SPYDER HYDRAULICS

What does the hydraulic system consist of? (1.9.1, 1.9.2.2) (p 1-128)

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 pumps

Where can you service the hydraulics in-flight? On the ground? (1.9.1.1) (p 1-128)

In-flight: #3 service center through a selector valve, fluid receptacle and hand pump (right side cargo compartment)

Ground: A ground fill connection in the right MLG fairing (external servicing)

How is the hydraulic fluid cooled? (1.9.1.2) (p 1-128)

Each hydraulic system is equipped with a heat exchanger for fluid cooling. Temp is kept between 130 and 150F.

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.

How many engine driven Hydraulic pumps are installed on each engine? (1.9.1.3) (p 1-128)

2, one top, one bottom pump per engine (61 GPM, variable displacement)

What is the required normal hydraulic pressure from the engine-driven pumps? (1.9.1.3) (p 1-128)

3000 psi

What is the purpose of the hydraulic suction boost pump? (1.9.1.4) (p 1-128)

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

Where does the hydraulic suction boost pump get its operating pressure? (1.9.1.4) (p 1-128)

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

When and why are the electric suction boost pumps used for during engine start? (1.9.1.4) (p 1-128)

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. They are also used any time a hydraulically driven boost pump fails.

Are the hydraulic reservoirs pressurized? (1.9.1.5) (p 1-128)

No

What is a PTU and how does it work? (1.9.1.6) (p 1-129)

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 together by a common shaft.

When are the PTUs energized? (1.9.1.6) (p 1-129)

Takeoff and landing when demands are greatest and also emergency ops and ground maintenance.

How many ATMs are installed on the C-5 and what hydraulic systems to they supply pressure to? (1.9.1.7) (p 1-129)

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

Deploying the RAT de-energizes which PTU? (1.9.1.8) (p 1-129)

1-2 PTU

What is the RAT and what is it used for? (1.9.1.8) (p 1-129)

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.

How is the RAT deployed? (1.9.2.3 & 1.9.2.4) (p 1-130)

AUTO: In AUTO position the RAT will automatically deploy inflight if both inboard and either outboard engine is shut down or falls below IDLE N2.

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.

The RAT's AUTO position is energized through a combination of four pressure switches (one per bogie) and is operable only when the airplane is (BLANK) (1.9.2.3) (p 1-130)

In flight

Will the RAT deploy in AUTO if you shut off all 4 engines in the chocks? (1.9.2.3) (p 1-130)

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

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? (1.9.2.3) (p 1-130)

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

What are the positions of the RAT switch? (1.9.2.3) (p 1-129, 1-130)

RETRACT, AUTO & DEPLOY

What powers the RAT to extend and what does it then do? (1.9.2.3 & 1.9.1.8)

Extends with #2 hydraulic power (if available) or 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)

Where are the Emergency RAT retraction and deployment override buttons? (1.9.2.4) (p 1-130)

#2 hydraulic service center (near station 1133)

What is the purpose of the RAT deployment override pushbutton? (1.9.2.4) (p 1-130)

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

What is purpose of PTU override buttons & where are they located? (1.9.2.7) (p 1-131)

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 (2-3 PTU).

When does the DEPLOY RAT (red) light come on? (1.9.3.7) (p 1-132)

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

When does the RAT UNLOCKED Caution CWA come on? (1.9.3.8) (p 1-132)

When the RAT locking actuator is unlocked

Where are the PTUs located? (Figure 1-44) (p 1-133)

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 fwd gear pod

What is an ATM? (1.10) (p 1-138)

An auxiliary hydraulic power source (systems 1 & 4) for use during ground operation and for emergency in-flight operation. The ATM pumps are 40-GPM pumps and are controlled by switches on the flight engineer console

How does the ATM provide hydraulic pressure? (1.10) (p 1-138)

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

Which hydraulics power the flight controls? (pg 1-23, Figure 1-12)

ELEVATORS: Inboard 2 & 3 | Outboard 1 & 3

AILERONS: Left 1 & 2 | Right 2 & 4

RUDDER: Upper 1 & 3 | Lower 2 & 3

Prior to engine start, how will you start the engines if the #1 hydraulic boost pump is inoperative? Why? (2.10) (p 2-104)

Alternate start sequence 4, 3, 2, 1

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.

How much fuel is required for hydraulic cooling? (-1: 2.53.1 & 11-2C5V3, 11.5.1)

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)

What do you do if you lose the hydraulic-driven boost pump on #1 or #4? On #2 or #3? (3.77.2) (p 3-283)

If #1 and #4 turn on the respective electric driven boost pump

For #2 or #3, treat as a loss of hydraulic quantity

If the ATM PUMP PRESS light comes on with the ATM switch in OFF, you must (BLANK) (3.77.3) (p 3-283) Why??

Immediately depress its respective hydraulic system; the ATM pump is spinning backwards without lubrication; refer to Loss of Individual Hydraulic System Quantity

What is hydraulic overpressure? What should you do for hydraulic overpressure? (3.77.5) (p 3-284)

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 hyd pumps (as required) and monitor all systems for fluid loss. Lastly, check hydraulic reservoir temp and if 225F or above is experienced, system contamination may develop from fluid breakdown (reconsider PESC)

Are there any special considerations or "cautions" with hydraulic system overpressure? What are they? (3.77.5) (p 3-284)

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

Inflight the #3 hydraulic system indicates 3300 psi. Would you shut the engine down for hydraulic overpressure? (3.77.5) (p 3-284)

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

If both engine driven hyd pumps fail (top and bottom) on engine #1, what checklist do you call for? (3.77.6) (p 3-284)

Loss of hydraulic system No. 1 pressure checklist

With the loss of #1 and #4 hydraulic systems quantity, how do you get the NLG down? (3.77.8.4) (p 3-288)

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

Both systems #1 and #2 lose quantity. What checklists will you call for? (3.77.8, p 3-289)

Loss of Multiple Hydraulic System Quantity (3.77.8)

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 & Figure 3-25)

Review Three Hydraulic Systems Inoperative Effects on Flight Controls (3.77.10)

With the loss of #1 and #4 hydraulic systems quantity, how do you get the flaps down? (3.77.9, Figure Growth 3-25) (p 3-290)

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

What main systems are lost with loss of hyd sys #1 AND #4? (3.77.9, Figures 3-25 & 3-26) (p 3-290, 3-293, 3-294)

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)

All ground spoilers inoperative

Where do you find the hydraulic power distribution chart? (Figure 3-26) (p 3-293, 3-294)

Section 3

What is the normal hydraulic pressure? (pg 5-3, Figure 5-1, Sheet 2)

3000 ± 150 psi (2850 - 3150)

What are the operational RAT speeds? (-1: Figure 5-13, p 5-29 & 3.23, p 3-66.2)

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)

How many inoperative engine-driven hydraulic pumps are allowed? Any restrictions on this? (112C5V3, Ch 3, Table 3.3, pg 27)

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