the stop allows for this structural stretch, whichcauses a progressive narrowing of the gap distancebetween the crosshead and crosshead stop. Afterthe purchase cable has been stretched and reachesthe minimum allowable clearance of 1 inch betweenthe crosshead and crossheaddimension is used thereafter.NOTEstop,a 7-inchThese dimensions are applicable to theMod 2 arresting engine.The Mod 3clearances are different. Mod 3 clearancesare as follows: On newly reeved engines a7-inch clearance is set up between thecrosshead and crosshead stop. After thenew cable stretches to the minimumallowable distance between the crossheadand the crosshead stop, crop and repour anew terminal and set the crosshead adistance of 6 inches from the crosshead stop.When it becomes necessary to rereeve asingle-reeved engine, both purchase cables must bereplaced. Reeving only one purchase cable on asingle-reeved engine results in unequal length of thetwo cables, because of the initial stretch of the newcable. An offcenter deck pendant is an indication ofone cable stretching more than the other. Thiscondition could cause one of the purchase cableterminals to rest in the deck sheave. To correct thiscondition, you will have to crop the longer cable andrepour the terminal.During arrestment operations, torque builds upin the purchase cables. Failure to remove thistorque results in accelerated wear and bird-caging ofthe cables, with vastly increased susceptibility tofailure.Compliance to detorquing methods atspecified internals is mandatory. Newly installedpurchase cables should be detorqued after the initial50 landings (no more than 60) and every 200landings thereafter.WARNINGKeep hands free of spinning parts whenreleasing torque from cables.Purchase cable torque can be removed in thefollowing ways. During flight operations, disconnectone side of the crossdeck pendant at the completionof an arrestment and partially retract the engine.This allows the cables to untwist. If time allows,blow the engine down to 200 psi and pull the engineout to its full stroke; disconnect one side of thecrossdeck pendant; and retract the engine slowly toapproximately 20 feet out of battery.NOTEIf torque buildup is greater than normal,it is recommended that the crossdeckpendant be disconnected from both topsideterminals to allow a more efficient detorqueof the cable system.As shown in figure 3-45, stored torque isremoved at the anchored end of the purchase cableby removing the quick-release pin from the couplinglock lever and striking the lock lever with a hammer.This allows the purchase cable to spin and releasethe torque.Figure 3-45.—Releasing torque from cables.3-50
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