Amateur-built EXEC N314AC accident near Plymouth, Indiana

Probable cause

A loss of control due to the failed forward tail rotor belt as a result of the owner’s failure to follow the helicopter manufacturer’s tail rotor belt replacement recommendations.

NTSB analysis

The helicopter owner/pilot reported that while he and his flight instructor were practicing an autorotation, the flight instructor heard a noise. Shortly thereafter, the helicopter started to yaw to the left and the airspeed decreased. The flight instructor took over control of the helicopter and initiated an autorotation to a corn field. The right skid caught the ground, and the helicopter rolled onto its right side. The main rotor and fuselage sustained substantial damage.

A postaccident examination revealed that the forward tail rotor belt broke. The belt was found frayed at the separation point. A review of the tail rotor maintenance records revealed that the tail rotor belts had not been replaced since 2006. The manufacturer recommends tail rotor belt replacement at 250 hours, 2 years, or as needed upon conditional inspections, whichever comes first. The operator reported that before the accident the belts appeared to be in satisfactory condition but acknowledged they were beyond the 2-year service life and should have been replaced.

Text from the NTSB. Open the NTSB docket for CEN25LA013 for the full record.