HYDRAULIC SYSTEM

Question 1

What systems require hydraulic pressure?

Answer 1

Landing Gear, Wheel Brakes, Pusher, Rudder Boost, Spoiler/Speed Brakes.

Question 2

What provides variable flow and pressure to the system? And at what rate?

Answer 2

Two engine-driven hydraulic pumps at 3000psi (located on the accessory gear box
of each engine)

Question 3

In case of a hydraulic pump malfunction, what prevents rotation without
interfering with the continued operation of the engine?

Answer 3

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.

Question 4

What is the function of the Priority Valve?

Answer 4

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

Question 5

What encases the hydraulic fluid?

Answer 5

A (spring-biased bootstrap diaphragm type) reservoir.

50psi reservoir pressure, 3000psi system pressure

Question 6

How much can it hold?

Answer 6

Maximum 1.3 gals.

Question 7

What provides contamination protection for the system?

Answer 7

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).

Question 8

What would happen if the filter fails or is blocked by too much contamination?

Answer 8

A bypass valve will open to allow continued flow though the hydraulic system.

Question 9

What is available to indicate that the filters need to be replaced?

Answer 9

The filters have red “pop-up” differential pressure indicators to provide a visual
indication when the filters need to be replaced.

Question 10

How are the Fire Shutoff Valves closed?

Answer 10

Manually by the engine fire extinguisher shutoff buttons, automatically in case of
hydraulic system high temperature, or through the shutoff switches on the
hydraulic panel.

Question 11

What does a “HYD HI TEMP” CAS message indicate?

Answer 11

The hydraulic fluid temp has risen (to above 235+/- 7F) and both FSOV
automatically close.

Question 12

What does a “HYD LO PRES” CAS message indicate?

Answer 12

The system is not capable of providing flow at rated pressure.

Question 13

What does a “HYD SOV ½ FAIL” CAS message indicate?

Answer 13

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)