maintenance practice.doc

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CONTENTS PAGES

INTRODUCTION. . . . . . . . . . . . . . . . . . . .

. . . <1>

-AIRCRAFT REFUELING. . . . . . . . . . . . . . . . . .

1.1

- AIRCRAFT DEFUELING. . . . . . . . . . . . . . . . .1.2

PROJECT. . . . . . . . . . . . . . . . . . . . . . . . .

. . . . <2>

GENERAL PROCESS. . . . . . . . . . . . . . . . . . . . .

2.1

- REFUELING

PROCESS . . . . . . . . . . . . . . . . . . . 2.2



-REFUELING SIGNALS . . . . . . . . . . . . . . . . . . .

2.3

-AIR-FLIGHT REFUELING. . . . . . . . . . . . . . . . .2.4

-DEFUELING PROCESS. . . . . . . . . . . . . . . . . . .

2.5

-SAFETY REQUIREMENT

(REFUELING/DEFUELING) . . . . . . . . . . . . . . . .2.6

CONCLUSION. . . . . . . . . . . . . . . . . . . . . .

. . . . <3>

REFERENCES . . . . . . . . . . . . . . . . . . . . . .

. . . . <4>

AIRCRAF T REFUELING

To supply an aircraft with more fuel.The plane has to be refueled everythousand miles.The plane need stopped at certain time and condition to be

refuel.

For the military aircraft,there are several types of refuel :

a. Open-Port Refueling.



Open-port refueling is refueling by inserting an automotive-type nozzle

into a fill port of larger diameter. Because the port is larger than the

nozzle, fuel vapors can escape through the fill port during open-port

refueling operations.Airborne dust and dirt, as well as rain, snow, and ice

can get into the fill port during refueling. Spills can also be caused by the

sudden pressure surge that comes when pumping from another nozzle in the

system is completed, throwing the whole pressure of the pump to the

operating nozzle.

b. Open-Port Hot Refueling .

In combat operations, this operation may be used for helicopters when

the requirements of the tactical mission and the benefits of

reducing ground time outweigh the inherent risks of this method of refueling.

In noncombat situations, helicopters may be refueled by this method

when there are compelling reasons to do so.

c. Rapid Hot Refueling.

Aircraft may be rapid (hot) refueled (with engines running), electrical

power on, radios on, weapons system on with safety covers/guards/switches in safe position, and with any computer systems

operating that would require reprogramming if shut down.

Fuel Truck Operations.

The M49A2C tank truck with a 1,200 gallon stainless steel tank, the M559

tank truck with a 2,500 gallon stainless steel tank, and the M857 semitrailer

with a 5,000 gallon tank are used to fuel Army aircraft



Vacuum assist defueling systems can evacuate airplane fuel tanks in a

fraction of the time normally allocated to a gravity system. Nevertheless,

many vacuum assist systems are useful only with specific fuel drain

configurations.

Thus, the use of such vacuum assist systems is limited to certain aircraft andcertain personnel trained to match an inventory of attachments with the

design requirements of fuel drain systems of particular aircraft.

REFUELING PROCESS

After the aircraft parks and its engine or engines are shut down, the

rotor blades are secured, and armaments are set on SAFE, thesequence of the refueling operation can start.

(a) Check the interior of the aircraft. No one should be aboard

during refueling unless the pilot or copilot are on board to monitor the

quantity of fuel to be loaded



(b) Drive the tank vehicle into position in front of the aircraft.

Do not drive the refueler directly at the aircraft because brake failure

could cause a serious accident.

(c) Keep a distance of at least 10 feet between the refueler and

the aircraft. There must be at least 10 feet between the refueler and

rotor blades of a helicopter. Keep a distance of at least 20 feet

between the exhaust pipe of the pump engine (or truck engine) and

the aircraft fill port and tank vent as shown in figure.Figure:Fuel Truck BackingApproach

Figure:At some airports,underground fuel pipes allowrefuelling without the need fortank trucks. Trucks just carry thenecessary hoses and pressureapparatus, but no fuel.

Figure:Refueler andhelicopter



(d) Park the refueler so that it has a clear and open path to

drive away from the aircraft in an emer- gency. Do not detach a tank

semitrailer from its tractor when refueling an aircraft; the tractor must

be ready to pull the trailer away from the aircraft if the need arises.

(e) Stop the refueler engine (unless it pow- ers the pump)and set the brake. Chock the tires of the refueler and of the aircraft if

appropriate.

(f) Check the fuel in the tank to make sure it is the righttype for the aircraft. Check the sight glass of the filter/separator tomake sure all water has been drained out.

(g) Place the truck fire extinguisher by the pump. Place afire extinguisher provided at the refueling point by the aircraft fillport.

(h) Unreel the ground cable and attach its ground-rod clip tothe nearest ground rod. If refueling where no ground rod isinstalled, drive the refueler ground rod into the earth tothe required depth and attach the clip to the rod.

(i) Ground the aircraft by attaching one end of a ground cableto the ground rod (either the rod that grounds the refueler or aseparate ground rod) and the other end to a bare metal part of theaircraft.

(j) Bond the nozzle to the aircraft before taking the dustcap off the nozzle and the cap off the fill port. If the aircraft has a

receiver for the bond plug, use the plug, if not, clip the alligatorclip to a bare metal part of the aircraft.



(k) Open the aircraft fill port and remove the nozzledust cap.

(l) Refuel into the oil tank.(m) Replace the cap on the fill port and then replace the

nozzle dust cap before disconnecting the nozzle bond.

(n) Remove the nozzle bond plug or undo the alligatorclip.Reel up the hose and nozzle.Do not drag the nozzle across theground.

(o) Undo the clip that grounds the aircraft Replace thefire extinguisher used at the nozzle.

(p) Release the clip on the ground rod and reel up thegrounding cable.

Do not drag the cable clips across the ground. If the refuelingoperation is over and the refueler ground rod was used, pull the rod upand stow it in the refueler. Replace the fire extinguisher in the refueler

Figure:Aircraft refueling &bonding



REFEULING SIGNALS



AIR-FLIGHT REFEULING

Air refueling systems permit complete in-flight or on the ground refueling of the aircraft fuel system.

1. With the engines operating or external electrical and hydraulic powerapplied, the probe is extended by placing the refueling probe switch inthe EXTEND position.

2. This electrically actuates the solenoid selector valve to supplyrestricted hydraulic flow to the extend port of the probe-actuatingcylinder.

3. The restrictor valves control the rate of cylinder extension andretraction. The check valve prevents pressure surges in the hydraulicreturn system from unlocking the probe-actuating cylinder during

flight.

4. After disengaging the probe nozzle from the tanker drogue, hold the airrefueling switch in RETRACT to actuate the solenoid selector valve tosupply pressure to the retract port of the probe actuating cylinder,causing it to retract and lock the probe into place.



5. A cockpit advisory panel transit light goes out whenever the probe is

locked in the extended or retracted position.

6. A probe floodlight, which illuminates the probe tip for visual contactwith the refueling drogue at night, is on whenever the refueling probeswitch is in EXTEND and exterior lights are on.

7. The floodlight goes out when the refueling probe switch is placed inRETRACT or OFF.

8. Organizational maintenance of the air refueling probe system normallyconsists of operational checks, troubleshooting, rigging and adjusting,and removal and installation of components.

9. To perform an operational check of the air refueling probe system, thehydraulic system must be pressurized to 3,000 psi, external electricalpower applied, and the in-flight refueling circuit breaker engaged.

10. Before actuating the system, ensure that all personnel andequipment are clear of the area of probe travel. The extension cyclerotates the probe from its stored locked position to an extend lockedposition.



11. Position the fuel probe switch to EXTEND. Check for proper probeextension and probe locking. If operation of the probe is not smooth,check for air in the system.

12. Position the fuel probe switch to RETRACT and check for properprobe retraction.

13. The complete extension cycle should be from 5 to 7 seconds,with the retraction cycle taking from 9 to 11 seconds.

14. Troubleshooting of the system should include a thoroughknowledge of the malfunction compared to proper system operationand referral to system schematics and troubleshooting tables providedin the MIM.

15. System rigging, component removal and installation, and allother maintenance should be in accordance with the procedures andsafety precautions outlined in the MIM.

DEFUELING PROCESS



Aircraft defuelings are to be performed in the following sequence:

1. Prior to starting the defuel operation, take samples of the fuel to be

defueled from the aircraft’s drains and visually inspect them for

contamination (qualified squadron personnel under the observation of

the driver/operator).

2. Determine the status of the fuel, that is, suspect or nonsuspect (defuel

truck operator). The person requesting the defueling operation will

confirm that the fuel is or is not suspect. Fuel is considered suspect if the

aircraft has malfunctioned and the fuel is believed to have contributed

to the problem or the fuel is thought to be of the wrong type.

3. Determine the amount of fuel to be removed from the aircraft (defuel

truck operator). Again, the squadron personnel requesting the defueling

operation will provide this estimate as part of the official request.

4. Select the defueling equipment to be used, that is, defueler for suspect

product or refueler/defueler for nonsuspect fuel (FMO and station

operator). Always check the remaining capacity of the defueler or refu-

eler/defueler to make sure there is adequate room to hold the fuel being

defueled. In addition, remember that sufficient fuel must be in the defueling

tank to maintain a flooded suction above the anti-vortex splash plate.

5. Position the defueler (defuel truck operator).

6. Verify that the aircraft is spotted properly (all personnel).

7. Check for possible sources of ignition (all personnel).

8. Verify that the defueling request chit corre- sponds to the instructions

from the dispatcher (defuel truck operator).

9. Connect the bonding wire from the defueler to the aircraft (defuel truck

operator).



10. Unload, position, and connect the defuel hose to the aircraft and the

defueling stub on the defueler (plane captain).

11. Start defueling upon signal from the nozzle operator (defuel truck

operator).

12. Adjust the valve downstream of the pump to optimize the defuel rate.

Maximum defuel rate gpm (defuel truck operator). When nearing

completion of the defuel process, very close attention should be paid to the

defuel rate to prevent pump cavitation and/or loss of prime. Discontinue

defueling of an aircraft if pump cavitation is a persistent problem.

13. Upon completion of the defuel operation, se- cure all equipment and

CHECK THE AREA FOR FOD (all personnel).

Figure 1Aircraft Defueling Certificate



SAFETY REQUIREMENT

Gasoline is Dangerous– Gasoline and fuel oils are designed to cause an explosion, preferably in

the engine– Fuel Spills can be dangerous, in addition to being an environmental issue– Fuel fumes can cause nausea

Refuel/Defuel Safely– Always concentrate on the task at hand– NEVER smoke while refueling– Don’t refuel/refuel near any open flames– Always turn off the engine– Make sure the fire extinguisher is within reach– Be sure to chock the wheels if you feel the equipment may roll– Don’t overfill the fuel tank– On hot days allow for the fuel to expand

Refueling/Defueling Areas– Be sure the area is clearly marked– Always clean up all spills as quickly as possible– Keep an extinguisher close– Make sure that all garbage is picked up and that equipment can easily

enter and leave the area

CONCLUSION

Servicing aircraft with fuel and defueling aircraft requires the utmostprecaution due to the highly flammable characteristics of fuel.

Personnel performing fueling and defueling operations must be thoroughly

maintenance manual. Personnel must also be completely familiar with the

aircraft being serviced. All the procedure should be adhered to at all times.



REFERENCES

1. CAIP PART 2

2. http://www.tpub.com/content/aviation

3.http://www.easternsupplies.co.uk

4.www.flight-wood.com

5.http://commons.wikimedia.org/wiki/Aerial_refu

eling

6.New Zealand Qualifications Authority 2006

http://www.easternsupplies.co.uk/

http://www.flight-wood.com/

http://commons.wikimedia.org/wiki/Aerial_refueling


http://www.easternsupplies.co.uk/

http://www.flight-wood.com/



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