What happened
On April 26, 2022, a Bell 429 helicopter, registration N507TJ, was involved in a fatal accident near Elba, New York, during a scheduled instructional flight. The flight was part of a recurrent training program operated by MERCY FLIGHT INC. The crew, consisting of a flight instructor and a pilot receiving instruction, sustained 2 fatal injuries.
Prior to the accident, the aircraft had performed several training maneuvers, including single-engine and dual-engine failure training with autorotations. Data from the aircraft's flight recorders and ADS-B indicated that the helicopter was operating in an envelope conducive to vortex ring state (VRS) for approximately 18 seconds. During this period, the aircraft's vertical descent rate increased from -800 to -1,300 feet per minute.
Immediately following this period, the aircraft experienced multiple abrupt control inputs. The cyclic was moved nearly full forward and to the left, followed rapidly by a nearly full-aft input within one second. Simultaneously, the collective was moved to a full-down position. These inputs led to the main rotor blades contacting the tail boom, causing the aircraft to break up in flight before impacting the terrain.
The investigation
Investigators analyzed data from the aircraft's Electronic Data Recorder (EDR), the SKYTRAC transceiver, and ADS-B. The recovered engine data from the No. 2 engine showed no mechanical faults or exceedances.
Physical examination of the wreckage revealed that the fuselage struck electrical distribution wires upon impact. The tail boom had fractured and separated into two sections, with fracture lines consistent with main rotor blade contact. The four main rotor blades were recovered from the debris field; examination showed that the blades had struck the tail boom, an antenna, and the tail rotor drive shaft.
Analysis of the flight control and hydraulic systems showed no evidence of pre-impact mechanical irregularities or failures. The investigation also included a vehicle performance study, which confirmed the helicopter had penetrated the VRS envelope. A blade arc study performed by the manufacturer confirmed that the recorded control inputs could cause the rotor blades to strike the tail boom and other components.