Hydraulics

Question 1

What controls the operation of the HYD system?

Answer 1

1 Hydraulic System Monitoring Unit (HSMU)

Question 2

How many HYD systems are there?

Answer 2

3 Independent continuously-operating Systems:
Green (Main)
Blue
Yellow

Question 3

Green System:
How many pumps does the green system have?

Answer 3

4 Pumps: 2 engine driven (each engine), 1 electric, 1 from RAT

Question 4

Green System:
When does the electric pump run?

Answer 4

Automatically when either engine fails in flight then select the landing gear lever up. It runs for 25 sec when the landing gear lever is selected up, to bring gear up within proper time. (Above 100kts)

Question 5

Blue System:
How many pumps does the Blue System have?

Answer 5

2 pumps:
- Engine 1 HYD pump
- 1 electric pump.

Question 6

Blue System:
When does the Blue electric pump come on?

What does it assist with?

Answer 6

Automatically in flight or when engine 1 fails and a loss of PRIM 1 or 3.

The electric pump runs automatically in flight to ensure sufficient authority on the electrical rudder to counteract the yaw sideslip induced by asymmetrical thrust.

Question 7

Yellow System:
How many pumps does the Yellow System have?

Answer 7

3 pumps:
- Engine 2 HYD pump
- 1 Electrical Pump
-1 Hand pump (For cargo door operation with no power)

Question 8

Yellow System:
When does the Yellow system electric pump turn on?

Answer 8

-Automatically when Engine 2 fails and Flap lever is not at 0 (to ensure flap retraction in proper time at takeoff). (Above 100kts)
- Automatically on the ground for Cargo door operation

Question 9

What does the Green system Priority Valve do?

Answer 9

• Designed to prioritize Flight Controls in a low pressure situation.
• In a case of low pressure the valve cuts off the following high draw items:
  Emergency Generator
  Nosewheel Steering
  Landing Gear

Question 10

Besides flight controls, what are major items on the Blue system?

Answer 10

• Alternate Brakes
• Parking Brake
• Brake accumulator

Question 11

What does the RAT provide?

Answer 11

Provides redundancy to the Green system.
Provides backup hydraulic power to the flight controls and/or the emergency generator. (2500PSI)

Question 12

When does the RAT automatically deploy?

Answer 12

• Engines 1 and 2 fail. (Loss of AC bus 1 and 2)
• Green and either blue or yellow fluid low level.

Question 13

Minimum airspeed for the RAT?

Answer 13

140kts

Question 14

What is a consideration when the RAT is powering the green system?

Answer 14

The aileron, elevator, and spoiler servo control operating speeds are reduced.