Undercarriage Systems Flashcards
Shock Struts
Shock-absorbing device
Absorbs by bending and flexing under a load
Oleos
Shock-absorbing device
Consists of a piston acting against compressed air and oil
Air absorbs most of the shocks
Oil prevents excessive movement of the piston and dampens any bouncing action
Torque Link
Fitted to an oleo to prevent turning of its own accord
Allows steering on the ground
Flexes like an elbow joint on the ground and extends in the air
Shimmy Dampers
Prevents lateral vibration which places large stresses on the nosewheel assembly
A small piston-cylinder unit which dampens out oscillations and prevents vibration
Nosewheel Steering
Operated by the rudder pedals
Castoring Steering
Nosewheels which are free to turn but are not connected to controls in the cockpit
Turned using differential braking or the rudder
Retractable Undercarriages
Powered hydraulically
Downlocks
Lock the landing gear down
Mechanical latch
Uplocks
Mechanical latches which lock the wheels up when retracted
Allows the electric or hydraulic system to shut down
Anti-Retraction Devices
Squat switch, commonly attached to the torque link
Prevents the gear from retracting when the weight is on the wheels
Warning Devices
Green light: landing gear extended
Warning horn or light: Alerts pilot when power is reduced below a certain setting when the gear is not down
Emergency Extension
Manual
Free-fall: a lever to unlock the uplocks and the gear falls under its own weight
Hand pump: for heavier landing gear with its own reservoir and selector valve
Emergency air bottle: blow the landing gear down pneumatically
Speed Limitations for Retracatable Undercarriages
A maximum allowable airspeed when the landing gear is extended (VLE)
A maximum speed at which the gear may be operated (VLO)
