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Utility Hydraulics Flashcards

(64 cards)

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1
Q

What are the main components of utility hydraulics?

A

APU start system, main engine start, power steering, swivel locks, brakes, cargo hook, hoist

These components are interconnected but separated by selector valves.

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2
Q

What drives the utility hydraulic pump?

A

AGB (Accessory Gearbox)

If no AGB is available, some systems can use pressure from the 200 cu in accumulator for a limited time.

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3
Q

What is the maximum pressure that the utility hydraulic system can achieve?

A

3125 psi

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4
Q

How is fluid supplied to the 200 cu in accumulator?

A

Pressurized fluid from the utility reservoir

The fluid is pressurized to 3125 psi by the utility hydraulic pump.

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5
Q

What allows the pilot to select the valve to open when the system is not online?

A

A switch in the cockpit

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6
Q

What is the purpose of the manual control valve in the ramp area?

A

To pump up the accumulator for APU start

The valve must be in NORMAL position to pressurize the accumulator.

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7
Q

Fill in the blank: The hydraulic electric motor pump used to fill the accumulator is called the _______.

A

EPUSHA

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8
Q

What is the rated capacity of the fixed displacement hydraulic pump in the EPUSHA?

A

0.71 ppm at 2150 rpm

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9
Q

What is the preload pressure of the internal floating separator piston in the 200 cu in accumulator?

A

1400 psi

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10
Q

Where is the utility reservoir located?

A

Above and right of aft transmission

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11
Q

What is the function of the check valve in the filler output port?

A

To keep system pressure from coming back into the filter

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12
Q

How much fluid can the filler tank hold?

A

1 quart

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13
Q

True or False: The level reading of the utility reservoir will be the same whether the ramp is installed or not.

A

False

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14
Q

What happens to the pressure of the system when the utility system is pressurized?

A

The reservoir is pressurized by taking fluid from a 25 cu in accumulator

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15
Q

What are the two functions of the APU motor/pump?

A

To start the APU and to pump once the APU is running

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16
Q

What is the purpose of the APU start valve?

A

To shut off the APU start and open the aux gear box motor valve

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17
Q

What does the AGB motor do?

A

It rotates and powers the accessory gear box

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18
Q

What type of pump is the utility hydraulic pump?

A

Constant pressure type pump that is self adjusting to produce 3,350 psi

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19
Q

What is the capacity of the smaller accumulator?

A

25 cu in

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20
Q

What is the pre-load pressure for the 25 cu in accumulator?

A

1,400 psi

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21
Q

What is the function of the isolation valve?

A

To retain pressure in the 200 cu in accumulator when rotors and APU are shut down

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22
Q

How can pressure from the utility pump pass through the isolation valve?

A

Through internal drillings without needing to select the valve ON

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23
Q

What must be done to operate the isolation valve?

A

Select the valve to ON in the overhead panel with battery ON

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24
Q

What happens when the APU or engines are started?

A

The isolation valve automatically closes to remove utility pressure from subsystems

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25
True or False: APU or engines can be started during ground taxiing.
False
26
Where is the utility hydraulic system switch located?
On the hydraulic control panel
27
What does the utility hydraulic system switch control?
The utility dual solenoid valve
28
What happens when the utility hydraulic system switch is turned ON?
DC emergency bus supplies power to the solenoid valve directing pressure to subsystems
29
What must be done if fluid from the utility hydraulic system is used?
Replace it with either the hand pump or the EPUSHA
30
What is the function of the cooler in the utility hydraulic system?
To cool pressurized fluid flowing through the return line
31
What activates the cooler fan motor?
Current from the solenoid when fluid temperature reaches 68C
32
What temperature range does the overtemp thermostatic switch activate?
134.4-141.1C
33
What does the UTIL HOT caution light indicate?
Fluid temperature exceeds safe levels
34
What is the operational pressure range for the hydraulic pressure gauge?
2,700-3,500 psi
35
What type of signal does the pressure transmitter generate?
An electrical signal proportional to the pressure of hydraulic fluid
36
What is the scale range of the hydraulic pressure gauge?
0-4000 psi
37
What is the hydraulic pressure supplied to hydraulic starters during engine start?
4,000 psi ## Footnote This pressure is supplied by the utility hydraulic pump.
38
What happens to the utility pump output pressure during engine start?
Increases from 3,000 psi to 4,000 psi ## Footnote This increase provides pressure to drive the starters.
39
What is the output pressure of the utility pump after the engine start switch is placed to OFF?
Returns to 3,000 psi ## Footnote The isolation valve then opens for subsystem operation.
40
What is the first step to start the engine in the described system?
Place ECL to stop ## Footnote This is followed by selecting fuel pumps on and the engine switch to motor.
41
What voltage is directed to the engine for starting?
28 VDC ## Footnote This comes from the emergency bus for engine no 1 or the DC ESS BUS for engine no 2.
42
What valve is opened to allow utility hydraulic system pressure to power the engine start motor?
Start valve ## Footnote This allows the engine to be cranked.
43
What happens to the isolation valve during engine start?
Closes ## Footnote This isolates subsystems and removes power to certain circuits.
44
What systems are powered down to reduce electrical load during engine start?
Left, right, center window icing circuits, cabin heater, blower circuits, avionics cooling fan, RH and LH aft fuel boost pumps ## Footnote These systems are powered down to minimize load during start.
45
What is the role of the cross-tie in the engine start system?
Prevents an engine from being started if the other engine start switch is not at the OFF position ## Footnote This ensures safe operation.
46
At what N1 speed should the ECL be advanced to the GROUND?
10-15% ## Footnote This is necessary to set the engine start switch to START.
47
What does advancing the ECL to the GROUND do during engine start?
Introduces start fuel to the combustion and activates the igniters ## Footnote This is crucial for engine ignition.
48
What is the initial step before starting the engine?
Place the engine start switch to MOTOR and allow the N1 speed to stabilize ## Footnote This step ensures the engine is ready for ignition.
49
At what percentage of N1 should the start switch be turned off?
50% N1 ## Footnote This action closes the start valve and reopens the utility system isolation valve.
50
What is the hook limit capacity?
28,000 lbs ## Footnote This limit is crucial for safe operation in lifting operations.
51
What components are included in the hook limit system?
* Hook actuating cylinder * Transfers beam * Solenoid-operated hydraulic control valve * Control relay * Cargo hook control panel ## Footnote These components work together for effective hook operation.
52
What is the function of the guarded upper hook release switch?
Locked on both cyclic grips ## Footnote This is a safety feature to prevent accidental release.
53
What provides power for the operation of the control circuit?
No. 2 DC BUS ## Footnote This power source is essential for the functioning of the hook control system.
54
What type of pressure is Chamber B charged with?
2100 psi ## Footnote This pressure is critical for the operation of the hook actuating mechanism.
55
What happens when the release valve is reenergized?
Utility hydraulic pressure is cut off to the system and ports No 1 and No 2 are open to return ## Footnote This allows for the proper functioning of the hook release mechanism.
56
What is the role of the floating piston in the hook assembly?
Closes the hook arm when air pressure acts on it ## Footnote The floating piston mechanism ensures the hook remains closed until released.
57
How is the hook opened from the cockpit?
Place the cargo hook master to arm and press the guarded upper hook release button ## Footnote This sequence activates the hook release mechanism.
58
What condition causes the hook to be locked closed?
Over center position of the latching cam linkage ## Footnote This design ensures safety by preventing accidental opening of the hook.
59
What should be done if the hook cannot be opened using standard methods?
Move emergency switch to release or pull the T-handle ## Footnote These are emergency procedures to ensure the hook can still be released.
60
What does the HOOK OPEN annunciator light indicate?
The hook is open ## Footnote This is a visual indicator for the pilot to confirm hook status.
61
What triggers the HOOK OPEN annunciator light?
* Movement of hook rotating cam * Movement of the hook actuating cylinder ## Footnote These movements activate micro switches that illuminate the light.
62
The hook actuating cylinder is described as what type of assembly?
Flogging piston assembly with a solenoid valve ## Footnote This assembly is essential for the precise control of the hook.
63
What is the purpose of Chamber C in the hook assembly?
Vent to atmosphere except when emergency hook release switch is operated ## Footnote This chamber helps in the normal operation of the hook assembly.
64
What happens when the switch is off in the hook release mechanism?
Opens the relay and allows the pressurized fluid to return ## Footnote This action ensures safety by closing the hook when not in use.

AW (7 decks)

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