Operation of the Landing Gear System
 Figure 011

R 1EFF : 001-049, 101-149, 151-199, 201-299, 1 32-00-00Page 40 1 1 Aug 01/05 1 1 1CES 1 **ON A/C 051-099,

 (Ref. Fig. 011A)
 **ON A/C 301-399,
 (Ref. Fig. 011B)
R **ON A/C 401-499,
R (Ref. Fig. 011C)
 **ON A/C ALL
 A. Main Gear and Doors
 (1) Takeoff
 On takeoff the loads on the MLG decrease. As the aircraft becomes airborne, the shock absorber extends which gives the effect of an increase in the length of the leg. This lets the aircraft move through a large angle during takeoff. When L/G UP is selected the hydraulically operated door opens. Hydraulic pressure at the down lock actuator releases the overcenter lock of the lock stay. The MLG actuator retracts the MLG into the bay. During retraction the BSCU automatically puts the brakes on for a short time. This stops the rotation of the wheels before they go into the bays. The hydraulically operated door closes after the MLG is locked into the bay.
 When L/G DOWN is selected the hydraulically operated door opens. The retraction actuator extends to extend the leg. The side stay and the lock stay move to the over center position to lock the gear in the extended position. The door closes after the gear is extended. With the gear extended the shock absorber absorbs the landing loads.
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 Operation of the Landing Gear System
 Figure 011A 
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 Operation of the Landing Gear System
 Figure 011B 
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R  Operation of the Landing Gear System 
R  Figure 011C 
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 **ON A/C 001-049, 051-061, 101-102, 201-202,

 (2) Nose Landing Gear and Doors
 As the NLG wheels leave the ground on takeoff, the shock absorber extends. The cams in the leg make sure that the wheels are in the center. When the shock absorber is fully extended the BSCU prevents steering outputs to the steering mechanism.
 When the L/G UP is selected the hydraulically operated doors open. Hydraulic pressure at the NLG downlock actuator releases the overcenter lock of the lock stay. The drag strut assembly folds as the NLG retracts. As the leg retracts a rotating joint on the leg cuts off the hydraulic pressure supply to the steering system. As the NLG goes into the bay the wheels touch an anti-spin brake to stop the rotation of the wheels. The hydraulically operated doors close after the gear is locked into the bay.

R **ON A/C 062-099, 103-149, 151-199, 203-299, 301-399, 401-499,
 (2) Nose Landing Gear and Doors
 As the NLG wheels leave the ground on takeoff, the shock absorber extends. The cams in the leg make sure that the wheels are in the center. When the shock absorber is fully extended the BSCU prevents steering outputs to the steering mechanism.
 When the L/G UP is selected the hydraulically operated doors open. Hydraulic pressure at the NLG downlock actuator releases the overcenter lock of the lock stay. The drag strut assembly folds as the NLG retracts. As the leg retracts a rotating joint on the leg cuts off the hydraulic pressure supply to the steering system. The hydraulically operated doors close after the gear is locked into the bay.
 **ON A/C ALL
 (3) Extension and retraction
 (a) Normal Extension and Retraction
 When the L/G control lever is moved the LGCIU sends a control signal to the electro-hydraulic safety valve. The LGCIU controls the sequence of operations to extend and retract the gears and
R 1EFF : ALL 1 32-00-00Page 45 1 1 Aug 01/05 1 1 1CES 1 open and close the doors. The LGCIU uses the position data from the proximity sensors (Ref. 32-61-00) to control the sequence of operations. Only one LGCIU controls the sequence of operations. Control changes from one LGCIU to the other after each retraction/extension cycle.

 (b) Free Fall Extension
 The free fall extension system is controlled by the free fall extension handle in the cockpit. The free fall extension handle is connected to the L/G and door uplocks. When the handle is turned the door uplocks are mechanically opened by the cables. When the doors are open the landing uplocks are also mechanically opened. Gravity then extends the L/G. Springs pull the NLG lock stay and the MLG side stay into the locked position and the L/G doors stay open.
　
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