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What type of brakes?
how do the work?
- Four carbon Brakes.
- BCU gets command from the pedal transducers and commands the four brake control valves to modulate pressure to the brakes.
What system are the outboard brakes on?
Inboard? and what bus are they tied to?
- #1 DC ESS BUS 1
- #2 DC ESS BUS 2
What is Antiskid protection?
- Compares wheel speeds to each other.
- If one is slower than the other releases pressure.
- only releases pressure
- deactivates below 10 kts.
What is locked wheel protection?
- compares speeds of wheels that if one is less than 30% lower than the other brake pressure is relieved.
- Activates above 30 kts and deactivates below 30 kts.
- the 30% is in case you are using differential breaking.
What is touchdown Protection?
What happens if both proximity switches fail ?
- Inhibits braking until 3 seconds or 50 kts wheel speed after touchdown.
- braking will be available above 10 kts wheel speed.
- below 10 kts loss of main braking but still emergency brake.
Do we still get beake protections with emergency brake?
When the landing gear is retracted what stops the mains? and nose wheel from spinning?
- Brakes are applied to the mains
- snubber on the nose.
What does BRAKE ON light tell us?
That brake pressure is being applies to the wheel brakes
what hydraulics system is the emergency/parking brake on?
How many applications does the accumulator give us and for how long?
- six full brake applications for 24 hours.
What are the limits of nose wheel steering?
What system is nosewheel steering controlled by?
- 76* total,71*wheel steering, 5*pedals
- Hydraulic system 1
How does the steering know when to engage?
ECM is energized when on the ground signaling the hydraulics to pressurize the steering actuator.
What controls the Landing gear
- Landing gear electronic unit
how many proximity switches does the gear have and where are they?
- Five in total
- 2 on each main landing gear
- 1 on the nose landing gear. only goes to nosewheel steering and thrust reversers.
How many sensors must agree
- if 4 thatn 3 agree
- if 3 than 2 must agree
- if 2 than 2 must agree
What system powers the Landing gear?
What does the accumulator do ?
- system #1
- assists in retraction and prevents pressure fluctations.
How does the gear retract?
discribe the sequence for gear retraction?
When the gear lever is lifted up the LGEU sends a signal to the Gear doors and landing gear. Allowing hydraulic #1 pressure to reach the landing gear and downlock actuators. LGEU will signal back to the EICAS that the gear is up and locked when uplock boxes are actuated.
What happens in gear extension?
When commanded LGEU commands the landing gear electroslave and nose gear doors solenoid valve. Hydraulic pressure goes to the main landing gear, door solenoid and up unlock actuator. EICAS message is received when the gear downlock boxes are actuated.
How does electrical overide work?
- Bypasses the LGEU and goes directly to the landing gear electroslave and nose gear door solenoid valve.
- After gear is extended move the switch back to normal to deenergize the LG electroslave and depressureize the lines.
What happens in a frefall gear extension?
Releases the uplocks letting gear freefallwith gravity.
When will the gear warning activation occur?
- RA<1200ft, flaps <22, 1 thrust,< 59,or 2 <45
- Flaps 45
- Loss of RA