Equipment Failure

On Feb. 24, 2014 an Outside Line contractor using a contract helicopter performing external human load work had an inadvertent hook release while a lineman was being transported on the long line, dropping him into the back-up secondary device (Belly band). There were no injuries and the pilot returned the lineman and the aircraft to the ground safely. An investigation into the release was conducted and the initial report indicated that the release was due to a jam nut on the manual hook release loosened, allowing the release cable to come out of adjustment, resulting in the hook release. Further investigation into the release revealed the slack in the cable used on this type of manual release was slightly long to allow for side operations and as a result allowed the swedged fitting on the end of the cable to protrude past the cradling point for the fitting. If the end of the swedge fitting rest on the outside of the contact point it removes all free play in the cable and therefore there is no free play in the release mechanism which would allow the hook to open with very little effort, such as strain on the cable. Inspection of the cable is also very important due to the fact that the cable is a wearable item and must be replaced at any sign of damage, such as broken strands or kinks in the cable.