The airline transport pilot had performed three touch-and-go maneuvers without braking at the airport in Kenosha, Wisconsin.
On the fourth and last planned landing roll about 30 mph, the Stearman PT17 experienced an excessive tailwheel shimmy. About 25 mph, the airplane nosed over and came to rest inverted.
Post-accident examination of the airplane revealed that the left main wheel/brake assembly was locked so the wheel/tire could not be rotated.
Partial disassembly of the wheel/brake assembly revealed a failed retaining bolt for the brake backing plate and a crack in the backing plate. The bolt likely broke off and became lodged in the assembly.
It is likely the failed retaining bolt and cracked backing plate resulted in a shift of the brake lining to contact the brake drum and led to a subsequent wheel lock when the brakes were applied.
Probable cause: The failed retaining bolt and cracked backing plate, which resulted in a shift of the brake lining to contact the brake drum and a subsequent wheel lock when the brakes were applied.
NTSB Identification: CEN18LA360
This August 2018 accident report is provided by the National Transportation Safety Board. Published as an educational tool, it is intended to help pilots learn from the misfortunes of others.
