Hydraulic Flashcards
What is the function of system accumulator ?
Maintain a constant pressure by covering transient demand during normal operation
What is normal pressure in hydraulic ?
3000 psi (2500 psi when powered by RAT)
How many hydraulic system are there ?
Green, Blue, Yellow
Can hydraulic fluid be tranffered from one system to another ?
No
How many source does GREEN system has ?
-Engine driven pump
-PTU
How many source does BLUE system has ?
-Electrical pump
-RAT
How many source does YELLOW system has ?
-Engine driven pump
-Electrical pump
-Hand pump
-PTU
What is PTU ?
Power Tranfer Unit
A bidirectional power tranfer unit enable yellow system to pressurize green system and vice versa
When will PTU work automatically ?
Power transfer unit
When differential btw Green and Yellow is more than 500 psi
What is RAT ?
Ram Air Turbine, supplies pressure to Blue system and run emergency electric generator
When will RAT be deploy ?
Ram air turbine
-Automatically when lost AC 1 and AC 2
-Manualy by RAT MAN ON pb on Hydraulic panel and Emer electric panel
What is the diff of RAT MAN ON pb btw Hydraulic panel and Emer electric panel ?
-Pb on Hydraulic panel will only supplies hyrdraulic pressure to Blue
-Pb on Emer elec panel can supplies both hydraulic and electric.
What is priority valves ?
it can cut off hydraulic power to heavy user if hydraulic power get low.
Which systems are lost when priority valves close ?
* Green
* Yellow
* Blue
- Green: L/DG, slats,flaps
- Yellow: Flaps
- Blue: Emer Gen, Slats
What is the function of Fire Shut Off Valves ?
Located at upstream of engine driven pump, close when push ENG FIRE pbs to cut out hydraulic supply
What is Leak Measurement Valves ?
Locate upstream of primary flight control, which measure the leakage in each circuit.
How is hydraulic reservoir pressurized ?
Reservoir is pressurized by HP bleed air from engine 1 automatically. If bleed air press is too low, system will take bleed air press from cross bleed duct.
Why reservoir need to be pressurized ?
To prevent their pump from caviating
Which systems are supplied only from GREEN ?
- L/DG
- REV ENG 1
- Norm BRK
Which systems are supplied only from BLUE ?
EMER GEN
Which systems are supplied only from Yellow ?
- ALT/PARK BRK
- Cargo Door
- REV ENG 2
- NWS
FAULT lt in ENG PUMP pb ?
-Reservoir low level
-Reservoir low air press
-Reservoir overheat
-Pump press is low
Light go out when selected OFF except overheat
BLUE ELEC PUMP pb
-FAULT lt
-AUTO
AUTO: if AC power avail, electric pump operate
- In flight
- On ground when one engine run or BLUE PUMP OVRD pb pushed
FAULT lt
-Reservoir low level
-Reservoir low air press
-Reservoir overheat
-Pump press is low
-Pump overheat
Light go out when selected OFF except overheat
When will Yellow electric pump come on automatically ?
when operate cargo door
What happen in yellow system during cargo door operation ?
Other operations of yellow system are inhibited (except alternate brk and engine 2 rev)
FAULT lt in YELLOW ELLEC PUMP pb ?
-Reservoir low level
-Reservoir low air press
-Reservoir overheat
-Pump press is low
-Pump overheat
Light go out when selected OFF except overheat
When is PTU inhibited ?
-First engine start
-During and 40s after cargo door operation
How long does it take for RAT to extend and provide power ?
Ram air turbine
3s for extend, 5s for powering. Total 8s
Can RAT be stowed affter depploy ?
No, only on ground
During start up, when is BLUE system pressurized ?
Automatic after first engine start
Why you need to turn off PTU first when reservoir overheat ?
To avoid PTU pressurize the faulty system which will worsen the situation.
What does the amber level indication mean on the hydraulic quantity indicator ?
Warning level
When brake accumulator press is low, how can you recharge ?
Request clearence from ground then turn on the yellow electric pump
What happen with slats/flaps operation speed when lost 1 hyraulic press system ?
Green: 1/2 speed both
Yellow: 1/2 speed flaps
Blue: 1/2 speed slats
What does the BRAKES & ACCU PRESS triple indicator indicate ?
-Yellow press delivered to the brakes
- Yellow brake Accumulator press
How do you perform the brake check during initail taxi ?
Press the brake pedals to ensure a/c slow, and check the pressure on triple indicator is zero, indicating normal brake is working.
Can the a/c be flown with a loss of all hydraulic system ?
No, need at least 1 system
What is the purpose of hand pump ?
To provide yellow system hydraulic press to operate cargo door
FAULT lt in PTU pb ?
-Reservoir low level
-Reservoir low air press
-Reservoir overheat
Light go out when selected OFF except overheat
If FAULT lt in PTU pb is illuminate, are there any other indications on HYD panel ?
Yes, FAULT lt of respective ENG PUMP pb illuminate
