Hydraulics Flashcards
Which pumps supply normal hydraulic pressure to the Hydraulic system?
The three “A” pumps which operate continuously
How many ACMP pumps may be operating on the ground while on APU or external AC power?
2
How is the hydraulic reservoir quantities accurately checked in the flight compartment before engine
start?
Turn on the “B” and PTU pumps to pressurize the system
Use the hydraulic synoptic page to read the value
What is the nominal hydraulic system pressure?
3000psi
What type of hydraulic fluid is used in the airplane? (FCOM2, Airplane General)
Phosphate Ester Type IV or V, low density fluid (Skydrol)
When in AUTO, when will ACMP 1B operate?
When the airplane is in the takeoff or approach phase
EDP 1A failed or LH engine is not running in flight (low pressure in the number 1 system)
The PTU is operating and either EDP 2A has failed or RH engine is not running
When in AUTO, when will ACMP 3B operate?
When the airplane is in the takeoff or approach phase
ACMP 3A has failed in flight (pressure low)
When in AUTO, when will the PTU operate?
When the airplane is in the takeoff or approach phase
EDP 2A has failed
RH engine is not running in flight
On the ground with only the LH engine running and the Parking Brake handle released
How are the EDP HYD SOVs closed?
The L(R) HYD SOV guarded PBA on the HYDRAULIC panel is pressed
The L(R) ENG FIRE guarded PBA on the FIRE panel is pressed
When HYD systems 1 and 2 reservoirs detect excessive fluid temperature (125°C), the valves
close automatically
What are the electrically driven hydraulic pumps and their associated electrical power source?
1B – AC BUS 2
3A – AC BUS 2
3B – AC BUS 1
PTU – DC BUS 1 (PTU Select Valve)
Which hydraulic system can be powered by the Ram Air Turbine (RAT)?
System 3
What should the RAT/bootstrap accumulator pre-charge pressure be when the hydraulic system is
depressurized?
1,100 ±100psi
Note: This is for 15°C. At other temperatures, there is a correction placard showing valid
pressure ranges for each temperature near the gauge.
What should the brake accumulators pre-charge pressure be when the hydraulic system is depressurized?
650 ±100psi
How is hydraulic fluid cooled?
Heat exchangers located in the fuel tanks
Which hydraulic pumps are available/operating during single generator operations in flight?
Operating engine hydraulic pumps (EDP)
A maximum of 2 ACMPs can be powered by a single generator
Above 43,000ft, only one ACMP can be powered by the APU generator
