Landing Gear and Brake System Flashcards
(B) How is the landing gear extended and retracted?
Electrically commanded and hydraulically actuated
(B) When will the aural warning for the landing gear sound?
If the gear is not down and locked:
- Less than 700’ RA and TLA below 45°
- SLAT/FLAP 5 or full regardless of altitude
- TLA below 59° for one-engine inop
(B) Can the landing gear aural warning be silenced by pushing the ‘LG WRN INHIB’ button?
Yes, only if both radio altimeters fail
(B) What are three landing gear extension modes?
- Normal: The landing gear level DOWN
- Electric Override: Bypasses PSEM to directly command selector valve
- Alternate Gear Extension: Manual uplock release opens free-fall sequencing valve
(B) What is the purpose of the DN LOCK RLS button on the landing gear?
- Mechanically releases the landing gear lever lock
- Lock protects against inadvertent landing gear retraction when weight-on-wheels
(This is a locking solenoid)
(B) What keeps the gear locked in position?
- Extended Downlock Springs
- Retracted Uplock hooks
(B) Describe the landing gear indications?
- GREEN: Down and Locked
- White: UP and Locked
- Amber: In Transit
- Red: Gear position and lever disagreement (20 sec grace period)
(B) How do the landing gear doors actuate?
Mechanically, during landing gear extension or retraction
(B) What is PSEM?
Proximity Sensor Electronic Module
(I) What does PSEM do for the landing gear?
It monitors the WOW sensors to determine if the airplane is on the ground or in-flight
It controls the extension and retraction of the landing gear
(also indicates position of landing gear, spoiler and aircraft doors)
(I) What is WOW?
Weight-on-Wheels
(T) How many WOW sensors and where are they located?
Total of six
2 installed on each landing gear
(T) What controls the Nose Steering lights?
NWSCM - Nose Wheel Control Module
(O) How is the the nose-wheel powered in order to move?
Hydraulic Steering Motor
(T) What keeps the Nose Wheel Down?
Folding Drag Brace and this is supported by a locking stay/pair of down-lock springs
(T) How many doors in the nose-wheel section?
2 pair of doors - Front Doors must remain closed on ground
(T) How many actuators per landing gear?
2 - Hydraulic Retraction Actuator and Hydraulic Actuator for the locking stay
(B) How are the brakes commanded?
- Brake by Wire (B-FBW)
- Electronically commanded and hydraulically actuated
- Pedal position transducers send brake requests to the BCM (Brake Control Module)
(B) What hydraulic systems provide brake pressure?
HYD SYS 1 - Outboard Brakes
HYD SYS 2 - Inboard Brakes
HYD SYS 1 and 2 - Emergency Brakes/Parking Brake
(B) What protections are provided for braking?
- Touch-down: No Braking until 3 seconds or > 50 knots wheels speed after touchdown
- Anti-Skid: Compares wheel speeds and releases pressure (inoperative below 10 knots)
- Locked-Wheel: Allows up to 33% differential braking for steering purposes (inoperative below 30 knots)
(B) How many applications will the parking/emergency brake provide?
Six fuell brake applications
(B) What stops the wheels from spinning during retraction?
Main Gear - BCM applies brakes after WoffW
Nose Gear - Snubbers in the nose bay stop the wheels
(B) Which hydraulic system controls the nose-wheel steering?
HYD SYS 2
(B) What are the limits for the nose-wheel steering?
Angle varies with groundspeed
0 to 40 knots: + 76°s
41 to 100 knots: Decreases linearly from 76°s to 7°s
