Hydraulic System Flashcards
What systems require hydraulic pressure? (5)
Landing Gear Wheel Brakes Pusher Rudder Boost Spoiler/Speed Brakes
What provides variable flow and pressure to the system? And at what rate?
Two engine-driven hydraulic pumps at 3000psi
located on the accessory gear box of each engine
In case of a hydraulic pump malfunction, what prevents rotation without interfering with the continued operation of the engine?
The hydraulic pump connecting shaft to the AGB has a recess designed to work as shaft shear point if the torque imposed by the hydraulic pump to the AGB exceeds limits.
What is the function of the Priority Valve?
It guarantees hydraulic power to the spoilers, stick pusher, rudder spring actuator or brakes by restricting the flow to the landing gear, if being used simultaneously.
What provides contamination protection for the system? HYD
Two disposable filter elements located on the lower portion of the manifold (one for low pressure return and one for the high pressure line; the filter can capture any particle greater than 5 microns).
What would happen if the filter fails or is blocked by too much contamination? HYD
A bypass valve will open to allow continued flow though the hydraulic system. This can be reset once by the crew. It is a sign of impending blockage.
What is available to indicate that the filters need to be replaced? HYD
The filters have red “pop-up” differential pressure indicators to provide a visual indication when the filters need to be replaced.
How are the Fire Shutoff Valves closed?
3
- Manually by the engine fire extinguisher shutoff buttons
- automatically in case of hydraulic system high temperature
- through the shutoff switches on the hydraulic panel.
What does a “HYD HI TEMP” CAS message indicate?
The hydraulic fluid temp has risen (to above 235+/- 7F) and both FSOV automatically close.
What does a “HYD LO PRES” CAS message indicate?
The system is not capable of providing flow at rated pressure.
What does a “HYD SOV 1⁄2 FAIL” CAS message indicate?
A Fire Shut Off Valve (FSOV) was commanded to close and did not close. (or a FSOV position does not agree with its switch position).
How many hydraulic reservoirs and accumulators?
1 reservoir and 1 (main) accumulator
Hydraulic Pump 2 gets PSI to?
2850 psi, because its pressurizing accumulator. If Hydraulic pump 1 is the only pump working pressure will be 3,000psi.
Above what value, following shutdown, should the hydraulic system pressure fall rapidly (1000 psi per second).
Greater than 1200 psi. If less than that, the accumulator needs to be serviced.
What is the purpose of the main hydraulic accumulator?
Stores pressure for periods of increased demand (simultaneous brake and ground spoiler application).
