CEN14LA222

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.

On April 25, 2014, about 1430 central daylight time, a Hughes 269A helicopter, N90636, impacted terrain following a descent from a hover taxi at the Cleburne Regional Airport (CPT), near Cleburne, Texas. The flight instructor and student pilot sustained minor injuries. The helicopter sustained substantial fuselage and main rotor damage. The helicopter was registered to and operated by a private individual under the provisions of 14 Code of Federal Regulations Part 91 as an instructional flight. Day visual flight rules conditions prevailed for the flight, which did not operate on a flight plan. The local flight originated from CPT about 1230. According to the student pilot's accident report, he was flying the helicopter in an "air taxi" and slowed to a "hovering taxi." The helicopter began bucking violently fore and aft. He indicated that the helicopter descended and came to rest on its side on the ground. A statement from the flight instructor, in part, said: I have read [the student pilot's] statement and agree with it. I have no recollection of the beginning but, I remember seeing and feeling being shaken and stirred, violently, then being helped out of the aircraft. At 1435, the recorded weather at CPT was: Wind 120 degrees at 11 knots; visibility 10 statute miles; sky condition clear; temperature 28 degrees C; dew point 6 degrees C; altimeter 30.00 inches of mercury. A Federal Aviation Administration inspector examined the wreckage and took pictures of the accident site. According to the orientation of ground scars, the direction the helicopter was heading was about 145 degrees. The ground scars were on a ramp where there were buildings to the east and southeast of the accident site. The observed ground scars were consistent with main rotor blade and tail rotor blade strikes. A safety investigator from the helicopter manufacturer examined the photographs. According to the manufacturer's investigator, the ground scars from the main rotor and tail rotor blades and the helicopter damage are consistent with the aft left skid contacting the ground while the aircraft was moving aft. A helicopter is customarily pitched tail low when a quick stop from an air taxi is performed. Main rotor blade ground scars were to the left and aft of the fuselage. A torsional deformation of the tail rotor drive shaft is visible at the forward end of the tail boom consistent with the tail rotor blade contact the ground while being driven. The on-scene examination and review of photographs did not reveal any pre-impact anomalies that would have precluded normal operation of the helicopter.