Amateur-built ACRODUSTER II SA750 N363J accident near Panama City, Florida

Probable cause

The pilot's inability to recover from an intentional aerobatic maneuver due to loss of aileron control. Contributing to the accident was the installation of an inadequate aileron secondary stop block against the main spar of both lower wings.

NTSB analysis

The passenger reported that the pilot had performed a thorough preflight inspection of the airplane and that after takeoff he performed aerobatic maneuvers over a practice area. Before the last maneuver the pilot asked the passenger if he wanted to perform what he thought was a tail slide. The flight climbed to 3,500 feet and the pilot initiated the maneuver and, after falling for a few seconds, attempted to recover. The pilot appeared to bring the nose level briefly with full power, but the airplane then started rolling to the left and right, as well as up and down, and the pilot announced that there was a malfunction. The pilot informed him to bail out of the airplane, which he did. The airplane crashed inverted in a heavily wooded area, and the passenger was unharmed. Following recovery of the airplane, inspection of the elevator and rudder flight controls by a Federal Aviation Administration inspector revealed no evidence of preimpact failure or malfunction. Inspection of the aileron flight control system revealed that wooden aileron secondary stop blocks were attached to the main spars; however, the shape was different than the stop block depicted in the builder's guide. Additionally, scrape marks associated with each aileron outer bellcrank were noted on structural support tubes inside both lower wings.

Text from the NTSB. Open the NTSB docket for MIA08LA121 for the full record.