Inverness, MS, USA
N58377
Boeing Helicopters Div. 369D
The helicopter is configured with an external horizontal platform mounted adjacent to the left loading door, between the fuselage and the skids, for use during in-flight transfer of a lineman from aircraft to structure during inspections of high tension transmission line supports. The exact procedures for the in-flight lineman transfer call for the helicopter-to-structure static electricity grounding cable to be clamped to the structure prior to the actual transfer. By design, the ground cable clamping is the very first procedural task and the unclamping is the very last procedural task. When the pilot sees the cable and clamp returned to its holding pouch on the platform, that is his cue to back the helicopter away from the structure. In this particular occurrence, the procedural tasks got out of sequence, and when the pilot saw the ground cable and clamp in its pouch, he backed the rotorcraft away. The lineman, still tethered to the rotorcraft, was pulled off the structure, and the lineman's choice of safety tether attachment point on the rotorcraft gave way under his weight, causing the fatal fall.
On February 23, 2001, about 1300 central standard time, a Boeing 369D, N58377, registered to Helicopteros Atuneros, Inc., operated by Air #2, LLC, as a Title 14 CFR Part 133, power line tower inspection flight, suffered a lineman fall to his death near Inverness, Mississippi. Visual meteorological conditions prevailed and a visual flight rules flight plan was filed. The commercially rated helicopter pilot was not injured, and the rotorcraft was not damaged. The flight departed the Indianola Airport about 0800, and was staging out of a landing zone named LZ 397. The most recent departure of the helicopter was from LZ 397 at 1130. According to an FAA inspector, it was the company's procedure to in-flight transfer the safety tethered lineman from the helicopter's external platform to the powerline pole or structure using the same sequential procedure every time. The procedure was: (1) the lineman transfers the static discharge ground cable and clamp from a canvas pouch mounted on the helicopter platform to the pole or structure, (2) he unplugs his intercom, (3) he unfastens his lapbelt connected to the platform, (4) he transfers to the pole using his pole climbing spikes to hold his weight, (5) he transfers his safety harness fitting from the helicopter to the pole, (6) he stows the static discharge cable back into the pouch. When the pilot sees the static cable returned to the canvas pouch, that is his cue to back the helicopter away. Somehow the sequence got interrupted, the helicopter backed away while the lineman was still tethered to the aircraft, pulling him off the structure, and the tether attachment at the aircraft failed. Closer inspection by the FAA inspector revealed that the safety harness attachment designed for securing the tether to the helicopter was not as convenient as a platform mounting strut, and the lineman was using the strut instead. The strut did not withstand the swinging weight of the dislodged lineman, and parted, causing the fall.
The lineman's failure to use the designed attachment point for securing his safety harness to the helicopter, resulting in overload and failure of the component he did attach to. A factor in the accident was the lineman's failure to follow exact sequential procedures for performing the in-flight transfer from rotorcraft to structure, resulting in his being dragged off the structure by the retreating rotorcraft.
Source: NTSB Aviation Accident Database
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