Amateur-built Buzzard N84BS accident near Lincoln, California

Probable cause

A loss of control due to the mechanical disconnection of an aileron pushrod from its bellcrank as a result of the mechanic's failure to properly secure the pushrod attach hardware. Also causal was the pilot's inadequate preflight inspection.

NTSB analysis

The single-seat aircraft was registered with the Federal Aviation Administration (FAA) as an experimental, amateur-built aircraft. A week before the accident, the aircraft was assembled by a certificated aircraft mechanic. The pilot reported that he had previously flown the aircraft one time, for about 30 minutes. During the accident flight's takeoff roll, the pilot noticed that the aircraft did not "feel right," but he opted to continue. About 250 feet above the ground the outboard right wing "started to flutter in a violent way" and in response the pilot reduced engine power and aircraft speed. He then "lost all control." The aircraft impacted the ground in a field and seriously injured the pilot. About an hour after the accident skydivers noticed the wreckage and summoned emergency services to rescue the pilot. Examination of the wreckage by an FAA inspector revealed that the bolt that was supposed to attach an aileron pushrod to the outboard aileron bellcrank was lying loose in the bottom of the wing bay; neither the nut nor the cotter pin was recovered. Examination of the opposite aileron bellcrank revealed that the corresponding bolt and nut were not secured by a cotter pin, despite provisions for one. The mechanic who assembled the aircraft stated that he did not install cotter pins in either of the two noted bolts. The pilot stated that he did not inspect the aircraft after assembly or before the flight.

Text from the NTSB. Open the NTSB docket for WPR10CA398 for the full record.