Hughes 269A N90636 accident near Cleburne, Texas

Probable cause

The student pilot's failure to maintain tail rotor clearance from terrain while transitioning to a hover taxi and the instructor pilot's inadequate remedial action to prevent the impending tail rotor contact.

NTSB analysis

The student pilot was air taxiing the helicopter with an instructor pilot on board. When the student pilot slowed to a hover taxi, the helicopter began bucking violently fore and aft. The helicopter descended and came to rest on its side. A postaccident examination of the wreckage and accident site revealed ground scars consistent with main and tail rotor blade strikes, which were consistent with the aft left skid and tail rotor contacting the ground while the helicopter was moving aft. A helicopter is customarily pitched with its tail low when the pilot performs a quick stop from an air taxi. Tail rotor drive shaft deformation was consistent with the tail rotor blade contacting the ground while being driven. No preimpact anomalies were detected that would have precluded normal operation of the helicopter. The evidence indicates that the student pilot allowed the tail rotor and aft skid to contact the ground as the helicopter slowed during the transition to hover taxi. The instructor did not anticipate the situation or intervene in a timely manner, which resulted in an uncontrolled descent and rollover.

Text from the NTSB. Open the NTSB docket for CEN14LA222 for the full record.