Hughes 269C N1088Y accident near Ramona, California

Probable cause

The flight instructor’s failure to follow the proper procedure while demonstrating a practice autorotation, which resulted in a total loss of engine power and subsequent hard landing.

NTSB analysis

The flight instructor stated that he initiated the autorotation demonstration maneuver between 600 to 700 feet above ground level (agl) by rolling off the throttle and splitting the needles. About 300 feet agl, he initiated the recovery; however, he then noticed that the engine rpm was near zero and that the engine would not respond to throttle input. About 100 feet agl, the airspeed was about 40 knots, and the rotor rpm was on the low side of the green arc. The helicopter subsequently landed hard, slid forward, rolled over, and came to rest on its right side. A postaccident examination revealed no anomalies with the engine that would have precluded normal operation. The company chief pilot stated that, shortly after the instructor was hired, he showed the instructor the proper technique for teaching autorotations, which did not include rolling the throttle off in flight, a procedure that could result in engine stoppage. About 4 months after the accident, the Federal Aviation Administration issued Special Airworthiness Bulletin SW-12-12, “Conducting Engine-Failure Simulation in Helicopters with Reciprocating Engines.” The bulletin cautions owners and operators of Schweizer 269C and 269C-1 helicopters to avoid throttle chops to full idle in order to minimize the possibility of engine stoppage.

Text from the NTSB. Open the NTSB docket for WPR11LA462 for the full record.