Accident Summary
On September 22, 2018, about 1515 eastern daylight time, a Beech V35 airplane, registration N435RB, was substantially damaged in an accident near Georgetown, South Carolina. The flight instructor and the private pilot sustained minor injuries. The airplane was being operated as a Title 14 Code of Federal Regulations Part 91 instructional flight.
Flight Details
The flight instructor reported that he was providing instruction for a complex/high performance endorsement. After about 30 minutes of flight, while returning to the airport, the instructor took control to allow the pilot to get a drink of water. During that time, the airplane entered an uncommanded yaw and roll to the right and began to pitch up. The instructor confirmed the pilot was not touching the controls. By applying left rudder, left aileron, and forward elevator pressure, and trimming the elevator nose down, the instructor maintained some control. As he prepared to land on runway 11, the right yaw increased with decreasing speed. At 80 mph, it became impossible to maintain alignment with the runway centerline, and the airplane drifted right. After touchdown, it immediately veered right about 90 degrees and collided with trees, causing substantial damage to the firewall, fuselage, and both wings.
Postaccident Examination
Examination of the flight control system revealed that the left seat’s left rudder pedal arm clevis was fractured in multiple locations. Metallurgical analysis identified cracks and voids that originated during the casting (manufacturing) process. These voids, cracks, and oxide layers reduced the cross-sectional area capable of withstanding applied loads. When sufficient force was applied, the remaining material fractured in overstress. The separation of the pedal arm from the pushrod resulted in a failure of the rudder control system.
Logbook Review
Review of the airframe logbooks indicated that the rudder pedal arm was original to the airplane, installed at the time of manufacture in 1966. At the time of the accident, the airplane had accumulated a total of 6,203.62 flight hours.