Hydraulics Flashcards
Name the sources of power for each of the hydraulic systems?
Green: ENG 1 driven pump
Blue: RAT and Electric pump
Yellow: ENG 2 driven pump, electric pump, hand pump
What services does each system deliver?
Green: flaps, gear, ailerons, spoilers, elevator, rudder, stab, rev 1, norm brakes
Blue: emer gen, slats, spoilers, ailerons, elevators, rudder
Yellow: flaps, NWS, Alt/park brakes, rev 2, elevator, rudder, stab, spoliers
How are hydraulic reservoirs pressurised and why?
Pressurised by the bleed system to prevent pump cavitation
What is the purpose of the priority valves?
To shut off high demand services in the event of loss of pressure
What is the purpose of hydraulic accumulators?
To remove variances in the system under load
Explain the purpose of the PTU?
Bi-directional power transfer unit, pressure from the yellow system drives a motor when the differential pressure>500psi. This motor then pressurises the green and vice versa.
Typical system pressure of the three hydraulic systems?
3000psi
What pressure would you expect to see when RAT is powering the blue system?
2500psi
At what psi does the system pressure indicate amber?
<1450psi
Of the dual hydraulic failures, which in your opinion is the worst and why?
Green+Blue due to controllability and complications in the go around
Which of the dual hydraulic failures maintains the aircraft in normal law?
Blue+yellow
Why is the gravity gear extension used on the blue and yellow dual hydraulic failure?
The priority valves are used to preserve the green system.
What is the purpose of extending the landing gear at 200kts with the green+blue failure?
To give better controllability as you do not have the slats.
Why in the green and yellow failure is flaps 3 selected before the gear is selected down?
The mean elevator position becomes the reference for centered side stick position before the gear comes down.
Which hydraulic systems power the ailerons?
Blue and green
