only and require installation of the couplings andcontinuity wire.One end has a male coupling and the other endhas a swivel-type female coupling (fig. 5-13). Leakagebetween the couplings is prevented by an O-ring inthe female coupling. Both couplings are machined toreceive the nylon spiders that act as non-conductingsupports for connecting the continuity wire. The con-tinuity wire runs through the hose and is slightlylonger than the hose, to allow for hose stretching.New hoses and hoses that were out of service fora long time must be cured (pickled) before beingplaced in service. Use the following procedure:NOTESome new hoses manufactured according toMil-H-17902 do not require pickling. How-ever,they must still be flushed and tested prior touse.1. Flush the hose with 100 gallons of fuel.2. Cap one end and elevate the hose.3. Fill the hose, cap it and let it stand for at least1 week.4. Drain the hose and observe drainage fordiscoloration. (If discoloration is observed, repeatsteps 1 through 3.5. Test the fuel with the CFD. (Should be lessthan 10 mg/1.)6. Install the hose and flush until acceptable fuelis sampled. (Less than 2 mg/1.)Because of their environment, fuel hoses are sub-jected to severe wear and tear. They should be in-spected during each use for superficial cuts, wornareas or bubbles in the hose, deep cuts that exposethe wire reinforcement or inner layer wrapping, andleaky couplings.If any of the above is observed, notify the flightdeck supervisor, flight deck control, and flight deckrepair immediately.You can prolong the useful life of fuel hoses bynot twisting or kinking a hose, not rolling a twistedor kinked hose up on its reel, and not allowingaircraft, tractors. or other rolling stock to run overthe hoses. New fuel hoses are hydrostatically testedbefore being placed in-service, and in-service hosesare hydrostatically tested annually. In accordancewith PMS requirements, fuel hoses are tested at 1 1/2times their system operating pressure.If a hose is found to be damaged near an endcoupling but otherwise usable, it may be salvaged bycutting the damaged area off. This is known as “cut-ting back” a hose. To cut back a fuel hose, do thefollowing:1. Disconnect and remove the spiders and conti-nuity wire from the hose.2. Remove the coupling from the damaged end.a. Unscrew the external taper sleeve fromthe coupling end and slide it down past the damagedarea.Figure 5-13.—Fuel hose couplings.5-12
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