Accident
On April 14, 2009, about 1935 Alaska daylight time, a Piper PA-14 airplane, registration N4246H, sustained substantial damage during takeoff from Merrill Field in Anchorage, Alaska. The airplane was being operated by the pilot as a personal local flight under visual flight rules (VFR) and Title 14, CFR Part 91. The solo private pilot was not injured. Visual meteorological conditions prevailed at the time, and no flight plan was filed.
Incident Details
According to the pilot, during the takeoff roll, as he applied power, the pilot's seat slid backward while the airplane accelerated. This movement prevented him from reaching the rudder pedals to maintain directional control. As a result, the airplane ground-looped to the left, and the right wing struck the ground, causing structural damage. The pilot reported that there were no known mechanical problems with the airplane before the accident.
Investigation
An FAA inspector examined the airplane after the accident. The front seats had been modified with adjustable seat tracks under an FAA field approval. The modification included a mechanical stop intended to prevent the seat from being pulled too far forward and to ensure proper latching. However, the inspector found that the stop, which should have been installed on the left seat track, was instead installed on the right track. Because of this misplacement, the pilot was able to pull the seat locking pin forward of the last locking hole. The locking pin then fell between two screw heads, and with the pilot's weight forward on the seat, it created a false sensation that the seat was locked in position. During acceleration, with the pilot's weight on the back of the seat, the pin jumped over the screw head, causing the seat to slide backward.