HYDRAULIC SYSTEM

Question 1

What’s the purpose of a priority valve?

Answer 1

It’s a modulating valve giving priority to the flight controls over:
• Landing gear
• Main door
• Steering

Typically occurs when a #1 engine failure on T/O

Question 2

What’s the max volume of:
• Engine driven hyd. pump
• Electric hyd. pump

Answer 2

• Engine hyd. pump: 10 gls per/min (Max)

* Electric hyd. pump: 0.9 gls per/min (Max)

Question 3

Electric hydraulic pump

• Location
• PSI
• Volume output

Answer 3

• Located in the hydraulic bay
• 2900 psi
• 1/10th volume of engine pump

Question 4

How many PSI do

Engine driven hyd. pump
Electric driven hyd. pump

 provide?

Answer 4

Engine pump 3000 psi

Electric pump 2900 psi

Question 5

Hydraulic Reservoir

Answer 5

Is pressurized by a small piston (3000 psi) connected to a big piston (lower press) to avoid pump cavitation.

Question 6

Where is the temp. sensor and QTY sensor?

Answer 6

In a hydraulic reservoir

Question 7

Which control systems are backed up by both hyd. systems?

Answer 7

Rudder & Ailerons

Question 8

What is supplied by Hyd. system #2? (6)

Answer 8

1. Ailerons
2. Rudders
3. Outboard spoilers / speed brakes
4. Inboard brakes
5. Right thrust reversers
6. Emergency brakes

Question 9

Hyd. Sys #2 Accumulator

Answer 9

• Located in the #2 Hyd. bay
• Used for: emergency / parking brake
good for 6 strokes
or if set for 24 hours

Question 10

What is supplied by Hydraulic System #1? (8)

Answer 10

Ailerons/ Rudders/ Inboard spoiler/ Outboard brakes/ Left thrust reverser/ Landing gear/ Steering/ Main door

Question 11

Hydraulic servicing is accomplished by:

Answer 11

Connecting a “mule” to the quick connectors and adding fluid.

     ⬅️ External Power Supply

Question 12

Electric Hyd. pump AUTO

When does it come on? (2)

Answer 12

Engine driven hydraulic output drops below 1600 psi or N2 drops below 56.4% RPM

Question 13

Hydraulic system #1 Accumulator

Answer 13

• Located in the FWD HYD bay
• Used for:
a) Air stair door ops ( 4 ops )
b) Shock protection
c) Assist with retraction landing gear

Question 14

What does door blocked mean?

Answer 14

Solenoid Valve Failure. The main door actuator line remained pressurized when the door was closed

Question 15

Describe Air stair door operation?

Answer 15

2 HYD actuators powered by Sys. #1 or by Accumulator

Question 16

How to unblock blocked door?

Answer 16

Use alternate opening valve in cockpit or nose compartment bay (turn right and hold for 2
Min)