Landing Gear

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General

The G200 has 4 main landing gear tires and two nose landing gear tires.

The landing gear is tricycle type with two wheels on each gear strut. Each unit retracts into its? own well and is fully covered by doors, mechanically connected to the landing gear.

Landing gear extension and retraction time is 9 ? 1 seconds. In emergency, landing gear may be extended by compressed nitrogen.

 

Main Landing Gear

Each main landing gear wheels are mounted on a trailing beam pivoted on the main landing gear strut. Its shock absorber is pin-connected at both ends, absorbing the beam energy and transmitting the ground loads to the upper portion of the main landing gear structure.

The ground loads are reacted by the wing structure by the journal bearings mounted coaxially in the wing, cordwise direction, and by the bracing actuator attached to the main landing gear strut.

The main landing gear retracts inwards into the fuselage wheel well. Each main landing gear has two doors. The outboard door is rigidly attached at the strut. The inboard door operates by mechanical linkage to the strut and is held in up position by two uplock cylinders. This uplock is released when landing gear lever is placed in down position by hydraulic pressure, or by nitrogen pressure in emergency. The main landing gear is held, while airborne, in retracted position by hydraulic pressure in the actuator and by the inboard door mechanical uplock if pressure drops.

As the gear is extended, an internal lock in the actuator automatically locks it in fully extended positions.

The main landing gear actuator also serves as the gear brace. The downlock is released when landing gear lever is placed in UP position by hydraulic pressure.

Nose Landing Gear

The nose landing gear strut is cantilevered, sliding telescopically in a rotating tube. The rotating tube is positioned by a rack and pinion steering system. The steering movement is transmitted to the wheel axle by torque links. The steering angle is ? 60?, permitting runway width of 15 meters. Towing angle is ? 100? without disconnecting the torque links. A towing adapter is mounted on the strut with an integral safety shear pin.

Ground loads are applied to the fuselage structure by means of two bearings and a drag brace. The drag brace is locked automatically in fully extended position by jury brace; it is unlocked by a hydraulic unlock actuator.

The nose landing gear retracts forwards and locks up by spring-loaded mechanical lock. It is unlocked by hydraulic pressure. The hydraulic retracting actuator is sized to retract and extend the landing gear and doors. When the nosewheel is off the ground, the nose landing gear is centered by internal cams in the sliding tube, while the hydraulic supply is cut off from the steering system.

The nose landing gear bay three doors are actuated mechanically by a system of bellcranks and rods connected to the levers on the nose landing gear strut trunnion. The two side doors open and close during nose landing gear extension and the rear door is opened backwards and remains open while the nose landing gearis down.

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Emergency Gear Extension

Emergency extension of the landing gear requires actuating the emergency gear DOWN handle (on left side of the pedestal), releasing compressed nitrogen to drive the landing gear into down & locked position, and opening a valve to direct the upward hydraulic pressure to the return line; this enables landing gear extension even if landing gear lever is stuck in UP position.

Once the gear Emergency DOWN handle is pulled, landing gear must not be retracted again.

Landing Gear System Controls and Indicators

Landing gear lever - Located on landing gear control panel on the front pedestal. It retracts and extends landing gear. Two positions: UP and DOWN

Downlock Override button - Energizes solenoid of downlock plunger if ground contact switch fails

Warning Messages:

GEAR NOT DOWN - Landing gear is not down and locked with radar altitude less than 800 ft (400 ft with MOD 7222) and one thrust lever at or below max cruise detent or flaps position more than 25 degree

Wheel and Brakes

Normal and emergency hydraulic wheel brake systems are controlled by conventional, dual, ?tip-toe? brake pedals which actuate multi-disk self-adjusting brake units on each of the four main landing gear wheels. Normal operation of the brakes on each main landing gear strut is controlled by an anti-skid valve.

 

A. Normal Operation

The normal and emergency wheel brake systems are controlled by mechanical inputs from brake pedals, with the pilots and co-pilots commands mechanically interconnected. When the pedals are pressed, proportional pressure from the right hydraulic system is metered by the power brake valve to the anti-skid control valves, and then through fuse and shuttle valves, into two split brakes on each main wheel, separately. Under normal operation, hydraulic pressure is directed to the brakes; pressure to the brakes is governed by pilots metered pressure and modulated by anti-skid to minimize wheel skid.

If any of the brake lines leading to the inboard wheels is broken, the hydraulic fuse on that side prevents loss of excessive amount of fluid and shuts off flow to the affected brake. The residual braking effect is 3/4 of normal.

B. Emergency Operation

Emergency braking is used when the right hydraulic system fails. To obtain emergency braking, the PARK/EMERG lever is placed in EMERG position. The left hydraulic system pressure is used with half of the normal braking capacity. If both hydraulic systems fail, accumulator pressure is sufficient for six applications of emergency brakes for a total of 50 seconds (or one T/R deployment). Anti-skid system is inoperative.

C. Parking

Parking is obtained when the PARK/EMERG lever is placed in PARK position. The lever closes a switch that energizes the parking valve and connects the right hydraulic system pressure and the right T/R accumulator pressure to the normal brake lines through shuttle valves.

D. Anti Rotation

The anti rotation function stops main wheels rotation after take-off during landing gear retraction before the main landing gear enters the wheel wells.

Back-pressure, developed in the return line during landing gear retraction, is directed into the power brake valve through the return port, which directs pressure through the (inoperative) anti-skid valve into the brakes (the anti-skid disengages when the landing gear goes out of down and locked position).

 

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