NTSB Identification: DFW07CA096.
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Accident occurred Wednesday, April 25, 2007 in Spring, TX
Probable Cause Approval Date: 03/31/2008
Aircraft: Robinson R-22 Beta, registration: N7534S
Injuries: 2 Uninjured.
NTSB investigators used data provided by various entities, including, but not limited to, the Federal Aviation Administration and/or the operator and did not travel in support of this investigation to prepare this aircraft accident report.
The helicopter experienced dynamic rollover and came to rest on its left side while attempting to take off. The flight instructor reported in the NTSB Form 6120.1 (Pilot/Operator Aircraft Accident/Incident Report) that the instructional flight comprised of practice autorotations and rapid decelerations or quick-stops. The practice area where these maneuvers were performed was reported by the flight instructor as "a grassy, dirt area with occasional dirt mounds raising approximately 1 and 1/2 feet above the ground". The ground was also wet and muddy due to thunderstorms having passed through the area prior to the flight. While executing the third quick-stop maneuver, the student pilot receiving instruction performed a normal takeoff from a 3-foot hover. The helicopter assumed a pronounced nose low attitude while accelerating during takeoff and the toe of the right landing gear skid simultaneously contacted a dirt mound. The student attempted to correct the right yawing condition by over-controlling to the left, while the flight instructor compensated by raising the collective and applying right cyclic. The flight instructor concluded that "by the time the inputs were felt the helicopter had reached its critical angle and rolled [to the] left side." The helicopter sustained structural damage to the main rotor, fuselage, tail boom, and tail rotor. The flight instructor and student pilot were able to exit the helicopter unassisted and neither was injured. At the time of the accident the flight instructor reported having accumulated 116 hours as a flight instructor and the student had accumulated a total of 24 hours in helicopters. The weather at the accident site was reported as calm winds, 10 miles visibility, a broken ceiling at 2,100 feet, and a temperature of 26 degrees Celsius.
The National Transportation Safety Board determines the probable cause(s) of this accident to be: The student pilot's improper use of the flight controls resulting in dynamic rollover. Contributing factors were the delayed remedial action by the flight instructor and the uneven, muddy terrain conditions. Full narrative available
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