Primary finding
Probable cause
The pilot's inadequate preflight inspection of the airplane.
Investigator assessment
Analysis narrative
The pilot stated that he performed a preflight inspection of the airplane but did not use a checklist. He performed "preflight checks", an "engine run-up" and checked the flight controls before takeoff. During the takeoff run while flying on the step before lifting off, "something let go and all of a sudden the aircraft was upside down." He further stated, "He did a poor job inspecting this aircraft" and he "...overlooked" the missing nut from the right horizontal stabilizer. Postaccident inspection of the airplane by an FAA inspector revealed the forward attach point of the right horizontal stabilizer was not secured. The attach nylon lock nut was missing and the bolt which secures the right horizontal stabilizer was backed out of the forward attach point .
Source record
Factual narrative
The pilot stated that he performed a preflight inspection of the airplane but did not use a checklist. He performed "preflight checks", an "engine run-up" and checked the flight controls before takeoff. During the takeoff run while flying on the step before lifting off, "something let go and all of a sudden the aircraft was upside down." He further stated, "He did a poor job inspecting this aircraft" and he "...overlooked" the missing nut from the right horizontal stabilizer. Postaccident inspection of the airplane by an FAA inspector revealed the forward attach point of the right horizontal stabilizer was not secured. The attach nylon lock nut was missing and the bolt which secures the right horizontal stabilizer was backed out of the forward attach point .