower glides with the track lip cutout.
To open the window, the trigger is squeezed and the handle rotated back and inboard. This rotates a bellcrank, which is
linked to other bellcranks at rear top and bottom of window, drawing the window inboard. The window may be moved to the
rear until the lower aft glide travels past the window open latch plate which is spring-loaded to lock the window in the open
position. To close the window, slide forward until the handle can be rotated forward and outboard. As the handle is rotated,
the window is moved outboard tightly against the window frame. The first officer’s window can be opened from the outside
on the passenger airplane. On a cargo airplane, both the captain’s and the first officer’s windows can be opened from the
outside.
IMPORTANT NOTE: PRIOR TO PERFORMING ANY MAINTENANCE OR
CLOSE INSPECTION ON THE CONTROL CABIN WINDOWS, BE CERTAIN
THAT ELECTRICAL POWER HAS BEEN REMOVED. BE CAREFUL WHEN
WORKING ON THE WINDOW SINCE THE OUTPUT VOLTAGE OF THE AUTO-
TRANSFORMER RANGES FROM 250 TO 350 VOLTS.
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Boeing 737-300/400/500 –CFM56-3 ATA 104 - Level 3 B1/B2
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FIGURE 54
Right Window No. 2
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56-20 PASSENGER COMPARTMENT
FUNCTIONAL DESCRIPTION
Passenger compartment windows are located between the fuselage frames in those areas where passenger seating is
provided.
The passenger compartment windows consist of outer, middle and inner panes. The inner pane is nonstructural and is
mounted in the sidewall lining. The outer and middle panes are each capable of taking the full cabin pressurization load.
Fail-safe structure is ensured by the middle pane which is designed for 1.5 times the normal operating pressure at 70
degrees Fahrenheit. The passenger compartment windows are plug-type windows. Installation and sealing of the
windows is through the use of a molded ethylene propylene seal. The outer pane of stretched acrylic plastic is
rectangular in shape with rounded corners and a beveled outer edge. The pane is curved to fair with the fuselage
contour. The middle pane of modified acrylic plastic sheet is similarly shaped but with an unbeveled edge. A small
breather hole is located near the bottom of the middle pane. Ten window retaining clips secure the window in the window
frame.
When installing the window, the entire window assembly is placed in the window frame. After the retaining clips are
installed loosely, the protective cover is grasped at least two inches from the edge and pulled towards the center. The
seal adheres to the outer surface of the outer pane. The clip adjusting screws are then tightened using a criss-cross
torque sequence. The seal protective cover is removed by cutting the cover on the notch center line following the
instructions in the Maintenance Manual carefully. The cover is then torn off at the notch line.
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Training Manual ATA 51-57 – Structures
Boeing 737-300/400/500 –CFM56-3 ATA 104 - Level 3 B1/B2
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FIGURE 55
Passenger Cabin Window
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Boeing 737-300/400/500 –CFM56-3 ATA 104 - Level 3 B1/B2
FOR TRAINING PURPOSES ONLY
SEAL LEAK DETECTION
Seal leakage is indicated if there is a pattern of smoke impingement on the outer window outboard of the breather hole in the
middle window. If leakage is indicated at the outer window it is advisable to change the middle panel and the seal/spacer. If
the seal leaks excessively, the middle window carries the pressurization load; this can cause structural deterioration.
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Boeing 737-300/400/500 –CFM56-3 ATA 104 - Level 3 B1/B2
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FIGURE 56
Seal Leak Detection
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EDGE DAMAGE
No surface chips are allowed in the middle pane. Small, shell shaped, edge chips no greater than 0.06 inch in the maximum
dimension are permissible. V-shaped edge chips shall be cause for removal of the middle pane. Creep deformation is middle
pane damage created by window clip against the edge of pane. Deformation is permissible within the following limits:
Without noticeable surface discontinuity, surface or edge is slightly displaced, but a fingernail cannot detect a discontinuity.
Noticeable discontinuity, but no evidence of a vee notch crack, window should be reworked. Surface discontinuity and a vee
notch crack less than 0.05 inch inward from edge of pane, window should also be reworked. If crack is greater than 0.05 inch
from edge replace the window. Crazing is defined as a series of small fissures perpendicular to the surface, but not
extending all the way through the pane. There are no surface breaks visible with crazing and it is difficult to see unless the
pane can be viewed from an angle so that light is reflected off the fissure surface. Crazing is usually the result of incorrect
window installation, producing higher than acceptable stress levels, or the application of unapproved fluids.
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Boeing 737-300/400/500 –CFM56-3 ATA 104 - Level 3 B1/B2
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FIGURE 57
Edge Damage
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WINDOW CONCAVITY
Concavity of outer pane is the loss of forming contour causing the pane to move inward. In the event of extreme localized
distortion and thickness variances, check for uneven surface contour and reduced optical quality. Replace
window with concavity of this type. Gentle uniform concavity is not a reason in itself for window replacement. To check for
concavity place a straightedge across narrow width of pane. If a gap exists between the straightedge and the center pane,
the window is concave. Windows prone to fogging are prone to uniform concavity. Check the seals for leakage into window
cavity between outer and middle pane, and check window edges thoroughly for delamination. Replace the window if seals
are known to be leaking.
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Boeing 737-300/400/500 –CFM56-3 ATA 104 - Level 3 B1/B2
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FIGURE 58
Window Concavity
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56-40 INSPECTION AND OBSERVATION
INSPECTION WINDOW
The main gear down lock viewer provides a means for inflight visual inspection of the main gear down lock indicators. The
nose gear down lock viewer permits inflight visual inspection of the nose gear drag link locking components.
The main gear down lock viewer window is located in the floor near the aisle of the main cabin over the wheel well area. The
nose gear viewer window and cover are located in the flight compartment floor above the nose gear wheel well.
MAIN GEAR DOWN LOCK VIEWER
- A plywood cover is taped to the floor panel to protect the viewer window. The viewer consists of the window and two mirrors
mounted in an aluminum alloy viewer tube assembly which is attached to the wing center section pressure web structure.
NOSE GEAR DOWN LOCK VIEWER
- The viewer cover is attached to the floor and is opened to expose the viewer window. The viewer components are aligned
so the field of vision includes the nose gear lock space and the indicator.
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FIGURE 59
Inspection Windows Location
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FIGURE 60
Viewer and Observation Windows
132