Hydraulics

Question 1

If you lose all DC power, what happens to Speed Brakes if they were extended?

Answer 1

They would blow to trail
Reason: Safety valves spring open, releasing hydraulic pressure instantly, allowing aerodynamic forces to push speed brakes closed to maintain aerodynamic stability.

Question 2

If you lose all DC power, what happens to Flaps if they were extended?

Answer 2

Remain locked in their current position.
No safety valve; hydraulic fluid remains trapped (hydraulic lock), holding flaps firmly in place. Minimal aerodynamic force prevents unintended flap movement.

Question 3

If you had a Hydraulic issue and had flaps extended what could/would you do?

Answer 3

Electrically operated, so I can just move the flaps back to 0 and they would partially retract due to airload.

Question 4

The HYD PRESS ON annunciator illuminates when system pressure rises to approximately:

Answer 4

185 psi and turns off at 155 psi

Question 5

The open center hydraulic system operates which four systems?

Answer 5

Landing Gear
Speed Brakes
Flaps
Thrust Attenuator’s

Question 6

Why is the Hydraulic Reservoir pressurized?

Answer 6

To prevent cavitation and improve pump efficiency

Question 7

What pressurizes the Hydraulic Reservoir?

Answer 7

Bleed air at 23 psi

Question 8

How much fluid is held in the Hydraulic Reservoir?

Answer 8

2 liters/ 0.54 Gallons

Question 9

Where are the filters in the Hydraulic system located?

Answer 9

One after each pump just before entering the system and one on the return line prior to the reservoir

Question 10

What is the micron rating on the filters located after the pumps?

Answer 10

5 microns nominal
15 microns absolute

Question 11

What is the micron rating on the filter located on the return line prior to the reservoir?

Answer 11

6 GPM nominal

Question 12

At what psi does the bypass valve open on all three filters?

Answer 12

100 psi

Question 13

What is the standard GPM for our hydraulic system?

Answer 13

3 GPM

Question 14

At what GPM would the HYD FLOW LOW annunciator be triggered?

Answer 14

0.35 - 0.55 GPM

Question 15

At what PSI does the main relief valve crack and fully open at?

Answer 15

Cracks at 1350
Fully open at 1500