Amateur-built 162 N162RF accident near Passaic, Missouri

Probable cause

The electrical short in the main rotor rpm indicating unit which provided an inaccurate indication to the student pilot and resulted in substantial damage during the precautionary autorotation.

NTSB analysis

The student pilot reported that, about 10 minutes into the flight, he observed the main rotor rpm indicating unit drop to zero. The student confirmed that the engine rpm indications were "still normal" and then decided to execute an autorotation to an open field and lowered the collective. He stated that the helicopter was in a "steady glide" when he realized that it might impact a fence at his intended landing area in the field. The student applied aft cyclic to avoid the fence, which changed the helicopter’s glidepath; he then flared the helicopter and applied collective for the landing. During the landing, the right skid’s rear portion impacted terrain. The helicopter bounced, the student lost helicopter control, and the helicopter came to rest on its right side resulting in substantial damage.

Postaccident examination of the helicopter revealed an electrical short had occurred in the main rotor rpm indicating unit. Given the student reported that the engine rpm indications were “still normal," it is likely the helicopter was still functioning normally despite the loss of cockpit main rotor rpm indications.

Text from the NTSB. Open the NTSB docket for CEN19LA016 for the full record.