Hydraulics Flashcards
What components are included in Hydraulic System 1?
- Rudder (Upper Actuator)
- Elevator (L Outboard)
- Multi-Function Spoilers (L & R panels 3 & 4)
- Outboard Brakes,
- Ground Spoilers (L & R panel 2)
- Thrust Reverser (Engine 1)
- Emergency Parking Brake
NOTE: Outboard Brakes or emergency Parking Brake not shown on picture
What components are included in Hydraulic System 2?
Elevator (L & R Inboard)
Ailerons (L & R Inboard)
Thrust Reverser (Engine 2)
Multi-Function Spoilers (L & R panels 5)
Ground Spoilers (L & R panel 1) Brakes (Inboard)
Landing Gear
Nose Wheel Steering, Emergency Parking Brake
What components are included in Hydraulic System 3?
Elevator (R. Outboard)
Rudder (Lower Actuator) Ailerons (L & R Outboard)
What are the key features of Hydraulic System 1?
1 reservoir
1 Engine Driven Pump (EDP)
1 AC Motor Pump (ACMP) as back-up for EDP
2 accumulators
What distinguishes Hydraulic System 2 from Hydraulic System 1?
Identical to Hydraulic System 1 with exceptions: allows for single-engine taxi, activates ACMP 2 for nose wheel steering and inboard brakes if only engine 1 is operating, uses PTU for hydraulic pressure to aid in landing gear operation if engine 2 or EDP 2 fails.
What are the components of Hydraulic System 3?
1 reservoir, 2 AC Motor Pumps (ACMP A and B), 1 accumulator
What is the primary pump in Hydraulic System 3?
Pump A is the primary pump.
What are the operational positions of Pump A?
The pump is either ON or OFF.
What is the backup pump in Hydraulic System 3?
Pump B is the backup pump.
What are the operational positions knobs of Pump B?
The pump has three positions: OFF, AUTO, or ON.
When does Pump B turn on automatically?
In AUTO, ACMP B will turn on automatically with a failure of ACMP A.
What does the accumulator in System 3 provide during an electrical emergency?
It provides hydraulic power to the associated flight controls
.
From the beginning of RAT deployment until AC ESS BUS powers the ACMP 3A.
What activates the ACMP in flight?
System logic activates ACMP in case of EDP failure or flaps selected to any position greater than 0°.
What activates the ACMP on the ground?
System logic activates ACMP in case of flaps selected to any position greater than 0° and thrust levers set to takeoff thrust or groundspeed greater than 50 knots.
What is the purpose of the accumulators in Systems 1 and 2?
They are used for ‘shock absorption’ in the system and for emergency parking brake use.
What is the purpose of the accumulator in System 3?
It is used during an electrical emergency to temporarily provide hydraulics to the flight controls.
What happens at 100°C in Hydraulic Systems?
HYD # HI TEMP CAUTION EICAS is triggered.
What happens at 125°C in Hydraulic Systems?
Respective SOV closes automatically
Both AC pumps for SYS 3 turn OFF.
What happens at 145°C in Hydraulic Systems?
HYD # OVERHEAT WARNING EICAS is triggered.
Why is the message for system 3 inhibited during an electrical emergency.
To avoid shutting down the only source of hydraulics.
How many hydraulic systems are on the airplane?
3 Independent systems: HYD 1, HYD 2, and HYD 3
What systems use hydraulic power?
Flight controls
Spoilers
Landing gear
Nose wheel steering
Wheel brakes
Thrust reversers
Can hydraulic fluid be transferred between each system?
No
How many hydraulic pumps are on the airplane?
7 total: 2 EDPs (Engine Driven Pumps), 4 ACMPs (AC Motor Pumps), 1 PTU
What are the basic components of the hydraulic systems?
Reservoir, Pumps, Accumulator
What is the purpose of the accumulator?
Helps to maintain constant pressure by covering transient demands and helps to avoid pump cavitation
When will ACMP 1 or 2 automatically activate?
Ground: Flaps > 0, and TL set to TOGA, OR Groundspeed > 50 kts (Remains on for 60 seconds after TL at TOGA)
Flight: Engine failure or EDP failure, OR Flaps > 0 (Remains on for 60 seconds after landing)
What are some important items controlled by the HYD 2 system?
Landing gear
Nose wheel steering
Inboard brakes
What is the PTU?
Power Transfer Unit
Mechanical pump that uses HYD 1 power to provide HYD 2 pressure.
What is the primary purpose of the PTU?
To allow landing gear retraction and extension in the event of an engine 2 or EDP 2 failure.
When will the PTU automatically activate?
During takeoff and landing with flaps > 0, if Engine 2 fails, or EDP 2 fails.
Must have above 12% quantity in #2 Hydraulic Reservoir and Airplane is Airborne. Engine #1 EDP must be operational.
How is single engine taxi possible if nose wheel steering is on HYD 2?
Releasing the parking brake activates ACMP 2.
What is the primary purpose of the HYD 3 system?
Back-up for the Flight controls.
Why does HYD ACMP 3A pump switch have an ON position and HYD ACMP 3B have an AUTO position?
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 with normal AC power.
What, if any, HYD ACMP will function if the RAT is the only power source?
HYD ACMP 3A only with no backup.
In an electrical emergency what provides hydraulic pressure to flight controls until the RAT comes online?
HYD 3 accumulator.
After 8 seconds the RAT will power ACMP 3A.
In an electrical emergency can HYD 3 system power requirements overload the RAT?
No. A flow limiter valve and a pump unloader valve are used to reduce flow and limits pump electrical power draw to prevent a RAT stall.
