Hydraulic System Flashcards
Each demand pump has a switch titled “OFF, AUTO, ON.” Describe this switch and its positions.
OFF: Demand pump off
AUTO: Turns on when related engine pump pressure low or when related fuel control is in CUTOFF.
(For demand pumps 1 and 4, also turns on when TE flaps in transit, or flaps extend past 1 in flight.)
ON: Turns on demand pump
Each engine hydraulic pump has a switch. Describe this switch.
Pushed in= ON: Engine pump pressurizes when engine rotates
Pushed out=OFF: Engine pump off
Amber PRESS light: Engine hydraulic pump pressure low
Above each demand pump switch, there is a light. What does it mean if this light is on with the amber PRESS?
-Demand pump pressure low
-Demand pump OFF or AUX
-or, demand pump has failed
Each hydraulic system has an amber SYS FAULT light. What does seeing this light mean?
-Low pressure
-Low quantity
-High temp
What would a full hydraulic reservoir indicate on the hydraulic synoptic?
1.00 is full
What is the nominal pressure of the hydraulic system?
3,000 PSI
On the synoptic, you see a magenta RF. What does this mean?
Displays only on ground-refill needed.
On the synoptic, you see a magenta LO. What does this mean?
Low hydraulic reservoir quantity
How many hydraulic systems?
4 independent systems
What are all of the items that are hydraulically powered?
- primary flight controls
- autopilot servos
- spoilers
- stabilizer trim
- elevator feel
- landing gear
- flaps
- brakes
- nosewheel steering/body gear steering
Each system is powered by how many pumps? What types? How are they powered
-Each system has at 1 demand pump and 1 engine driven pump
-System 1 and 4 demand pumps powered by bleed air
-System 2 and 3 demand pumps electric
-System 4 also has an electric AUX pump for ground handling
How is each hydraulic reservoir pressurized? Why?
-Bleed air.
-To prevent pump cavitation, and to ensure positive pressure in high demand conditions.
Which system powers the flight controls? Is there manual reversion?
ALL hydraulic systems redundantly power the flight controls.
No manual reversion.
There are 3 autopilot servos, all hydraulically powered. Left, center and right. Which hydraulic system powers each?
Left: System 3
Center: System 1
Right: System 2
What systems power the spoilers?
2, 3 and 4
How many hydraulic reservoirs?
1 per system.
Normally, which pump provides pressure to the hydraulic system? What is its backup?
-Normal: EDP (Engine driven pump)
-Backup: Demand pump. Automatically operates during periods of high demand, such as flap in transit and gear retraction, or if the EDP fails.
When do demand pumps automatically turn on?
ALL: -When EDP pressure low
-When related fuel selector is
in CUTOFF
Demand pump 1 and 4 only:
-When trailing edge flaps in
transit
-When flaps extended greater
than flaps 1 in flight
When hydraulic system 4 AUX pump is selected, does the demand pump run?
No. The demand pump is OFF. Only the electric AUX pump would run.
An EDP operates if______
The pump switch is ON, the engine is running, the fire switch is not pulled.
You see a RSVR PRESS white indication on the hydraulic synoptic page. But the SYS FAULT light is not illuminated overhead.. what does this mean?
It means the bleed air pressure to a reservoir is low.
What measures hydraulic quantity?
HYQUIM (Hydraulic Quantity Interface Module.)
Note: Can give erroneous indications if it faults due to overvoltage
Where is the hydraulic reservoir located?
In each respective engine pilon
Big ticket Items on System 1
-Nose and body gear (operation and steering)
-INBOARD Trailing edge flaps
Big ticket items on system 4
-Wing gear
-OUTBOARD Trailing edge flaps
Big ticket Items on system 2 and 3
-Upper and lower rudder
-upper and lower yaw damper
-Stab trim
