Accident Sequence
The aircraft was performing aerobatics when it entered a dive, gained speed, leveled off, and then pulled up abruptly. During the pull-up, the right wing failed upward and separated from the aircraft. The aircraft subsequently went out of control and crashed.
Pilot and Seat Condition
The pilot was wearing a parachute but did not bail out. He was found strapped into his seat, and the door release pin was still in place. Examination of the pilot's seat revealed that the tubular ends of the seat-back frame had failed at the pivot points. These pivot points are designed to allow the seat-back to pivot forward over the seat pan, enabling entry to the aft seat. The attaching bolts at the pivot points had pulled through the ends of the frame. Evidence of overstress shear was found at the right pivot point, indicating the seat-back had failed in the aft direction. At the left pivot point, evidence of overstress shear and twisting deformation was found.
Aircraft Damage
Post-crash examination showed evidence of upward bending of the left wing. Both horizontal stabilizers exhibited evidence of being compromised in a downward direction.
Historical Context
Bellanca 7 and 8 series aircraft have experienced several seat-back failures at the hinge point or at the welded junction of the seat's lower side tube and seat-back side brace.