Accident Details
On April 4, 2024, at 1445 Pacific daylight time, a Cessna 180A (N5281D) was substantially damaged during an instructional flight at Priest Lake United States Forest Service Airport (67S) near Nordman, Idaho. The pilot and flight instructor onboard were not injured. The airplane was being operated under Title 14 Code of Federal Regulations Part 91 for tailwheel training, which was required by insurance. The pilot had purchased the tailwheel-equipped airplane one month prior.
Sequence of Events
Earlier in the day, the pilot and instructor had conducted about a dozen landings at various local airports. During a power-off approach, the airplane developed a higher-than-normal sink rate. The instructor called for additional power, but the engine briefly hesitated when power was applied. The instructor then managed the power and applied aft yoke to flare, resulting in a firm touchdown with a minimal bounce. During the bounce, the left main wheel axle assembly separated from the landing gear leg. The exposed landing gear leg then contacted the grass surface and separated from the airframe. The fuselage and left wing contacted the ground, sliding on the left wing and the right main landing gear wheel, causing substantial damage to the left wing. The airplane came to rest upright, with its nose oriented 180° to the landing direction. The associated nuts were not recovered from the accident site.
Metallurgical Examination
Examination of the left main landing gear axle assembly revealed that all four bolts remained installed through the flange mated with the leg. The bolts exhibited bending and tensile loading near the fracture, with some threads completely sheared off, consistent with shearing of nuts from the attachment bolts due to landing forces. The axle surfaces showed fretting wear indicative of repeated oscillatory loads between loose joints. The thread damage suggested the nuts may have been engaged only at the bolt ends. Additionally, fatigue cracking was found on the landing gear leg surface, originating from a corrosion pit that had propagated upward through the leg.
Maintenance History
According to maintenance records, an annual inspection including brake and wheel work had been completed on March 20, 2024. Additionally, on June 1, 2023, the main landing gear had been removed for installation of floats.