Schweizer 269C N17YS accident near Las Vegas, Nevada

Probable cause

A total loss of engine power during a practice autorotation for reasons that could not be determined.

NTSB analysis

The flight instructor reported that, during the instructional flight in the helicopter, he was demonstrating entry procedures for an autorotation with the student pilot following along on the flight controls. The instructor smoothly lowered the collective, applied right pedal, and pulled aft on the cyclic to enter the autorotation. Immediately after entering the maneuver, he heard a change in engine noise and saw that the engine rpm gauge indicated zero. The instructor attempted to restart the engine by pressing the start button several times; however, the starter did not engage. The instructor continued the autorotative descent to the ground and landed hard.

A postaccident engine examination revealed that the battery's positive lead was separated from the battery terminal, and the lead exhibited corrosion. When the positive lead was reattached to the battery, and the engine started and operated normally. The reason for the loss of engine power during the autorotation could not be determined.

Text from the NTSB. Open the NTSB docket for WPR15LA245 for the full record.