Hydraulics

Question 0

When will PTU auto activate?

Answer 0

Inhibited on ground
Flaps greater than zero
EDP2 or engine 2 failure

Question 1

What’s on HYD system 2 that’s not on HYD 1?

Answer 1

Nose wheel steering
Landing gear
PTU

Question 2

What is the purpose of the HYD accumulator?

Answer 2

Helps avoid pump cavitation and covers transient load demands

System 1 and 2 have a dedicated HYD accumulator for parking brake
System 3 HYD accumulator provides temp power to primary flight controls

Question 3

When is a HYD system warm up required and where is the procedure found?

Answer 3

Reservoir temp. Below -18*C

Found in SOP chapter 6

Question 4

What’s on HYD system 3?

Answer 4

Right elevator
Lower actuator on rudder
Both ailerons

Question 5

What systems use HYD power?

Answer 5

Landing gear
Brakes
Steering 
Flight controls
Thrust reverser

Question 6

When will HYD ACMP 1&2 auto-activate?

Answer 6

GRND: flaps greater than zero, thrust to takeoff, and ground speed greater than 50kts

Flight: flaps greater than zero, EDP or Engine failure

Question 7

What is the PTU?

Answer 7

Mechanical pump that uses HYD power from system 1 to provide pressure for HYD system 2

Ensure landing gear operation in the events system 2 pressure is lost

Question 8

Can HYD fluid be transferred between systems?

Answer 8

No

Question 9

What does HYD 1/2 HIGH TEMP EICAS mean

Answer 9

HYD fluid has reached 100C and is nearing the auto shutoff temp of 125C

HYD OVERHEAT EICAS means 145*C and auto-shutoff has failed

Question 10

What happens to the HYD EDP during an engine failure?

Answer 10

FADEC commands the unload of the EDP to facilitate a windmill start

Question 11

What is the pump unloader valve?

Flow limiter?

Answer 11

Pump unloader reduces the discharge pressure of ACMP 3A to reduce the electrical power to start up the pump during RAT operation

Flow limiter reduces the flow provided by ACMP 3A so as not to stall the RAT the RAT