Part 1 - Chapter 5 - Hydraulic Systems

Question 1

Hydraulic services

Answer 1

• Flaps
• Speedbrakes
• Gear
• Wheelbrakes

Question 2

Hydraulic System basic components / flow

Answer 2

• Air pressurised reservoir feeds Engine Driven Pump
• 2 accumulators in event of EDR failure
• Larger accumulator provides one flap and speed break extension + emergency gear blowdown
• Small accumulator for 10 wheelbreak applications

Question 3

Engine driven pump (pressures)

Answer 3

• system pressure 1,200 -> pump coming online
• system pressure 1,500 -> pump output diverted to idle circuit

Question 4

Low pressure warning

Answer 4

<300 psi at EDR output

Question 5

Minimum permissible hydraulic pressure

Answer 5

1,250 psi (full 1,500 might not be obtained at idle rpm)

Question 6

Hydraulic pump failure - main accumulator pressure check

Answer 6

• 800 psi = no hydraulic pressure
• 1,500 psi = fully charged

Question 7

Hydraulic failure, accumulator pressure available - actions

Answer 7

• Retract speedbrakes
• Extend flaps as far as possible
• Lower gear (via emergency), the. select down on normal system