Bell Helicopter Textron Canada 429 N507TJ accident near Elba, New York

Probable cause

The pilots’ inappropriate flight control inputs while in vortex ring state, which resulted in main rotor blade contact with the tail boom and a subsequent in-flight breakup. Also causal was the flight instructor’s inadequate monitoring of the flight.

NTSB analysis

The flight instructor was providing recurrent training to the operator’s pilots. During the first training flight of the day, a pilot who received instruction from the flight instructor described that the instructor told him to perform a vortex ring state (VRS) recovery maneuver, which the pilot accomplished, but shortly afterwards, the instructor requested that the pilot perform the maneuver again. During the second entry into VRS, the helicopter developed a very high descent rate, and the pilot was surprised when the flight instructor pilot did not intervene as the helicopter got deeper into the state. The pilot, feeling uncomfortable at that point, exited the very high descent rate on his own rather than waiting for further guidance from the instructor. The remainder of the first flight was uneventful.

The second training flight of the day was the accident flight. A review of the recovered parametric data for this flight showed that the helicopter had been performing training maneuvers, and that shortly before the accident the helicopter was operating within the VRS envelope with a vertical descent rate between -800 to -1,300 feet per minute (fpm). This was consistent with the instructor directing the accident pilot to enter VRS for training purposes. Shortly thereafter, multiple abrupt control inputs were recorded, which including a forward cyclic input, followed by a nearly full-aft cyclic input within 1 second, as well as a concurrent full-down collective input with an increasing left pedal input. Based on contact signatures found on the helicopter’s main rotor blades and tailboom after the accident, it is likely that these abrupt control inputs resulted in the main rotor blades contacting the tail boom and the subsequent in-flight breakup of the helicopter. The parametric data and physical evidence observed during a postaccident examination of the wreckage revealed no evidence of any mechanical malfunctions or failures of the helicopter that would have precluded recovery from VRS. Based on this information, the reasons why the pilot(s) might have applied these abrupt control inputs could not be determined. Given the contextual commentary from the pilot of the previous training flight, it is likely the flight instructor did not provide adequate information to the accident pilot on how he would receive training for VRS, to include how they would identify, enter, and exit VRS.

Text from the NTSB. Open the NTSB docket for ERA22FA207 for the full record.