What happened
On January 25, 2020, an experimental, amateur-built Mustang II aircraft, registered UNREG, crashed near Big 'T' Airport (64GA) in Senoia, Georgia. The flight was being conducted under Part 91 regulations for personal use.
Witness video showed the aircraft performing two high-speed, low passes over the airport earlier that day. During the accident flight, the pilot performed six rolls and a barrel roll. Shortly after the barrel roll, the canopy and vertical stabilizer separated from the aircraft. As the plane descended in a nose-down attitude, the outboard section of the right horizontal stabilizer also detached. The aircraft impacted terrain in a wooded area approximately 0.5 miles south of the airport. The pilot and passenger sustained 2 fatal injuries.
The investigation
Investigators examined the wreckage and found the main components at the impact site, while the canopy and vertical stabilizer were located approximately 0.25 miles north of the main wreckage. The propeller had separated from the engine, with one blade showing tip curling and gouging, and the other showing s-bending near the tip.
An examination of the canopy frame revealed that the left aft corner junction and horizontal tube had failed due to overstress. Notably, the reinforcing gussets recommended by a 1984 kit manufacturer revision were not installed in the frame.
Metallurgical analysis of the vertical stabilizer identified fatigue cracking originating from the internal corner of the aft doubler rib. Ratchet marks consistent with stress and multiple fatigue crack initiations were observed along the internal edge of the aft doubler rib.