Landing Gear and Brakes Flashcards
How many weight-on-wheels proximity sensors are there
6
How many proximity sensor electronic modules (PSEM) are there
2
How any WOWs on each gear
2
What happens if 2 WOW sensors k. The same wheel are failed
PSEMs prohibit gear from being raised
When up, what holds the landing gear in place
Uplocks
How are the landing gear doors operated
Mechanically
How is the landing gear held in the down position
Downlock springs
What is the electrical override system
When the landing gear lever control box fails, the electrical override system bypasses the PSEM and commands the gear down normally
When do you use the alternate gear extension
When the hydraulic pressure is lost or electrical system fails
How does the alternate gear extension system work
Hyd pressure is released from all uplocks and the gear free falls into position
Which brake does hyd 1 control
Outboard
Which brake does hyd 2 control
Inboard
What are the main functions of Brake Control Modules
- Locked wheel protection
- antiskid protection
- Automatic wheel braking
- touchdown protection
What is locked wheel protection
The BCM compaira wheel speeds and releases brake pressure on the slower wheel if it is 33% slower to match speeds
Why the threshold for wheel lock protection
To allow for differential braking
Under what speed is antiskid protection not available
10kts
What is automatic wheel braking
Automatically stops the wheels from spinning while being retracted
What is touchdown protection and when is it deactivated
Prevents landing with main wheel brakes on.
Deactivated 3 secs after WOW has sensed landing or when wheel speed is above 50 kts
What powers the emergency/parking brake
Hyd 1 and 2
What happens to the emergency/parking brake if you lose hyd 1 and 2
Can still apply emergency brake 6 times because of the emergency brake accumulators
Are antiskid, touchdown, and locked wheel protection provided while auto braking
Yes
When will landing and RTO auto braking be disarmed
- selector switch is set to the OFF position
- pedal braking is applied if speed is above 60 kts and RTO is selected
- brake control system failure is detected (while speed below 60 and RTO selected)
- either thrust lever is advanced above idle during autobrake application.
Will autobrake discontinue on landing if manual brakes are applied
Yes, if pressed more than 20%
Which hyd system powers the nose wheel steering
2
