SEA02LA039 · Bitton/Sport Flight Aviation Talon

A witness reported seeing the accident aircraft in level flight traveling westbound at an estimated altitude of 800 feet above ground (AGL). The witness stated that about five minutes later he observed the accident aircraft in a "vertical dive" from an estimated altitude of 350 AGL. He stated that the vertical dive continued until approximately 150 feet AGL where he observed the pitch attitude change to a nose high attitude. Shortly thereafter the witness lost sight of the aircraft when it descended behind a building. An inspector from the Federal Aviation Administration (FAA), Flight Standards District Office (FSDO) conducted the onsite examination and reported that the aircraft impacted terrain in a nearly vertical attitude and extensive impact damage was noted to the airframe, flight controls and cockpit area. Subsequent to the accident, family members of the pilot notified the NTSB Investigator-in-Charge (IIC) that during the wreckage recovery it was noted that a flight control linkage bolt and retaining nut (used to secure the control linkage to the elevator bell crank) was missing from its installed position. According to family members of the pilot, a bolt matching the description and dimensions of linkage bolt was found in the area of the wreckage, however, it was not determined whether or not it was the bolt in question, or if it had separated from its installed position before or after impact.

Verbatim NTSB analysis and probable cause from the NTSB dataset