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ATR 42-500 > Landing Gear > Flashcards

Flashcards in Landing Gear Deck (13)
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Gear Position Detection and Indication System

Consists of two independent systems. The primary is managed by MFC module 1A and position is displayed on the main instrument panel. The secondary is managed by MFC 2A and displays position on the overhead panel. The gear must be considered in agreement with handle position if at least one system indicates agreement (3 green or no red UNLK).


Gear Doors and Uplocks

Uplocks are mechanical and unlocks are achieved hydraulically. Main gear doors are linked to the gear. Nose gear has four doors actuated by the gear mechanically. The forward doors close with gear up or down; aft doors remain open when gear is extended.


Landing Gear

Electrically activated and hydraulically operated by the green system. The main gear wheels are automatically braked when the handle is selected up. Hydraulic pressure is released from the line when the gear reaches its selected position. Each main gear assembly has an oleo-pneumatic shock absorber and is fitted with two wheels each equipped with anti-skid brakes. The nose wheel is two wheeled and equipped with an oleo-pneumatic strut and a steering system.


LDG GEAR Unsafe Indication

The CCAS is activated and may not be silenced when any gear is not seen down and locked with flaps 35 and less than 500ft ZRA. The CCAS is also activated, but may be silenced when any gear is not seen down and locked with at least one PL at FI and less than 500ft ZRA.


Landing with Abnormal Gear

It is preferable to land with all available gear down and locked as opposed to belly landing. And take advantage of runway foam.


Emergency Gear Extension

The landing gear may be extended mechanically in the event of hydraulic or electrical failure by a push pull handle at the rear of the pedestal. When the handle is pulled above the pedestal, gravity and aerodynamic forces extend the gear. Main gear is assisted by a gas actuator and the nose gear is assisted mechanically.


Nose Wheel Steering

Steering is provided by a servomechanism mechanically controlled from the CAPT tiller wheel and powered by the blue hydraulic system. Under power, the nose wheel turns +/-60* and +/-91* with the system deactivated. With the gear not down and locked, a swivel valve shuts off blue pressure. And a WOW solenoid inhibits steering when the main and nose shock absorbers are not compressed. Differential braking and thrust may be used to guide the aircraft in the event of steering failure.


Wheel Brakes

The four main gear wheels are equipped with multi-disc brakes equipped with an automatic adjuster, a wear indicator and an overheat detector. Two modes are available normal and emergency/parking. Normal braking is controlled by the pilot's toe pedals, equipped with anti-skid and green hydraulic pressure supplies the system . Emergency/parking brake is operated by the brake lever on the pedestal, has no anti-skid and is supplied by the blue system.


Main Gear Fusible Plugs

Main gear wheels are equipped with fusible plugs designed to release internal pressure when wheel temperature exceeds 177*C in Oder to prevent tire and wheel bursting.


Emergency/Parking Brake

EMER notch gives a metered pressure to the brakes without anti-skid
PARKING notch gives full pressure to the brakes.
In the event of hydraulic failure, the accumulator allows at least six applications of brakes.
When the brake handle is not fully released, the PRKG BRK caution light illuminates on the CAP and is taken into account by the T/O CONFIG warning system.


BRAKE and HYD PRESS Indicators

Blue and Green system pressures are displayed with EMER/PKG accumulator pressure. All are normal at 3000psi


Anti-Skid System

Operative when speed is >10kts.

Activates when speed is >23kts +50% differential between wheels (locked wheel protection)

Braking is inhibited during wheel spin up to 35kts or for 5s (touch down protection)

Testing of the system should not be performed with engines on and brake released, test is inhibited with wheel speed >17kts.


Hot Brake Indicator

Alert light and CCAS are activated when any brake temperature is sensed above 160*C.