CHAPTER 14

LANDING GEAR

Page

TABLE OF CONTENTS 14-00-01/02

DESCRIPTION

General 14-10-01

Description 14-10-01

Controls and Indicators 14-10-04

COMPONENTS

Nose Gear 14-20-01

Main and Center Gear 14-20-02

CONTROLS AND INDICATORS 14-30-01

FUNCTIONAL SCHEMATICS

Main Wheel Brakes and Anti-Skid System 14-40-01/02

Automatic Brake System 14-40-05/06

JL Nov 1/79 14-00-01/02 GEAR

GENERAL jammed in the up position, the main and nose gear can be mechanically unlatched The has a tricycle by an alternate gear extension lever comprised of four-wheel trucks on each in the floor at the right side of the pedes- main gear, and dual wheels on the nose tal, and the center gear, if installed, gear. A supplemental dual-wheel center can be unlatched by a center gear alter- gear is installed on the international ver- nate extension handle on the floor, just sion only. Domestic version aircraft forward of the lower main circuit breaker have provisions only for installation of panel. This allows all gear to free-fall the supplemental dual-wheel center gear. and mechanically latch in the down posi- The landing gear and main gear wheel- tion. The main landing gear is normally well doors are hydraulically actuated. held in the up position by hydraulic The main and nose gear can be pressure. In the event of loss of pres- extended without extending the center sure, the main gear rests on the main gear on aircraft that have the center gear wheelwell doors, and the nose gear and installed. A free-fall capability is center gear are held up by overcenter designed into the system for use if linkage. required by hydraulic failure. An electrically monitored, visual/aural Trim cylinders maintain the truck beams indicating and warning system provides perpendicular to the main gear . indication of gear status during various On aircraft with Service Bulletin 32-135 phases of flight. Dual, hydraulic incorporated or production equivalent, a powered, multi-disk wheel brakes with trim cylinder interlock mechanism pre- anti-skid control systems are provided vents moving the gear handle to up in on the main and center gear. Accumu- the event of hydraulic failure in the trim lators in the system provide reserve system. brake pressure in the event of normal hydraulic system pressure loss. NOSE GEAR STEERING SYSTEM DESCRIPTION Nose gear steering is powered by hy- LANDING GEAR SYSTEM draulic systems 1 and 3. Both the nose gear steering wheel and the The landing gear and main gear doors pedals provide steering control. The are retracted and extended by hydraulic nose gear steering wheel has override system 3. If system 3 has a loss of authority over rudder pedal steering. pressure, but fluid is available, hydraulic The nose gear steering wheel pro- power to retract the gear can be supplied vides steering up to 68 degrees on if either the (1-3) or (2-3) reversible either side of neutral, and full rudder motor-pumps are operating. pedal travel provides steering up to a maximum of 10 degrees on either side If no hydraulic pressure is available due of the neutral position. If hydraulic to loss of fluid or complete system fail- system 1 or 3 fails completely, nose- ure, or if the landing gear lever is wheel steering is limited to 25 degrees

JL Nov 1/81 14-10-01 in the direction of the inoperative hydrau- when the gear is not down the flaps are lic system. Rudder pedal steering is extended beyond the approach flaps not noticeably affected by loss of one position. hydraulic system. Rudder pedal steer- ing is rendered inoperative by the In the event the electrical indicator sys- mechanical ground sensing mechanism tem malfunctions, it is possible to con- during nose gear extension at firm that the landing gear is down and takeoff. Nose gear steering using the locked by observing mechanical indica- nose gear steering wheel while the gear tors. Determination that the main gear is retracted is not possible as the is down and locked can be made by steering bypass valve is mechanically observing a button protruding from the placed in a bypass mode upon nose gear top surface of each wing. A viewing retraction. This prevents inadvertent window in the cabin floor and through a steering and possible jamming of the main gear wells is also provided for nose wheels in the wheelwell while checking that gear is up and doors are retracted. closed. Viewing tubes installed in the floor of the forward cabin provide means GROUND SENSING SYSTEM of visually checking the nose gear locks. No provisions are made for visual check A mechanically operated ground sensing of the center gear locks, however uplock- mechanism is provided on the aircraft. ing may be verified by means of the It is operated by extension and compres- center gear alternate extension handle sion of the nose gear strut. The sys- on aircraft with the center gear installed. tem mechanically disables rudder pedal On aircraft with or without the center nosewheel steering, operates the gear gear installed, center gear door locking handle antiretraction release mechanism, closed may be verified by means of the and cams two switches which energize or center gear alternate extension handle. deenergize a number of ground control relays which establish a ground or flight BRAKE SYSTEM mode of operation for various systems. There are two independent braking sys- VISUAL/AURAL INDICATING AND tems for each of the eight main wheels WARNING SYSTEM and two center wheels when installed. Each brake system uses a separate hy- The landing gear position indicating sys- draulic power system. Brake system 1 tem consists of lights, aural warning, utilizes power from hydraulic system 1, and mechanical indicating elements. and provides pressure to brakes on all Red and green lights are provided to main and center gear wheels. Brake give visual indication of the status of system 2 is powered by hydraulic sys- the landing gear in relation to landing tem 3 and provides pressure to brakes gear handle, alternate gear extension on all main gear and center gear wheels lever, and position for all independently of brake system 1. Ade- phases of flight. Below 215 KIAS, an quate braking for all landing conditions aural warning horn and red lights will is available with only one brake system annunciate a configuration in which the operative. Each brake system is pro- gear is not down and any is vided with two accumulators which will retarded. Above 215 KIAS only the lights supply reserve braking pressure in the warn of this condition. At any speed, the event of normal hydraulic pressure horn sounds if the flaps are extended failure. Fully charged accumulators will beyond the approach position with the provide approximately 6 normal manual gear not down. The horn can be silenced power brake applications. Brakes are by use of a gear horn off button, except available as long as brake system

JL 14-10-02 Aug 1/81 pressure is above the red band on the one on the pedestal and one on the respective brake system hydraulic overhead panel indicate when the pressure gage. Pedal forces required parking brake handle is set to park to actuate brakes are very low, and position. The takeoff warning aural the brake pedals can actually be signal (intermittent car horn sound, bottomed even though the system is identical to cabin altitude warning) functioning normally. sounds when the ground shift mechan- ism is in the ground mode and either throttle 1 or 2 is advanced for On some aircraft, brake temperatures takeoff and the parking brake is not are monitored by OVHT lights and a released. BRAKE TEMP gage that will selectively display the temperature of any brake. AUTOMATIC BRAKE SYSTEM (ABS) Normally the brake temperature gage (Installed on some aircraft) indicates the temperature of the hottest brake. If the wheel is ex- The automatic brake system (ABS) pro- posed to excessive brake temperature, vides the means for automatically fuse plugs in the wheel will melt applying the brakes during the land- causing tire pressure release. ing mode. The system consists of a control panel, indicating lights, an auto brake control unit, and a land manifold. The parking brakes are set by apply- ing full braking pressure with the In the landing mode, ABS operates toe operated rudder pedal brakes, only from brake system 1 (hydraulic positioning the park brake handle system 1) and provides selection of fully aft, and then releasing the one of three modes of operation; rudder pedals. This action traps minimum, medium or maximum. In min- braking pressure in the system. imum and medium modes of operation Adequate parking brake pressure is the system compares actual aircraft available if the brake system hy- deceleration, (from flight guidance draulic pressure gages indicate in system linear accelerometer) with the white band. With parking brake the mode selected and maintains a set for several hours, normal hyd- constant level of deceleration. In raulic system bleed off can result the maximum mode, full brake system 1 in no pressure at brakes. As long pressure is applied to the brakes as brake pressure is indicated there (limited only by anti-skid system will be pressure at the brakes. The operation) and maximum deceleration parking brakes may be released by is achieved. Landing mode is armed fully depressing, then releasing the after gear is down prior to landing toe pedals. If hydraulic system(s) by selecting the deceleration level depressurize(s) while parking brakes desired and arming the system. are set, the brake pressure later Arming of the ABS requires the ABS bleeds off, then parking brakes will being operative, (no system failure), be repressurized automatically when deceleration level selected prior to hydraulic system(s) are repressurized, landing anti-skid armed and oper- and this will occur without resetting ational and the linear accelerometer parking brake handle. Two lights, unit-2 operative.

JL Feb 1/87 14-10-03 The ABS landing mode is activated when trolled by individual wheel speed spoilers are deployed (either auto- transducers, anti-skid control box, matically or manually) with throttle and individual anti-skid control levers retarded and brake pedals re- valves for each main and center wheel leased. Automatic braking is delayed brake. Pilot induced manual brake after deployment for approx- valve pressure (as a result of toe- imately 1 second in maximum mode and brake pedal deflection) is metered as approximately 3 seconds in mimimum or necessary to provide efficient braking medium modes to allow for normal nose and prevent tire skidding. The anti- wheel touchdown. Pilot takeover can skid system responds most efficiently be initiated at any time and ABS sys- with full pedal application (pedals tem will disarm if brake pedal is bottomed) or at least steady partial depressed beyond approximately 40 per- pedal application. The system incorp- cent of travel, if throttle lever 1 orates locked wheel touchdown protect- or 3 is advanced beyond 15 degrees, ion, to the rear bogie wheels only, to deceleration selector is moved to prevent inadvertent landing with the OFF position. The arm-disarm switch brakes applied. A shift from ground will move to DISARM and ABS lights mode to flight mode, while on the will cone on for the above conditions. ground, will release the rear bogie (Moving AUTO BRAKE deceleration sel- wheels at low speed leaving normal ector to OFF will not turn on ABS braking on forward bogie wheels. The lights). Stowing ground spoilers will system automatically reverts to a release brake pressure without disarm- manual power brake system, below 10 ing the ABS landing mode. The ABS knots for the main gear and on some lights will remain off and automatic aircraft 3 to 4 knots for the center- braking will again be available if line gear, but the anti-skid lights spoilers are re-deployed. remain off. An arming switch, test button, and indicating lights are An ABS malfunction will cause the provided to control and monitor the system to automatically disarm. The system. arm-disarm switch will move to DISARM, and indicating lights will come on. To rearm the ABS system after it has CONTROLS AND INDICATORS automatically disarmed, the deceler- ation selector must be moved to OFF Controls, indicators, and annunciator and then back to the deceleration lights are on the pilots' instrument setting and the arm-disarm switch panels, Pedestal, Overhead Panel, and moved to ARM. If the fault has Flight Engineer's Upper Instrument cleared, the system will rearm. In Panel No. 3. The main and nose gear flight the ABS is disarmed when the alternate gear extension lever is to gear handle interlock relay senses the right of the pedestal on the floor the gear handle up. and the center gear alternate exten- sion handle is on the floor forward of ANTI-SKID SYSTEM the main circuit breaker panels. Illustrations of these major panels A fully automatic, pressure modulating are in Chapter 1. Individual controls anti-skid control system is installed and indicators are illustrated and in each of the two hydraulic power described in another section of this brake systems, the system is con- chapter.

JL 14-10-04 Feb 1/87 NOSE GEAR DOWN LOCK SAFETY PIN LOCKPIN INSTALLED WITH HANDLE IN BYPASS POSITION

BYPASS VALVE LOCKPIN

NORMALLY CLOSED

PARKING BRAKE LINKAGE INDICATOR (ENGAGED)

BYPASS VALVE AND LANDING GEAR DOWNLOCK PIN

JL May 1/76 14-20-01 MAIN AND CENTER GEAR MAIN GEAR DOWN LOCK SAFETY PIN

MAIN DOOR HANDLE

LEFT GEAR SHOWN RIGHT GEAR OPPOSITE

CENTER GEAR (If Installed) DOWN LOCK SAFETY PIN

STRUT PRESSURE GAGE

JL 14-20-02 May 1/76 LANDING GEAR - Controls and Indicators GEAR Handle GEAR Lights (Nose, Left, Right & Center) (Copilots Instrument Panel & F/E's Upper Mechanically positions landing gear hydraulic Instrument Panel No 3 An unsafe indication control valve for retraction or extension of Ian on one of two gear indicating systems does ding gear To move handle from UP or DOWN, not require a mandatory visual inspection) it must be pulled aft GREEN - Come on when gear handle is down An interlock prevents moving gear handle to and landing gear is down and UP, if hydraulic pressure to landing gear trim locked Also on when gear handle is system fails up and landing gear is down and locked, if alternate gear extension GEAR HANDLE REL Button lever is raised Releases anti-retraction mechanism and per- RED - Come on when landing gear is not mits gear handle to be placed in UP in event of down and locked and handle is down an anti retraction release mechanism malfunc or when any unsafe condition exists Also comes on when landing gear is tion in transit or not in agreement with gear handle, or when gear is up and GEAR LT TEST Button locked and any throttle is retarded When pushed, red lights for nose, left, center to idle and right gear will come on OFF - When gear handle is up and gear is up and locked CTR GEAR Isolation Switch NOTE Permits mam gear to be extended without Both red and green lights for respective mam extending center gear gear will be on when mam gear door maintenance safety hook is installed UP - Prevents center gear from being extended when mam gear is extended Center gear warning cir cuits are inhibited NORM - Center gear will be extended and retracted when mam gear is extended and retracted by means of GEAR handle NOTE SEE NOTE 1 1 On domestic configuration NORM placard is covered to obscure 2 On domestic configuration center gear SEE NOTE 2 switch is guarded in UP by an additional (COPILOT'S guard placarded INSTRUMENT PANEL) GEAR HORN OFF Button When pushed, will silence gear warning horn Alternate Gear Extension Lever when flaps are not in landing range Lifting Lever — Mechanically releases all uplatches ex cept center gear Lever Release Pushrod Knob — Mechanically positions landing gear To unlock alternate gear extension lever to control valve to bypass and shuts off return to stowed position lift lever to relieve hydraulic system 3 pressure to nose tension on link in detent, then press down on gear steering pushrod knob on outboard side of lever and - Limits nose gear steering in this case to allow lever to return to stowed position (PEDESTAL) 25 degrees to right (pressure from hydraulic system 1) when using nose gear steering wheel - Unlocks outboard if they are locked Stowing Lever If hydraulic system 3 is operative - Retracts gear if gear handle is at GEAR UP - Returns nose gear steering to normal Placarding on (hydraulic system 3 is restored) outside of door CAUTION ALTERNATE LANDING GEAR EXTENSION Lever is preloaded when in up position when ALTERNATE OUTBOARD UNLOCK flaps are not extended Restrain lever when PULL UP FORCIBLY FULL STROKE stowing RIGHT SIDE OF PEDESTAL ON FLOOR Center gear is installed on the international configuration only. Domestic configuration aircraft have provisions only for center JL gear. Aug 1/81 14-30-01 LANDING GEAR - Controls and Indicators

Nose Gear Steering Wheel Provides nosewheel steering up to 68 degrees left and right of the neutral position and overrides the rudder pedal steering. Full rudder pedal movement results in up to 10 degrees steering on either side of the neutral position as long as the ground shift mechanism is in the ground mode.

(CAPTAIN'S CONSOLE)

Placard added on domestic configuration airplanes.

COVER PLATE

Center Gear Alternate Extension Handle Pulling handle up will mechanically unlatch center gear and allow it to free fall and lock in down position, providing Alternate Gear Extension Lever has been raised to position landing gear control valve to a bypass position. Handle is also used to determine that center gear is locked in retracted position

FORWARD OF MAIN CIRCUIT BREAKER PANELS ON FLOOR

Center gear is installed on the international configuration only. Domestic configuration aircraft have provisions only for center gear. JL 14-30-02 Feb 1/86 LANDING GEAR - Controls and Indicators

Brake OVHT Switch-Lights (10) BRAKE TEMP Gage Lights come on to indicate Displays the temperature of the overheat condition in the respec- hottest brake or any other brake tive brake BRAKE OVHT light as selected by pushing the (pilot's overhead panel) also com respective OVHT switch light es on Pushing the switch-lights will select the respective brake to dis- play the temperature on the BRAKE TEMP Gage Pushing two or more switch-lights simultaneously will give erroneous brake temperature readings Brake Temp TEST Button DIFF TEMP Light When pushed, the Brake OVHT The amber DIFFerential switch-lights and the DIFF TEMP TEMPerature light comes on light come on and the brake when the temperature of any temperature gage pointer will be brake is excessively above or within the white band to indicate below the average brake that temperature indicating cir temperature cuits are functional (FLIGHT ENGINEER'S UPPER PANEL NO 3)

BRAKE Sys HYD PRESS Gage (1, 2) Provide visual indication of hydraulic pressure in the respective brake system SYS 1 — Gage displays hydraulic pressure in brake system 1 The pressure shown at any given time will be the highest of the following 1 Hydraulic system 1 2 Brake system 1 accumulator

SYS 2 — Gage displays hydraulic pressure in brake system 2 The pressure shown at any given time will be the highest of the following 1 Hydraulic system 3 2 Brake system 2 accumulator

Brake temperature control panel is installed on some aircraft. Center gear is installed on the international configuration only. JL Domestic configuration aircraft have provisions only for Aug 1/80 center gear 14 - 30 - 03 LANDING GEAR - Controls and Indicators

PARK BRAKE Handle PARK Brake Light When brakes are fully applied for Comes on when parking brake handle parking, braking is maintained by is set to park position and will go off positioning handle aft. Trapped fluid when parking brake is released and accumulator pressure then main- tain parking brake pressure.

(PEDESTAL)

PARK BRAKE ON Light Comes on when parking brake handle is set to park position and will go off when parking brake is released.

ANTI-SKID FAIL Light (5) BRAKE OVHT Light All anti-skid fail lights will come on if a failure occurs that affects total system Master brake overheat light comes on operation This includes loss of all ac to indicate overheat condition of any power to anti-skid box, failure of park brakes. BRAKE OVHT switch-lights brake valve to open, anti-skid switch is (F/E's upper panel No. 3) also come on. in OFF, or a switch on front of anti-skid Brake overheat light is operable on control box is in wrong position A single some aircraft. anti-skid fail light will come on when system self test has detected a failure in an associated wheel circuit ANTI-SKID TEST Button Anti-skid switch must be in ARM for test button to be functional Pushing test button should cause all ANTI-SKID Switch anti-skid fail lights to illuminate, then OFF - De-activates anti-skid system extinguish If an individual light fails and restores full braking con- either to illuminate or extinguish, a trol to pilots' toe-pedal failure has been detected in one or both operated manual power brake wheel circuits associated with that light valves Turns on ANTI-SKID NOTE FAIL lights. ARM - Permits anti-skid system to Anti-skid test system will operate with meter any excessive pilot in- parking brakes on or off, and at taxi duced hydraulic braking speeds less than 30 knots pressure as required to pre- vent locking wheels or skid- ding tires. OVERHEAD PANEL

Center gear is installed on international version only. Domestic version aircraft have provisions only for center gear. JL 14-30-04 Nov 1/81 LANDING GEAR - Controls and Indicators

AUTO BRAKE Light Comes on to indicate ABS malfunc- tion.

(OVERHEAD PANEL)

NOTE: AUTO BRAKE SYSTEM IN- OPERATIVE IN THE DELIVERED CONFIGURATION, LIGHTS WILL COME ON WHEN ANNUNCIATOR TEST IS USED.

ABS Light Comes on anytime ABS is automatically disarmed or pilot elects to take over braking action.

GLARESHIELD

Effective for airplanes with lights only installed.

JL Nov 1/79 14-30-04A LANDING GEAR - Controls and Indicators

AUTO BRAKE Deceleration Selector OFF - ABS inoperative Pilot braking only available TO - INOPERATIVE AUTO BRAKE ARM - DISARM Switch LAND - Selects deceleration level for ARM - ABS armed for automatic ABS landing mode Provides braking upon spoiler de- selection of one of three de- ployment during landing celeration levels when spoil- mode Switch magnetically ers deployed either held in ARM automatically or manually during landing with ABS DISARM - ABS inoperative Pilot brak- armed Brake pressure avail- ing only available able from brake system 1 only

AUTO BRAKE Light Comes on to indicate ABS malfunction System will automatically disarm and AUTO BRAKE ARM-DISARM switch will move to DISARM MASTER CAU- TION light also comes on OVERHEAD PANEL

ABS Light Comes on any time ABS is automatical- ly disarmed as a result of system mal- function or pilot elects to takeover braking action by depressing brake ped- als beyond 40% travel, advancing throt- tles 1 or 3 beyond + 15 degrees or placing AUTO BRAKE ARM-DISARM switch to DISARM while AUTO BRAKE deceleration selector is in any LAND position Light will not be on when AUTO BRAKE GLARESHIELD deceleration selector is in OFF

Effective for aircraft with lights and control panel installed JL Feb 1/87 14-30-04B LANDING GEAR - Controls and Indicators Landing Gear Combination Tire Pressure Gage/Fill Valve

TIRE PRESSURE GAGE/FILL VALVE

Effective on some aircraft.

JL Aug 1/81 14-30-04C/04D LANDING GEAR - Controls and Indicators Main Landing Gear Visual Downlock Indicator

LINE OF SIGHT TO MAIN GEAR VISUAL INDICATOR DOOR UPLOCK Indicator button is raised when THRU VIEWING the gear is in down and locked WINDOW position TOP SURFACE OF WING

MAIN GEAR DOOR UPLOCK

VIEW LOOKING AFT AT LEFT MAIN LANDING GEAR, RIGHT SIDE IS OPPOSITE

JL Aug 1/81 14-30-05 LANDING GEAR - Controls & Indicators Left Main Landing Gear Door Uplock Shown, Right Side Is Opposite CARPET PULLED When lying flat in place, this BACK edge lies against seat track

LINE OF SIGHT Located in line with the sixth cabin window aft of the cabin left and right overwmg doors

MAIN LANDING GEAR WHEELWELL LEATHER LOOP ACCESS PASSENGER DOOR COMPARTMENT GEAR WELL FLOOR LIGHT SWITCH FASTENER VIEWING WINDOW Red stud and stripe must be aligned to indicate door ALTERNATE GEAR closed and latched RELEASE CABLE

GEAR WELL OUTBOARD EDGE

DOOR UPLOCK HOOK RED DOOR STRIPE OUTBOARD EDGE RED STUD RED STUD

RED STRIPE

DOOR CLOSED AND LATCHED

DOOR PARTIALLY OPEN

14-30-06 JL May 1/79 LANDING GEAR - Controls and Indicators Nose Gear Visual Uplock and Downlock Indicator

Viewing Tubes In line with forward edge of fourth window aft of forward cabin doors and to left of center seat tracks.

TRANSPARENT VIEWING CAPS (REMOVABLE) SEAT TRACK

NOSE GEAR LOCK VIEWING INSTRUCTIONS 1. REMOVE COVER PLATE 2. EYE POSITION SHOULD BE APPROX 15 INCHES ABOVE FLOOR

INDICATOR "A" MUST UPLOCK BE IN LINE WITH GEAR WELL INDICATOR "B" AS SHOWN DOWNLOCK LIGHT SWITCH FOR LOCKED GEAR

Access Door Roll back carpet and lift access door for access to viewing tubes.

Visual Indicator RED surfaces must be in alignment for both gear down and locked and gear up and locked positions. UPPER OVERCENTER LINK

LOWER OVERCENTER LINK

JL Aug 1/81 14-30-07/08 MAIN WHEEL BRAKES AND ANTI-SKID SYSTEM Ground Mode

International Configuration Auto Brake Takeoff Manifold installed on aircraft JL with Service Bulletin (32-152) incorporated. Feb 1/82 14-40-01/02 MAIN WHEEL BRAKES AND ANTI-SKID SYSTEM Ground Mode

Domestic Configuration Auto Brake Takeoff Manifold installed on aircraft JL with Service Bulletin (32-152) incorporated. Feb 1/82 14-40-03/04 AUTOMATIC BRAKE SYSTEM

Effective on aircraft with Auto Brake System installed. Center gear is installed on the international configuration only. JL Domestic configuration aircraft have provisions only for center Aug 1/81 gear. 14-40-05/06