Thorp T-18, N25VP: Accident occurred December 20, 2014 at San Rafael Airport (CA35), Marin County, California

Aviation Accident Final Report - National Transportation Safety Board: https://app.ntsb.gov/pdf

Investigation Docket - National Transportation Safety Board: https://dms.ntsb.gov/pubdms

Aviation Accident Data Summary - National Transportation Safety Board: https://app.ntsb.gov/pdf

http://registry.faa.gov/N25VP




NTSB Identification: WPR15CA066
14 CFR Part 91: General Aviation
Accident occurred Saturday, December 20, 2014 in San Rafael, CA
Probable Cause Approval Date: 02/11/2015
Aircraft: FERDON THORP T 18, registration: N25VP
Injuries: 1 Uninjured.

NTSB investigators used data provided by various entities, including, but not limited to, the Federal Aviation Administration and/or the operator and did not travel in support of this investigation to prepare this aircraft accident report.

The pilot reported that prior to the flight in the experimental airplane, he unbolted and rebolted the pilot's seat from its middle position to the forward position. He did not check to see if the flight control stick movement would be restricted in this new configuration. 

During the takeoff roll, the airplane would not rotate when he moved the flight control stick aft. Not realizing the seat prevented the flight control stick movement to the full aft position, the pilot adjusted the elevator trim and the airplane subsequently lifted off, however, it would not climb. The pilot then aborted the takeoff; however, the airplane did not have sufficient distance to stop. It departed the runway surface and traversed through a field, impacted trees, and came to rest inverted. The airplane sustained substantial damage to the wings, rudder, and vertical stabilator. The pilot reported no preimpact mechanical malfunctions or failures with the airframe or engine that would have precluded normal operation.

The National Transportation Safety Board determines the probable cause(s) of this accident as follows:
The pilot's delayed decision to abort the takeoff. Contributing to the accident are an inadequate modification to the seat position, and the pilot's failure to check flight controls for freedom and correct movement.