LANDING GEAR AND BRAKES (ASM) Flashcards
How many weight on wheel sensors are there
5
What processes the gear proximity switches
Landing Gear Electronic Unit (LGEU)
How many signals are processed for an adequate reading
4 signals are processed to ensure 3 are identical
What does the nose gear switch send signal to
Thrust lever
Steering
Gust lock
Landing gear downlock
Positioning the gear lever up does what
Sends signal to LGEU to close nose gear solenoid and main gear electrovalve
Positioning the gear lever down does what
Sends signal to LGEU to open electrovalve and solenoid reaching the actuators and uplocks
Purpose of the Electrical Override Extension
Bypass the LGEU actuating the Solenoid and Electrovalve
Purpose of the Free Fall Extension
Backup for Normal and Electrical Override
What happens when the gear is released with free fall
Unlocks Uplocks
Isolates hydraulic system pressure
Gravity causes gear to fall
When does the landing gear warning sound
RA Below 1200
Flaps lower than 22º
Thrust levers below 59º
What hydraulic system provides normal braking
System 1 and 2
What system provides emergency braking
System 2
What controls and monitors normal braking
The BCU
Where do BCV 1 and 4 control pressure
Hydraulic System 1
What brakes do BCV 1 and 4 control
Outboard wheels
Where do BCV 2 and 3 control pressure
Hydraulic System 2
What brakes do BCV 2 and 3 control
Inboard wheels
Purpose of Anti-Skid Protection
Controls amount of hydraulic pressure to brake
BCU monitors wheel velocity to control skidding
When is locked wheel protection activated
Wheel speeds above 30 knots
When is Anti-Skid Protection deactivated
Wheel speeds below 10 knots
How does locked wheel protection work
if one wheel speed is 30% or lower, pressure is releaved
When is locked wheel protection deactivated
Below 30 knots
Purpose of touchdown protection
Inhibits brake actuation before main wheel spin up
When does touchdown protection occur
3 seconds after touchdown or main wheel speed 50 knots
How is nose wheel steering controlled
Electronically controlled, hydraulically operated