What caused the right main landing wheel to lock up forcing a single-engine light airplane to flip over at Dillingham Field on Oahu remains undetermined, according to federal investigators.

But it is possible the locked brake and wheel might have been jammed by a rock or other foreign object, according to findings released Thursday by the National Transportation Safety Board.

The pilot of a Cessna 305, being operated by the Honolulu Soaring Club, received minor injuries in the accident on Nov. 7, 2013, but the airplane sustained substantial damage, investigators said.

Investigators confirmed the right brake was locked and the tire would not rotate normally when examined at the accident site.

After the airplane was recovered and taken to a hangar, the right brake was disassembled and no irregularities were found, the investigation found. After the re-assembly, the brake operated normally.