YUKON, OK, USA
N684F
MCDONNELL DOUGLAS 369E
THE MANUFACTURER'S TRAINING PILOT WAS CONDUCTING UNAPPROVED 'ZERO AIRSPEED' AUTOROTATION TRAINING IN CONJUNCTION WITH ANNUAL PROFICIENCY TRAINING FOR THE POLICE AVIATION SUPPORT UNIT. HE WAS NOT A CERTIFIED FLIGHT INSTRUCTOR. AFTER HE DEMONSTRATED THE MANEUVER, THE POLICE PILOT ATTEMPTED IT. THE HELICOPTER CONTACTED THE GROUND WITH LOW MAIN ROTOR RPM AND NOT IN A LEVEL ATTITUDE. THE MAIN ROTOR BLADES SEVERED THE TAIL OF THE HELICOPTER. THE POLICE PILOT STATED THAT THIS AND OTHER EMERGENCY PROCEDURE MANEUVERS WERE NOT COVERED IN THE BRIEFING CONDUCTED BEFORE THE FLIGHT.
THE DUAL STUDENT'S FAILURE TO MAINTAIN ADEQUATE MAIN ROTOR RPM AND FAILURE TO LEVEL THE HELICOPTER AT TOUCHDOWN. FACTORS WERE THE MANUFACTURER'S TRAINING PILOT'S INADEQUATE SUPERVISION AND THE DUAL STUDENT PERFORMING THE MANEUVER.
Source: NTSB Aviation Accident Database
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