What happened
Shortly after takeoff, the surviving passenger noticed the aircraft began losing altitude. She heard the pilot comment about a clicking noise in the left wing, a sound she also perceived and described as metal clicking together. Ground witnesses observed a change in engine sound. While several reported an interruption of engine power, others, including the surviving passenger, did not report a total power loss. Subsequently, the aircraft crashed approximately 600 yards south-southeast from the approach end of runway 29. During impact, the left wing and nose were extensively damaged. After impact, the aircraft traveled only about 37 feet before coming to rest.
The investigation
An examination revealed that the number four exhaust pipe failed next to the welded flange that attached the pipe to the exhaust port. The fractures were discolored by exhaust gases and peened by repeated contact with the mating surfaces, making evaluation difficult. Much of the fracture was 90 degrees to the pipe surface, which is typical of fatigue. The flange had been previously repaired by putting a sleeve of material around the pipe and welding it to the flange. Some areas of the repair weld did not adhere to the sleeve or flange.
Findings
The failure was caused by fatigue of the exhaust pipe due to an incomplete repair weld on the flange.