WPR23LA102

The pilot receiving instruction and flight instructor reported that, during the landing roll, while slowing the airplane in preparation to exit the runway, the airplane abruptly turned to the right. Despite the application of left rudder and left brake, the airplane continued to the right and ground looped. The pilot taxied the airplane back to his hangar and noticed that the rudder inputs needed were not typical. Upon examination at his hangar, he discovered substantial damage to the left wing, left horizontal stabilizer and elevator. He also noted that the right main landing gear leg was misaligned, and the right main landing gearbox assembly was fractured. Postaccident examination of the right main landing gearbox revealed evidence of fatigue cracking within the hollow slot of the assembly and subsequent overstress fractures outside of the fatigue zone.

On January 31, 2023, about 1145 Pacific standard time, a Cessna 175, N9235B, sustained substantial damage when it was involved in an accident near Hayden, Idaho. The pilot and flight instructor were not injured. The airplane was operated as a Title 14 Code of Federal Regulations Part 91 instructional flight. The pilot receiving instruction reported that, during the landing roll, he slowed the tailwheel-equipped airplane to exit the runway at taxiway B. Without warning, the airplane began an abrupt right turn. The pilot applied full left rudder and left brake; however, the airplane continued the right turn and ground looped. He did not see damage to the airplane and decided to taxi clear of the runway and back to his hangar. The flight instructor reported that, “...it seemed to take a significantly greater application to get the airplane moving, and the pilot seemed to have to use left rudder to taxi the airplane straight.” The pilot receiving instruction reported that, “...the controls were not behaving true.” After exiting the airplane, they discovered substantial damage to the left wing, left horizontal stabilizer, and left side of the elevator. The right main landing gear leg was misaligned, and the gearbox assembly was fractured. The right main landing gearbox assembly was removed and retained for further examination. Maintenance records showed that the most recent annual inspection was completed on 12/22/22. They also showed that the right main landing gear outboard saddle (part number 175-8) was repaired in September of 2019 and again in May of 2020. Postaccident examination and fracture analysis of the right main landing gearbox assembly was conducted by the National Transportation Safety Board Materials Laboratory. The examination revealed evidence of fatigue cracks within the hollow slot of the gearbox assembly. Outside the zone of the fatigue cracking, the fracture surfaces exhibited coarse features, typical of overstress.