Hydraulics

Question 1

What systems use hydraulic power?

Answer 1

Flight controls
Spoilers
Landing gear
Nose steering
Brakes 
Thrust reversers

Question 2

Can hydraulic fluid be transferred between each system?

Answer 2

No

Question 3

How many hydraulic pumps are on the airplane?

Answer 3

6 total

2 EDP ( engine driven pumps)
4 ACMP (AC Motor Pump)

Question 4

What are the basic components of the hydraulic systems?

Answer 4

Reservoir
Pumps
Accumulator (2 on HYD 1/2, HYD 3 has 1)

Question 5

What is the purpose of the accumulator?

Answer 5

Helps to maintain constant pressure by covering transient demands

Helps avoid pump cavitation

Question 6

When will ACMP 1 or 2 automatically activate on the ground?

Answer 6

Flaps > 0, and
TL set to T/O, or
Ground speed > 50 kts

Question 7

When will ACMP 1 or 2 automatically activate in flight?

Answer 7

Engine failure or EDP failure OR

Flaps > 0

Question 8

What are some important items controlled by HYD 2 system?

Answer 8

Landing gear
Nose wheel steering
Inboard brakes

Question 9

What is the PTU?

Answer 9

Power Transfer Unit

Mechanical pump that uses HYD 1 power to provide HYD 2 pressure

Question 10

What is the primary purpose of the PTU?

Answer 10

To allow landing gear retraction in the event of an engine 2 or EDP 2 failure

Question 11

When will the PTU automatically activate?

Answer 11

During takeoff and landing with flaps >0, if
Engine 2 fails, or
EDP 2 fails

Question 12

How is single engine taxi possible if nose wheel steering is on HYD 2?

Answer 12

Releasing the parking brake activates ACMP2

Question 13

What is the primary purpose of HYD 3 system?

Answer 13

Back-up for the flight controls

Question 14

Why are HYD ACMP 3A & 3B pump switch positions ON & AUTO respectively?

Answer 14

HYD 3A pump is primary and has no automation

HYD 3B pump is a back-up and automatically activates if ACMP 3A fails

Question 15

What, if any, HYD ACMP will function if the RAT is the only power source?

Answer 15

HYD 3A only

Question 16

In an electrical emergency, what provides hydraulic pressure to flight controls until the RAT comes online?

Answer 16

HYD 3 accumulator

After 8 seconds the RAT will power ACMP 3A

Question 17

In an electrical emergency can HYD 3 system power requirements overload the RAT?

Answer 17

No, a flow limiter valve is used to reduce flow and limits pump electrical power draw to prevent a RAT stall

Question 18

How many hydraulic systems are on the airplane?

Answer 18

3 independent systems

HYD 1, HYD 2, and HYD 3