History of Flight
On September 12, 2018, about 1245 mountain daylight time, a RotorWay Exec 90 experimental amateur-built helicopter, N166LC, was substantially damaged when it collided with a hangar at Billings Logan International Airport (BIL), Billings, Montana. The nonrated rotorcraft-helicopter pilot was fatally injured. The helicopter was operated as a Title 14 Code of Federal Regulations Part 91 personal flight.
An acquaintance who occupied the adjacent hangar reported that the pilot had purchased the helicopter about 3 years before the accident. The acquaintance stated that the pilot frequently hover-taxied the helicopter on airport property for testing but had not really flown it. On the morning of the accident, the pilot hover-taxied around the airport area, landed in front of his hangar, shut down the engine, and exited. The two spoke for about 15 minutes, during which the pilot said the helicopter was flying well with no issues. The pilot then reboarded, started the engine, and hover-taxied west parallel to the hangar row. He made a 90° left turn to the south and a 180° turn to the north, then hover-taxied north along the west end of the hangar row. The acquaintance did not witness the impact but heard the helicopter strike a hangar.
Personnel Information
A check of Federal Aviation Administration (FAA) records revealed that the pilot did not possess a rotorcraft-helicopter pilot certificate. No records of the pilot's flight time in rotorcraft-helicopter were recovered.
Aircraft Information
The accident helicopter was constructed with an aluminum tail and a full fiberglass cockpit enclosure. The engine had a centrifugal compressor and a radial inflow turbine. The most recent FAA certificate of registration was issued on June 28, 2015. A special airworthiness certificate was issued on December 8, 2015, authorizing operation as an amateur-built experimental category helicopter.
The pilot purchased the helicopter in September 2015. A build ledger found in the pilot's hangar indicated that the anti-torque pedals had been fabricated in December 1996.
Wreckage and Impact Information
The helicopter's main rotor blades struck the top of a 25-ft-tall hangar, and the fuselage impacted the hangar's forward door section. The helicopter came to rest partially inside the hangar, facing upward at an angle of about 30° on a magnetic heading of about 280°. There was fuel present but no postcrash fire. The cabin/cockpit top and sides were destroyed by impact forces. All flight-necessary components were accounted for, and flight control continuity was confirmed.
Both main rotor blades remained attached to their hubs. One blade showed severe bending and deformation. The tail rotor and gearbox assembly were intact and undamaged. The transmission remained in place and was not compromised. The engine was intact with no evidence of a catastrophic preaccident event; examination found no significant mechanical anomalies except for some damage to stationary power turbine vanes.
The cyclic, collective, and most anti-torque pedals were undamaged. However, the left anti-torque pedal for the right-seat position was found separated at the weld point of the vertical and horizontal tubes. Examination by the NTSB Materials Laboratory revealed that the fracture was consistent with a fillet joint exhibiting lack of complete fusion. The two anti-torque tube assemblies were inconsistent in measurements and materials. The fractured assembly's holes showed elongation and material loss consistent with wear. No other mechanical anomalies that would preclude normal operation were found.
Medical and Pathological Information
The Montana State Department of Justice performed an autopsy, which determined the cause of death as multiple blunt force injuries. Toxicological testing detected naproxen, rosuvastatin, doxylamine, and metoprolol. No carbon monoxide or ethanol were detected.