American Champion Aircraft 7AC N85510 accident near Keene, New Hampshire

Probable cause

The disengagement of the tailwheel locking mechanism during the landing roll due to wear, and a subsequent loss of directional control. Contributing was the pilot's inadequate remedial action, which resulted in a runway excursion.

NTSB analysis

The sport pilot of the tailwheel-equipped airplane had completed one touch-and-go landing uneventfully on a 6,201-ft-long, 100-ft-wide asphalt runway. During the second landing, the tailwheel began to "shimmy." Rather than apply forward control stick pressure to reduce weight on the tailwheel and alleviate the shimmy, the pilot held the control stick fully aft as the airplane departed the left side of the runway and impacted an approach path indicator light. Examination of the tailwheel locking mechanism revealed that it was worn and had unlocked during touchdown. The pilot should have been able to compensate for a tailwheel shimmy at touchdown by reducing the weight on the tailwheel. The condition of the tailwheel locking mechanism should have been checked during the last annual inspection; however, it is possible that the locking mechanism could have worn further during the 7 months between the most recent inspection and the accident flight.

Text from the NTSB. Open the NTSB docket for ERA16LA174 for the full record.