History of Flight
On March 14, 2017, at 1546 eastern daylight time, an MD Helicopters 369FF, registration N530KD, impacted terrain during a power line construction flight near Chalmers, Indiana. The commercial pilot was fatally injured, and the helicopter was destroyed. The helicopter was registered to a private individual and operated by Rogers Helicopters, Inc., under 14 CFR Part 133 as an external load operation. Visual meteorological conditions prevailed, and no flight plan was filed. The helicopter departed from a staging area near the accident site about 1530.
The purpose of the flight was to thread a braided metal sock line through a tower structure and pull it to the next tower. The helicopter was equipped with a side pull hook assembly attached to the left cabin step. A 50-ft blue nylon long line with a protective sheath was attached to the cargo hook, and a grappling hook was connected to a metal needle. The pilot used the needle to thread the sock line by hooking it to the tower, releasing the grappling hook, moving the line to the opposite side, and picking up the needle with the grappling hook.
Tension on the sock line was controlled by a triple drum puller located about 2 miles north, operated by a power line construction employee who communicated with the pilot via radio. The pilot had threaded the sock line through nine towers and was approaching the tenth when the accident occurred. The amount of brake applied was not determined.
A witness provided a 3-minute cell phone video showing the accident sequence. The pilot attempted twice to hook the needle to the tower unsuccessfully. Before the third attempt, the helicopter wobbled several times. On the third attempt, the helicopter flew backward until the needle impacted the tower. The helicopter continued backward, pitched up, and descended with the tailboom pointed at the ground. The needle's aft loop separated from the needle. The helicopter made a descending 180° clockwise rotation, stopped facing north, then rolled left about 80°. The long line became entangled with the main rotor blades, which then impacted the cabin and tailboom. The tailboom separated, and both sections descended and impacted the ground. There was no post-crash fire.
Personnel Information
The pilot's personal logbooks were not found. A review of his FAA medical certificate application indicated that, as of October 12, 2016, he had accumulated 14,975 hours of flight experience, all in rotorcraft. Company duty log sheets showed he flew 336.7 hours in 2016 and 12.8 hours in 2017.
Aircraft Information
The helicopter was equipped with a Colorado Helicopters, Inc., Side Pull Hook Assembly per STC SH5230NM, designed to quickly rig for pulling a sock line. It featured mechanical and electric cargo hook release mechanisms, certified for a maximum side pull load of 1,900 lbs. The system included a breakaway swivel with a calibrated shear pin designed to break if overloaded.
The needle frame was steel tubing with forward and aft sections connected by a hinge bracket. Each section had a closed loop with a straight open hook extending aft for attaching to tower cross-members. The aft end connected to the sock line via metal carabiners and a non-breakaway swivel. The needle weighed about 200 lbs.
Meteorological Information
Weather conditions from video and witness statements included an overcast cloud layer, light and intermittent snow, and wind gusts of unknown speeds. One witness felt a gust of wind at the time of the accident.
Wreckage and Impact Information
The fuselage came to rest on its left side. The tailboom aft section was about 5 ft north of the fuselage. Main rotor blades separated and lay south of the fuselage. The tailboom had blue transfer marks, and the long line sheath was entangled in the tail rotor assembly. The horizontal and vertical stabilizers separated. The lower portion of the long line was entangled in the main rotor hub and extended over the right side. The grappling hook remained attached to the line and was partially embedded in soil.
The long line separated in tension overload near the top, a few feet from the cargo hook. The cargo hook was found open. The breakaway swivel, its shear pin, two carabiners, and the upper portion of the long line were not found. The needle's fractured aft loop was found about 50 yards south. Postaccident testing confirmed mechanical and electrical continuity to the cargo hook.
Examination of the trim switch and wiring revealed fractures but no preimpact anomalies. CT scan of the trim system showed no anomalies. Multiple postaccident examinations found no mechanical malfunctions or failures with the engine or airframe that would have precluded normal operation.
Medical and Pathological Information
An autopsy determined the cause of death as blunt force trauma. Toxicology testing revealed no drugs or other substances.
Tests and Research
Portions of the needle assembly were examined at the NTSB Materials Laboratory. The aft closed loop fractured at two locations due to ductile-bending overstress, with no evidence of preexisting cracks. The load required to fracture the 1-inch solid round bar was calculated to be 73,790 lbs., nearly 40 times greater than the load required to break the side hook's breakaway swivel shear pin.
A video study estimated that the maximum force applied by the long line before the helicopter became tethered to the tower was 875 ±130 lbs. The study showed that shortly before needle contact, the helicopter moved backward with a yaw angle of about 45° relative to the tower. The needle rotated to a horizontal orientation, contacted the tower, and became entangled. The long line remained attached; the breakaway swivel did not appear to separate before the line became entangled in the rotor blades.