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CHAPTER 2. EQUIPMENT AND OPERATION SAFETY ISSUES GRAPPLE HOOK DEPLOYMENT. A crucial event during banner tow operations is the deployment of the grapple hook. The grapple hook should be released in such a manner that it, or the grapple line, does not snarl in aircraft control surfaces or landing gear, to include the tailwheel, in conventional gear configurations. The hook line must be observed to have clearance before every low approach. If the grapple line becomes snarled on the tailwheel or a control surface, a reduction in the capability of the pilot to control the airplane may occur. In a worst case scenario, movement of the rudder or elevator control surface may be limited or even jammed. Further, the pilot may not be able to release the grapple line because of the entanglement. The best cure is prevention. PREVENTION OF GRAPPLE LINE ENTANGLEMENT. Depending upon aircraft configuration, several devices can be used to help avoid entanglement. The tow hitch end of the grapple line can be stiffened to prevent it from looping around the tailwheel or the empennage as the line is deployed. Stiffening of the line may be accomplished by working a 2-foot length of stiff plastic garden hose over the line. The hose is then carefully heat formed over the knots at the ring. See Figure 2-1, Examples of a Plastic Garden Hose Installation.  Devices, such as spring keepers, can be used to hold the grapple line away from the tailwheel or the tail control surfaces until the grapple line is released. The spring keeper is attached to the bottom of the horizontal stabilizer or the empennage bracing wire into which the grapple line is connected. The configuration of some aircraft may not permit the use of keepers to hold the grapple line away from the airframe. As an alternate method, the use of a rudder guard or Vee bar (if a multiple rope system is used), may be helpful. This device is attached to the aft fuselage and serves to guide the grapple line away from the tailwheel or control surface horns during deployment. See Figure 2-2, Examples of a Vee Bar.  The pilot should avoid uncoordinated or abrupt maneuvers during grapple line deployment. Trained ground support personnel should be available during banner pickup operations, and be briefed to observe the aircraft and inform the pilot if the line appears to be trailing abnormally. Picking up a banner with a loosely, snarled line will only tighten it and complicate the problem. |
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