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C-5 Eval Guide > Hydraulics > Flashcards

Hydraulics Flashcards

1
Q

What does the hydraulic system consist of?

A

 Two engine driven hydraulic pumps
 A hydraulically driven suction boost pump
 A hydraulic reservoir
 Power transfer units
 Two ATM pumps (supplies hydraulics for flight and ground ops)
 RAT pump (supplies #2 hydraulic pressure in event of total power failure)
 Electric suction boost pump

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2
Q

Where can you service the hydraulics in-flight?

A

 #3 service center through a selector valve, fluid receptacle and hand pump (right side cargo compartment)
 A ground fill connection in the right MLG fairing (external servicing)

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3
Q

How is the hydraulic fluid cooled?

A

 Each hydraulic system is equipped with a heat exchanger for fluid cooling.
 The heat exchangers for hydraulic systems No. 1 and No. 2 are installed in the No. 2 main fuel tank.
 The heat exchangers for hydraulic systems No. 3 and No. 4 are installed in the No. 3 main fuel tank.

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4
Q

Hydraulic fluid from the engine driven and ATM driven pumps case drain is drawn through the heat exchangers to maintain a temperature of:

A

130 - 150 F

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5
Q

How much fuel is required for hydraulic cooling?

A

18000 lbs (heat exchangers are only in tanks #2 and #3 and each tank must have at least 4500 lbs of fuel in it; to ensure balanced fuel tanks the #1 & #4 tanks must also have 4500 lbs thereby totaling 18000 lbs

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6
Q

How many engine driven Hydraulic pumps are installed on each engine?

A

2 (61 GPM, variable displacement)

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7
Q

What is the purpose of the hydraulic suction boost pump?

A

Prevents cavitation of the engine driven pumps by providing pressurized fluid from the unpressurized reservoir to engine-driven pumps

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8
Q

Where does the hydraulic suction boost pump get its operating pressure?

A

From the engine–driven pumps (top/bottom) which it supplies and will operate as long as there is hydraulic pressure supplied to the system

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9
Q

When and why are the electric suction boost pumps used for during engine start?

A

For engines 1 and 4 only, used for engine start, ground ops and takeoff & landing to pressurize the suction lines to engine driven pumps and ATMs.

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10
Q

Are the hydraulic reservoirs pressurized?

A

No

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11
Q

What is a PTU and how does it work?

A

 Power Transfer Unit
 It takes hydraulic pressure from one system and provides pressure to the adjacent system without mixing hydraulic fluid between systems. It is basically two constant displacement motors connected through an internal shaft.

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12
Q

When are the PTUs energized?

A

When demands are greatest; emergency ops, ground maintenance and takeoff/landing

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13
Q

What is an ATM?

A

Provided to supply hydraulic pressure to systems 1 & 4 during ground operation or for maintenance purposes and for emergency in-flight operation. The ATM pumps are 40-GPM pumps and are controlled by switches on the flight engineer console

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14
Q

How does the ATM provide hydraulic pressure?

A

It uses bleed air from an APU, an external source, or the main engines to drive the pump which provides the hydraulic pressure.

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15
Q

How many ATMs are installed on the C-5 and what hydraulic systems to they supply pressure to?

A

Two: Right ATM pressurizes system 4, Left pressurizes system 1.

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16
Q

What is the RAT and what is it used for?

A

 Ram Air Turbine
 A Ram Air Turbine (RAT) pump is provided to supply pressure to hydraulic system No. 2. The RAT provides capability for airplane control using limited flight controls for the time required to restart the engines or ATM pumps. It is deployed on the left side of the aircraft aft of the crew entrance door and forward of the main gear wheel well. The airstream drives the turbine and turns the hydraulic pump.

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17
Q

How is the RAT deployed?

A

 AUTO: In the AUTO position the RAT will automatically deploy in flight if both inboard and either outboard engine is shut down or falls below IDLE N2. The RAT in-flight mode is set when the strut pressure switches on either MLG No. 1 and No. 3, or MLG No. 2 and No. 4 are in the air position.
 MANUAL: RAT switch is placed to DEPLOY on Pilot Instrument Panel
OVERRIDE: A guarded emergency RAT deployment Override Pushbutton, located in the No. 2 hydraulic service center is used to deploy the RAT in the event the AUTO or DEPLOY positions of the Ram Air Turbine switch do not deploy the RAT.

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18
Q

Deploying the RAT de-energizes which PTU?

A

1-2 PTU

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19
Q

In the AUTO position inflight, the RAT will automatically deploy when:

A

The two inboard engines and either outboard engine are shut down or fall below IDLE N2.

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20
Q

The RAT’s AUTO position is energized through a combination of four pressure switches and is operable only when the airplane is __________

A

In flight

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21
Q

Will the RAT deploy in AUTO if you shut off all 4 engines in the chocks?

A

NO; The AUTO position is operable only when the airplane is in flight; 1 switch per bogie

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22
Q

Why do we place the RAT switch to RETRACT on engine shutdown considering that the strut pressure switch on the ground prevents the RAT from deploying when the engines are shutdown?

A

In case the aircraft is knelt, whereby overriding the WOW switch and causing the RAT to deploy on the ground when knelt.

23
Q

Where are the PTUs located?

A

 PTU 1-2: located between hyd 1 & 2 service centers, left forward gear pod
 PTU 2-3: located on wing rear beam, fwd of troop compartment
 PTU: 3-4: located between hyd 3 & 4 service centers, right forward gear pod

24
Q

What are the positions of the RAT switch?

A

RETRACT, AUTO & DEPLOY

25
Q

What powers the RAT to extend and what does it then do?

A

 Extends with #2 hydraulic power (if available) or a from a system pressurized accumulator (if system 2 is de-energized)
 Extends into the airstream and pressurizes the hydraulic suction boost pump (system #2) to prevent cavitation (powers emergency flight controls and emergency generator)

26
Q

Where are the Emergency RAT retraction and deployment override buttons?

A

2 hydraulic service center (near station 1133)

27
Q

What is the purpose of the RAT deployment override pushbutton?

A

To deploy the RAT in the event AUTO or DEPLOY positions of the RAT switch do not deploy the RAT

28
Q

What is the purpose of the PTU override buttons and where are they located?

A

To manually open the hydraulic shutoff valves on either side of a PTU. They are located in the hydraulic service centers and on the wing rear beam

29
Q

What is the PRESS LOW light?

A

The output of the respective engine-driven hydraulic pump, top or bottom, (8 total) falls below a set value

30
Q

What is BOOST PRESS LOW light?

A

On when respective hydraulic suction boost pump (4 total) pressure falls below a set value

31
Q

When does the RAT DEPLOY (red) light come on?

A

Illuminates when a RAT extend signal is sent from the VIAs through RIU No. 3.

32
Q

When does the RAT UNLOCKED Caution CWA come on?

A

When the RAT locking actuator is unlocked

33
Q

Which hydraulics power the flight controls?

A

 ELEVATORS: Inboard 2 & 3 | Outboard 1 & 3
 AILERONS: Left 1 & 2 | Right 2 & 4
 RUDDER: Upper 1 & 3 | Lower 2 & 3

34
Q

Prior to engine start, how will you start the engines if the #1 hydraulic boost pump is inoperative? Why?

A

 Alternate start sequence 4, 3, 2, 1
 In order to provide hydraulic pressure to the suction boost pump, either the electric boost pump must be operative or you must have hydraulic pressure from another source. Since #1 and #4 are the only engines with electric suction boost pumps, #4 must be started first if the #1 electric pump is inoperative.

35
Q

Climbout flight path performance planning assumes landing gear retraction is initiated ____seconds after liftoff and the landing gear is fully retracted _____ seconds after liftoff.

36
Q

With the loss of hydraulic systems No. 1 and No. 4, ensure that the MLG Emergency Extension accumulators are charged to _______ PSI prior to emergency extension of the gear.

37
Q

With the loss of #1 and #4 hydraulic systems, how do you get the MLG down?

A

MLG Emergency Extension accumulators (can be recharged in flight-hand pump)

38
Q

Extension may be accomplished at recommended airspeed ____KCAS, however the MLG may not rotate at airspeeds in excess of ____ KCAS.

39
Q

The MLG may fail to rotate to the down and locked green wheels position if emergency extension is accomplished at speeds in excess of ____ KCAS with hydraulic pressure available. The MLG will not rotate at speeds in excess of _____ KCAS using accumulator pressure only.

40
Q

What do you do if you lose the hydraulic-driven suction boost pump on #1 or #4? On #2 or #3?

A

 If #1 and #4 turn on the respective electric driven boost pump
 For #2 or #3, treat as a loss of hydraulic quantity

41
Q

What is hydraulic overpressure? What should you do for hydraulic overpressure?

A

 3400 psi
 If mission permits, shutdown the engine using the PESC
 If the mission does not permit engine shutdown, reduce power to a min on the affected engine, place the adjacent PTU switch on, depress one or both adjacent hydraulic pumps (as required) and monitor all systems for fluid loss. Lastly, check hydraulic reservoir temperature and if an overtemp of 225F or above is experienced, system contamination may develop (reconsider PESC)

42
Q

Are there any CAUTIONS with hydraulic system overpressure? What are they?

A

Do NOT depress the pump or pull the fire handle; you may damage the pump

43
Q

Inflight the #3 hydraulic system indicates 3300 psi. Would you shut the engine down for hydraulic overpressure?

A

No, but monitor in case it goes over 3400 psi; check direct reading gauge

44
Q

If both engine driven hyd pumps fail (top and bottom) on engine #1, what checklist do you call for?

A

Loss of hydraulic system No. 1 pressure checklist

45
Q

Both systems #1 and #2 lose quantity. What checklists will you call for?

A

 Loss of Hydraulic System #1 Quantity (3.77.7.1)
 Loss of Hydraulic System #2 Quantity (3.77.7.2)
 Loss of Hydraulic Systems #1 AND #2 Quantity (3.77.8.1)
 Dual Hydraulic Systems Inoperative Effects on Flight Controls (3.77.9)
 Review Three Hydraulic Systems Inoperative Effects on Flight Controls (3.77.10)
 If third system lost, Ailerons Inoperative, Additional Means of Roll Control (3.62.4)

46
Q

With the loss of #1 and #4 hydraulic systems, how do you get the NLG down?

A

CED accumulator (min pressure of 2500 psi is required); CED is powered by hyd system #4, hand pump is not accessible during flight – under the CED

47
Q

With the loss of #1 and #4 hydraulic systems, how do you get the flaps down?

A

You don’t; you must fly a no flap approach and landing

48
Q

What main systems are lost with loss of hyd sys #1 AND #4?

A

 Must land NO FLAP
 MLG must be extended using Emergency Extension accumulator
 NLG must be extended using CED accumulator
 Normal & Alternate brakes are inop  Emergency brakes only
 No anti-skid
 Rudder pedal & nosewheel steering inop
 No alternate pitch (Autopilot) trim
 Secondary climb & dive valves are inop (wing overpressure relief)

49
Q

Where do you find the hydraulic power distribution chart?

50
Q

What is the normal hydraulic pressure?

A

3000  150 psi (2850 – 3150)

51
Q

What are the operational RAT speeds?

A

 Max deploy – 350 KCAS / 0.825m
 Max retract – 180 KCAS / 0.45m
 Min for RAT to provide hyd pressure to drive Emer Gen AND Flight Controls (above 15,000 ft) – 190 KCAS
 Min for RAT to provide hyd pressure to drive Emer Gen AND Flight Controls (below 15,000 ft) – 175 KCAS
 Min for flight instruments connected to Emer AC, Iso AC & Avionics AC buses – 155 KCAS (all driven by Emer Gen)

52
Q

If the ATM PUMP PRESS light comes on with the ATM switch in OFF, you must ____________ (3.77.3) Why??

A

Immediately depress its respective hydraulic system; the ATM pump is spinning backwards without lubrication

53
Q

How many inoperative engine-driven hydraulic pumps are allowed? Any restrictions on this?

A

 Max of 2 (only 1 pump on 2 non-adjacent engines may be inop – B Base)
 All pumps shall have positive depress capability
 Adjacent PTUs must be operative

C-5 Eval Guide (17 decks)

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