Hydraulics Flashcards
How many hydraulic systems are on the aircraft?
- 3
What systems use hydraulic power?
- Flight controls
- Spoilers
- Landing gear
- Nose wheel steering
- Wheel brakes
- Thrust reversers
Can hydraulic fluid be transferred between systems?
No
How many HYD pumps are there?
6, two engine-driven pumps (EDP) and four AC motor pumps (ACMP)
What are the basic components of the HYD systems?
- reservoir
- pumps
- accumulators
What is normal HYD pressure?
3000 PSI
How would you be alerted to a HYD low quantity or overtemp?
The HYD synoptic and EICAS
Where would I find a visual representation of the HYD system operation and parameters?
On the HYD synoptic page
Why wait after power-up prior to turning on any hydraulic pumps
To allow the flight controls to complete their built-in tests
How long after power-up before any HYD pumps should be turned on and why?
3 mins, to allow flight controls to complete built-in checks
What is the normal and alternate pump for each system?
- Systems 1 and 2: Engine driven pump, electric is backup
- System 3: 2 AC pumps, A is primary B is secondary. System operates completely automatically when the switches are in AUTO
What is the primary power source for HYD systems 1 and 2?
The respective engine driven pump (EDP)
What is used as a backup for the EDP?
The AC electric HYD pump
When is the electric HYD pump activated?
With the electric HYD pump selector knob in AUTO, whenever an EDP fails or for takeoff when the flaps are not set to the 0 position and the thrust lever are set to takeoff thrust or ground speed > 50 knots and for landing when flaps > 0
Why does electric HYD pump 2 automatically come on after engine 1 is started and the parking brake is released?
To provide nosewheel steering and inboard brakes during a single-engine taxi
What is the purpose of the accumulator?
- Helps maintain constant pressure by covering transient demands
- Helps to avoid pump cavitation
How would you be alerted to a HYD low quantity or overtemp?
On the EICAS and confirmed on the HYD synoptic
Can we disable the engine driven hydraulic pump?
No, but you can close the HYD SOV using the ENG PUMP SHUTOFF button which will isolate the pump.