Grumman American Avn. Corp. AA-5B N23JK accident near Camdenton, Missouri

Probable cause

The inadequate maintenance of the seat locking mechanism, which resulted in the pilot’s seat sliding back during takeoff and a subsequent loss of control.

NTSB analysis

During the takeoff roll the pilot’s seat suddenly slid backward, and she was unable to reach the pedals, which resulted in a loss of control and runway excursion. Examination of the airplane revealed substantial damage to the engine mount, fuselage, and horizontal stabilizer. The pilot’s seat tracks were a newer heat-treated version. There were wear marks on the seat lock pin tip indicative of previous alignment issues. The spring that held the lock pins in place was installed incorrectly and the corresponding push-pull rod was bent. This incorrect spring placement shortened the travel of the spring and reduced the tension on the lock pins. The seat brackets that attach to the spar exhibited worn and elongated bolt holes, which created a misalignment of the seat support. It’s likely that the condition of the seat locking mechanism prevented the seat from locking correctly, which resulted in the seat sliding back during takeoff.

A review of the available airframe maintenance records did not reveal any entries regarding inspections or work performed on the seats or the seat tracks. The investigation was unable to determine when the pilot’s seat was last inspected, when the lock pin spring was incorrectly installed, and by whom.

Text from the NTSB. Open the NTSB docket for CEN24LA315 for the full record.