Hydraulic Flashcards
How many hyd pumps are on the airplane?
6 total:
2 Eng driven pumps
4 AC motor pumps
(PTU makes 7 pumps)
How many hydraulic systems are on the airplane?
3 independent systems
What are the 6 systems that use hydraulic power?
SNLWTF
2. Spoilers
4. Nose wheel steering
3. Landing Gear
5. Wheel Brakes
6. Thrust Reversers
1. Flight Controls
Can hydraulic fluid be transferred between each system?
No
What are the 3 basic components of the hydraulic systems?
- Reservoir
- Pumps
- Accumulators
What is the purpose of the accumulators?
- Helps to maintain constant pressure by covering transient
demands - Helps to avoid cavitation in reservoir
When will Hyd ACMP 1 or 2 activate on ground and in flight?
Ground:
Ground:
1. Flaps > 0
2. TL set to T/O, or
3. GS > 50 kts
Takeoff:
in TOGA, activated for 60 seconds to avoid abrupt hydraulic
pressure variations in an event of engine failure
In-flight:
1. Eng or EDP failure
2. Flaps > 0
Hydraulic System 1
Rudder (Upper Actuator)
Elevator (L Outboard)
Thrust Reverser (Engine 1)
Multi-Function Spoilers (L & R panels 3 & 4)
Ground Spoilers (L & R panel 2)
Outboard Brakes
Emergency Parking Brake
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
Hydraulic System 3
Elevator (R Outboard)
Rudder (Lower Actuator)
Ailerons (L & R Outboard)
What are some of the important systems run on HYD 2?
- Landing gear
- Inboard brakes
- Nose-wheel steering
What is the PTU?
What is the PTU?
The power transfer unit (PTU) is a mechanical pump that uses
HYD 1 POWER to provide HYD 2 PRESSURE
What is the primary purpose of the PTU?
What is the primary purpose of the PTU?
Allows for landing gear retraction and extension in the event that
ENG 2 or EDP 2 fails
When will the PTU automatically activate?
If system meets requirements
When will the PTU automatically activate?
If system meets requirements
During takeoff and landing with flaps > 0, if
- Flaps > 0
- Eng 1 not fail
- Hyd 2 Reservoir Fluid Level above 12%
then PTU comes on automatically - ENG 2 or EDP Fail
How is single engine taxi possible if nose wheel steering is
on HYD 2?
How is single engine taxi possible if nose wheel steering is
on HYD 2?
Releasing the parking brake commands ACMP 2 to turn on
What is the primary purpose of HYD 3?
What is the primary purpose of HYD 3?
To back up the flight controls
Why does HYD ACMP 3A pump have an ON switch and HYD
3B have an AUTO position?
Why does HYD ACMP 3A pump have an ON switch and HYD
3B have an AUTO position?
- HYD 3A is primary and has no automation
- 3B is a backup in the event 3A fails
Which hydraulic pump will function if the RAT is the only
source of AC power?
Which hydraulic pump will function if the RAT is the only
source of AC power?
Only ACMP 3A (AC ESS Bus)
In an electrical emergency, what provides hydraulic pressure
to flight controls until the RAT comes online?
In an electrical emergency, what provides hydraulic pressure
to flight controls until the RAT comes online?
- System 3 Accumulator during the 8 seconds it takes to deploy
RAT - RAT powers ACMP 3A once RAT is online
What is the purpose of the Hydraulic system 3 accumulator?
What is the purpose of the Hyd system 3 accumulator?
Temporarily provides hydraulics to the flight controls during an electrical emergency. (from the beginning of RAT deployment until AC ESS Bus powers the AC pump 3A)
In an electrical emergency, can HYD 3 system power
requirements overload the RAT?
In an electrical emergency, can HYD 3 system power
requirements overload the RAT?
No, there’s a flow limiter valve and pump unloader valve that is used to
reduce the flow and limits pump electrical draw to prevent a RAT
stall
What kind of hydraulic fluid does the 175 use?
What kind of hydraulic fluid does the 175 use?
Skydrol Hydraulic Fluid
What is the nominal hydraulic pressure?
What is the nominal hydraulic pressure?
3000 PSIG
Hyd ACMP1B and Hyd ACMP2B is located on what bus?
Hyd ACMP1B and Hyd ACMP2B is located on what bus?
AC Bus 2 for ACMP1B and AC Bus 1 for ACMP2B
Opposite buses