Piper PA-14 N4246H accident near Anchorage, Alaska

Probable cause

The pilot's inability to maintain directional control due to the pilot's seat sliding back during takeoff as a result of maintenance personnel's incorrect installation of the seat's forward track stop.

NTSB analysis

The private pilot said that his seat slid back when he applied power for takeoff and that he was unable to reach the rudder pedals to maintain directional control, causing the airplane to ground-loop to the left and the right wing to strike the ground. The airplane sustained structural damage to the right wing during the accident. The pilot said that there were no known mechanical problems with the airplane prior to the accident. A Federal Aviation Administration inspector who examined the airplane said that the front seats of the accident airplane had been modified with adjustable seat tracks with FAA field approval. He said that the mechanical seat stop, which was supposed to be installed on the left track, had been installed on the right track. The stop was needed to keep the seat from being pulled too far forward. Because the stop was installed on the wrong track, he said the pilot was able to pull the seat locking pin forward of the last locking hole. The locking pin fell between two screw heads, giving it the feeling of being secured. He said that during acceleration the locking pin jumped over the screw head, and the seat slid back.

Text from the NTSB. Open the NTSB docket for ANC09LA032 for the full record.