Accident Details
On July 5, 2020, about 1124 Pacific daylight time, a Boeing B75, registration N61445, was substantially damaged in an accident near Chino, California. The pilot and passenger were not injured. The airplane was operated as a Title 14 Code of Federal Regulations part 91 personal flight.
Pilot Report
The pilot reported that during the landing roll on runway 26R, the left wing dipped, and he applied right aileron to counteract. The airplane began to turn to the right. Despite applying full left rudder, left brake, and a brief application of power, the pilot was unable to correct the movement. The lower left wing struck the ground, and the airplane veered sharply to the right, exiting the runway. Subsequently, the left main landing gear collapsed, and the airplane came to rest upright.
Postaccident Examination
Postaccident examination revealed that the fuselage was substantially damaged. The left rudder/tailwheel cable idler arm was found fractured. The idler arm was sent to the National Transportation Safety Board Materials Laboratory for further examination.
Fracture Analysis
Examination of the two pieces of the fractured left rudder/tailwheel cable idler arm showed that the fracture progressed through the central pivot portion of the arm. The surface features, surface roughness, and presence of parting lines were consistent with sand-casting fabrication of the arm. The fracture surfaces were relatively flat, and the peripheral edges did not exhibit deformation associated with in-plane contraction, consistent with fracture through a material of relatively low fracture toughness. Along the exterior of the T portion, minor in-plane plastic deformation was observed. Based on fractographic features, the fracture initiated at the ligament and progressed through the section due to a monotonic bending load.