Robinson Helicopter R22 BETA N817AB accident near Waipahu, Hawaii

Probable cause

The certified flight instructor's delayed remedial action and inadequate supervision during a practice autorotation. Contributing to the accident was the student pilot's excessive application of the throttle.

NTSB analysis

The certified flight instructor (CFI) and a student pilot, who held a foreign-issued fixed-wing certificate, were on a local training flight to practice autorotations. The CFI demonstrated the first autorotation. Prior to letting the student take the controls, she reviewed the recovery procedure again. The CFI remained on the controls while the student made the control applications. One autorotation was performed successfully. The student entered his second autorotation, and, at 1,000 feet above ground level, the CFI requested that the student perform a recovery. Rather than cracking the throttle as demonstrated, the student rolled on the throttle, and the CFI felt a yaw to the right. The CFI took control of the helicopter and countered the yaw with left pedal. The CFI noted that the engine rpm and rotor rpm were excessively high, so she decreased the throttle to lower the engine rpm. She began to raise the collective to lower the rotor rpm, but neither of the rpm needles decreased. The helicopter was maintaining a level attitude, but it was descending. During the landing, the low rotor rpm horn sounded, the helicopter touched down hard, and the tail boom separated. The CFI reported no preimpact mechanical malfunctions or failures with the helicopter that would have precluded normal operation.

Text from the NTSB. Open the NTSB docket for WPR12CA056 for the full record.