N530KD

HISTORY OF FLIGHTOn March 14, 2017, at 1546 eastern daylight time, an MD Helicopters 369FF, 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 the provisions of Title 14 Code of Federal Regulations Part 133 as an external load operation. Visual meteorological conditions prevailed at the time of the accident, and no flight plan had been filed. The helicopter departed from a staging area near the accident site about 1530 for the local flight.

The purpose of the flight was to thread a braided metal sock line through the center of a tower structure and pull the sock line to the next tower. The helicopter was equipped with a side pull hook assembly that attached the cargo hook to the left cabin step position on the helicopter. A 50-ft blue nylon long line with a protective sheath was attached to the cargo hook, and a grappling hook was attached to the other end of the long line. The grappling hook was connected to a large metal needle that enabled the pilot to thread the sock line through the tower structure. The needle was equipped with two hooks that were used to attach it to the tower structure. To thread the sock line, the pilot hooked the needle to the tower, released the grappling hook, moved the long line to the opposite side of the tower, and picked up the needle with the grappling hook.

The tension on the sock line was controlled by a triple drum puller located about 2 miles (and 10 towers) north. Each of the three drums contained sock line for one of the three phases of the tower as seen in figure 1. The puller featured a manual brake that was operated by a power line construction employee. The employee and the pilot communicated via radio as the pilot would announce his operational intentions. The employee stated that the pilot had threaded the sock line through nine towers. The pilot announced over the radio that he was slowing and approaching the tenth tower. The employee later heard yelling over the radio and then silence. The amount of brake applied on the sock line at the time of the accident was not determined.

A witness provided a 3-minute cell phone video of the events leading to the accident and the entire accident sequence. The video revealed that the pilot was attempting to attach the needle's forward hook to the tower structure (figure 1) when the accident occurred.

Figure 1 – Image from Accident Video with Notations

Review of the video showed that the pilot attempted twice to hook the needle to the tower and was unsuccessful each time. 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 a backward motion, pitched up, then descended with the tailboom pointed at the ground (figure 2). The needle's aft loop, which the grappling hook was attached to, separated from the needle and was thrown to the south. While still airborne, the helicopter made a descending 180° clockwise rotation, as viewed from above, with the long line still attached. The rotation stopped as the helicopter faced north then rolled left about 80°. The long line became entangled with the main rotor blades, and then the blades impacted the top of the cabin and the tailboom. The tailboom separated about mid span, and both the tailboom and the rest of the helicopter descended and impacted the ground. There was no evidence of a post-crash fire.

Figure 2 – Image from Accident Video with Notations PERSONNEL INFORMATIONThe pilot's personal logbooks were not found during the investigation. A review of the pilot's Federal Aviation Administration (FAA) medical certificate application indicated that, as of October 12, 2016, the pilot had accumulated 14,975 hours of flight experience, all of which were in rotorcraft. The company duty log sheets revealed that the pilot flew 336.7 hours in 2016 and 12.8 hours in 2017. AIRCRAFT INFORMATIONSide Pull Hook Assembly

The helicopter was equipped with a Colorado Helicopters, Inc., Side Pull Hook Assembly (figure 3) per supplemental type certificate (STC) SH5230NM. According to the STC holder, the purpose of the assembly is to quickly rig a helicopter for pulling a sock line on power line construction projects. The assembly featured mechanical and electric cargo hook release mechanisms. The system is certified for a maximum side pull load of 1,900 lbs., which is safeguarded by a breakaway swivel; the two-piece breakaway swivel is held together with a calibrated shear pin. The STC holder noted that if the airframe is about to be overloaded, the shear pin is designed to break and allow for the long line to fall away from the helicopter; no unusual attitudes will result, and the helicopter should easily come to a hover.

Figure 3 – Side Pull Hook Assembly

Needle

The frame of the needle was made of steel tubing; the forward and aft sections of the needle were connected in the middle by a hinge bracket. Each section of the needle featured a closed loop with a straight open hook extending aft; the straight hooks (see figure 4) allowed the pilot to temporarily attach the needle to a horizontal cross-member of the tower and then reposition the helicopter. The aft end of the needle was connected to the metal sock line via metal carabiners and a non-breakaway swivel. The weight of the needle was about 200 lbs. Figure 4 shows the multicolored needle connected to the long line via the grappling hook. The photo depicted in figure 4 was captured a few minutes before the accident and is indicative of the exact configuration during the accident sequence.

Figure 4 – Needle with Notations METEOROLOGICAL INFORMATIONEvidence from the accident video and witness statements revealed that the weather conditions consisted of an overcast cloud layer, light and intermittent snow, and wind gusts of unknown speeds reported by witnesses.

One witness reported that he was sitting in his truck facing west at the intersection of the adjacent county roads. His windows were down, and he felt a gust of wind at the time of the accident. AIRPORT INFORMATIONSide Pull Hook Assembly

The helicopter was equipped with a Colorado Helicopters, Inc., Side Pull Hook Assembly (figure 3) per supplemental type certificate (STC) SH5230NM. According to the STC holder, the purpose of the assembly is to quickly rig a helicopter for pulling a sock line on power line construction projects. The assembly featured mechanical and electric cargo hook release mechanisms. The system is certified for a maximum side pull load of 1,900 lbs., which is safeguarded by a breakaway swivel; the two-piece breakaway swivel is held together with a calibrated shear pin. The STC holder noted that if the airframe is about to be overloaded, the shear pin is designed to break and allow for the long line to fall away from the helicopter; no unusual attitudes will result, and the helicopter should easily come to a hover.

Figure 3 – Side Pull Hook Assembly

Needle

The frame of the needle was made of steel tubing; the forward and aft sections of the needle were connected in the middle by a hinge bracket. Each section of the needle featured a closed loop with a straight open hook extending aft; the straight hooks (see figure 4) allowed the pilot to temporarily attach the needle to a horizontal cross-member of the tower and then reposition the helicopter. The aft end of the needle was connected to the metal sock line via metal carabiners and a non-breakaway swivel. The weight of the needle was about 200 lbs. Figure 4 shows the multicolored needle connected to the long line via the grappling hook. The photo depicted in figure 4 was captured a few minutes before the accident and is indicative of the exact configuration during the accident sequence.

Figure 4 – Needle with Notations WRECKAGE AND IMPACT INFORMATIONThe helicopter's fuselage came to rest on its left side (figure 5), the same side as the pilot's seat. The aft section of the tailboom came to rest about 5 ft to the north of the fuselage. The main rotor blades separated from the rotor hub and came to rest to the south of the fuselage. The tailboom exhibited blue transfer marks, and the long line sheath was entangled in the tail rotor assembly. The horizontal and vertical stabilizers separated from the end of the tailboom. The lower portion of the blue long line was entangled in the main rotor hub and extended over the right side of the fuselage and right skid toward the tailboom. The grappling hook remained attached to the long line and was partially embedded in the soil.

Figure 5 – Main Wreckage

The long line was separated in tension overload near the top of the line, a few feet from the cargo hook. Figure 3 shows the top portion of the long line still attached to the helicopter before the accident and figure 6 shows the postaccident condition of the long line. The cargo hook was found open at the accident site. The breakaway swivel, its shear pin, the two carabiners that hooked to either side of the swivel, and the upper portion of the long line were not found during the investigation. The aft end of the needle remained connected to the sock line via a non-breakaway swivel. The needle's fractured aft loop was found about 50 yards south of the accident site. Except for the fracture after loop, the rest of the needle remained intact with ground impact damage.

Figure 6 – Long line, Sheath, and Grappling Hook

A postaccident test confirmed mechanical and electrical continuity to the cargo hook. The mechanical switch on the cyclic was actuated, and the hook opened as expected. An electrical source was applied to the hook wiring, and the hook opened as expected.

The trim switch was fractured from the cyclic stick. The trim switch wires w...