Hydraulic Systems Flashcards
Can hydraulic fluid be transferred between the systems?
No
How many hydraulic pumps are on the airplane?
6 total
- 2 engine driven pumps
- 4 AC motor pumps (ACMP’s)
When will ACMP 1 or 2 automatically activate?
Ground:
- Flaps >0 and Thrust Levers set to T/O or
- Groundspeed > 50 kts
Inflight:
- Engine failure or EDP failure
- Flaps >0
What is the primary purpose of HYD 3 system?
Backup for the Primary Flight Controls
When will the PTU automatically activate?
During takeoff and landing with flaps >0 or if
Engine 2 fails or EDP 2 fails
What happens when the fluid tempurature reaches 125 degrees C?
The Shutoff Valve (SoV). This isolates the EDP 2 from the respective hydraulic flow line
What is the purpose of the accumulator?
- Helps to maintain constant pressure by covering transient demands
- Helps to avoid pump cavitation
Why are HYD ACMP 3A & B pump switch positions “On” and “Auto” Respectively?
HYD ACMP 3A pump is primary and has no automation
HYD ACMP 3B pump is a backup and automatically activates if ACMP 3A fails
What are the two Hyd Sys 3 dedicated valves used in an electrtical emergency to avoid overload in the RAT?
Pump Unloader Valve
Flow Limiter Valve
What, if any, HYD ACMP will function if the RAT is the only power source?
HYD ACMP 3A only
In an electrical emergency can HYD 3 system
power requirements overload the RAT?
No
A flow limiter valve is used to reduce flow and limits
pump electrical power draw to prevent RAT stall
At what temperature will the Shutoff Valve automatically Actuate?
125 degrees C
What are the basic components of the hydraulic system?
- Reservoir
- Pumps
- Accumulator
What is the primary purpose of the PTU?
To allow landing gear retraction in the event of an ENG 2 or EDP 2 failure
What are some important items controlled by HYD 2 system?
- Landing gear
- Nose wheel steering
- Inboard brakes
When will the HYD 2 HI TEMP EICAS Caution message by displayed?
100 degrees C
What systems use hydraulic power?
- Flight controls
- Spoilers
- Landing gear
- Nose wheel steering
- Wheel brakes
- Thrust reversers
When will the Electric Hydraulic Pump 2 automatically shutoff?
6 minutes after parking break has been set
When will the Electic Hydraulic Pump 2 automatically activate on the ground?
Engine 1 running and parking break released
During Eng 1 start (once N2 reaches 40%) if parking break has been set within the last 6 minutes
NOTE: Electric Pump shuts off automatically in 6 minutes after Parking Break
How long will the Hydraulic Pumps be active during landing operations?
60 seconds (to avoid pressure variations in an event of engine failure)
What is the primary source of power in the Hydraulic System?
Engine Driven Pump (EDP)
Where are the Quantity Measuring and Tempurature Transducers located?
Inside their respective Reservoirs
At what tempurature will the HYD 2 OVERHEAT EICAS warning message appear?
145 degrees C
What is the PTU?
Power Transfer Unit
Mechanical pump that uses HYD 1 power to provide HYD 2 pressure
How many Hydraulic systems are on the plane?
3 independent systems
In an electrical emergency what provides hydraulic
pressure to flight control until the RAT comes online?
HYD 3 accumulator
After 8 seconds the RAT will power ACMP 3
