Hydraulics Flashcards
What components are on the #1 hydraulic system?
Brakes Anti-Skid Rudder (lower) Flaps PTU Inboard spoilers Elevator (outboard PCU)
How many hydraulic systems are there on the airplane?
Four. The two main hydraulic systems, the backup hydraulic system and the auxiliary system.
What components are on the #2 hydraulic system?
Landing gear Outboard spoilers Steering Elevator (center PCU) Rudder (upper PCU) Emergency brake
What are the max quantities for each hydraulic system?
System 1: 8 quarts
System 2: 12 quarts
System 3: 2 quarts
Auxiliary: 1 quart
What is the minimum quantity for dispatch?
40%
How many pumps are on the #1 system?
Two, an engine driven pump mounted on the prop reduction gearbox and an AC powered standby pump.
What is the primary power source for the standby hydraulic pump?
The right 115vAC BUS serves as the primary power source and the left 115vAC bus serves as the backup.
What is the backup for the #2 hydraulic system?
The PTU. If the #2 engine driven pump fails the PTU will serve as the backup. The PTU uses power from the #1 system to create hydraulic pressure on the #2 side.
What is the purpose of the #3 system?
Operates the inboard elevator PCUs in case both the number 1 and 2 systems both fail
What is the purpose of the Auxiliary Hydraulic System?
Provides hydraulic pressure to manually extend the landing gear to ensure they are locked in position after an alternate gear extension.
When will the standby hydraulic pump automatically activate?
If the number one engine fails OR the flaps are greater than 0° and the parking brake is released. The ON portion of the STBY HYD pushbutton will only illuminate if it is manually selected on. Pressure can be confirmed on the co-pilot’s MFD.
When will the PTU automatically activate on the ground?
If the number two engine fails OR the flaps are greater than 0° with the parking brake released.
What is the minimum parking brake pressure for starting the #1 engine? The #2 engine?
#1 engine: 1000 psi #2 engine: 500 psi
When will the PTU automatically activate in the air?
#1 Engine driven pump is operating normally System #2 quantity is available AND
Flaps are greater than 0° OR #2 hydraulic pressure is low OR #2 engine oil pressure is low
What do the ///// mean on the PTU pushbutton?
PTU is operating normally in either automatic or manual mode
Amber //// means that the PTU has failed to achieve normal pressure 5 seconds after being commanded on.
Explain how the #3 HYD ISO VALVE works
Pushing the #3 HYD ISO VALVE button will manually open the isolation valve allowing the #3 system to power the inboard elevator PCUs. If the number 1 and 2 systems have failed the valve will open automatically but the Amber light will not illuminate unless the button is pushed in.
The #1 system isolation valve is normally open but will close if fluid loss is detected in order to power:
PTU
Rudder (lower)
Elevator (outboard)
Flaps
The #1 system priority valve will close at 2100psi. This will cut off hydraulic pressure to:
PTU
Flaps
You will still have the: Brakes Anti skid Rudder Inboard spoilers Elevator
If either of the EDPs fail will the Standby Pump or PTU automatically activate?
No, they only activate in the case of ENGINE failure. If the EDP fails the standby pump or PTU need to be manually activated.
Like the #1 isolation valve, the #2 system also normally operates with an isolation valve in the open position. If this detects a fluid loss the isolation valve will close but you will still have power to:
The rudder and elevator
The #3 system is powered by a gas accumulator, with its pressure maintained by?
A DC motor pump which will keep pressure between 2600-3250psi
What does the #3 STBY HYD PUMP caution light mean?
3 system pressure has fallen below 900psi or the DCMP has been running for over 60 seconds on the ground.
When will the ELEVATOR PRESS caution light illuminate?
If the #3 HYD ISO valve fails open or is manually selected open. All 3 systems will be powering the elevator at the same time.
Where is the Auxiliary system located and how do we tell the reservoir quantity?
The reservoir for the #4 system is located in the lower right nose behind the crew O2 bottle. There is no quantity indication for the system.
