Hydraulics Questions

Question 1

How many hydraulic systems are on the airplane?

Answer 1

• 3 Independent systems

- HYD 1, HYD 2, and HYD 3

Question 2

What system use hydraulic power?

Answer 2

• Flight controls
• Spoilers
• Landing Gear
• Nose wheel steering
• Wheel brakes
• Thrust reversers

Question 3

Can hydraulic fluid be transferred between each system?

Answer 3

• No

Question 4

How man hydraulic pumps are on the airplane?

Answer 4

- 6 total 2 EDPs (engine driven pumps) 
              4 ACMPs (AC motor pumps)

Question 5

What are the basic components of the hydraulic system?

Answer 5

• Reservoir
• Pumps
• Accumulator

Question 6

What is the purpose of the accumulator?

Answer 6

• Helps to maintain constant pressure by covering transient demands
• Helps to avoid pumps cavitation

Question 7

When will ACMP 1 or 2 automatically active?

Answer 7

• Ground
  
  • Flaps > 0 and
  • TL set T/O or
  • Groundspeed > 50 kt
• Flight
  
  • Engine failure or EDP failure
  • 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 pumps 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 ACMP 2

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 & B pump switch position ON & AUTO respectively?

Answer 14

• HYD ACMP 3A pump is primary and has no automation

- HYD ACMP 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 ACMP 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.