Champion 7GCBA N9512S accident near Athol, Idaho

Probable cause

The failure of the right brake due to a disconnected master cylinder piston rod, which led to the departure of the airplane from the runway surface. Contributing to the accident was the mechanic’s failure to adequately inspect the connection between the piston rod and rudder pedal.

NTSB analysis

The pilot of the tailwheel-equipped airplane reported that the accident flight was uneventful from takeoff to touchdown. However, during the landing roll, the right brake was inoperative, causing the airplane to veer to the left and off the runway surface into a ditch, which resulted in the right main landing gear collapsing and the right wing impacting terrain.

A postaccident examination of the airplane revealed that the right brake master cylinder piston rod had disconnected from the right rudder pedal attach point, and that the cotter pin was missing from the clevis pin. The airplane had undergone a conversion to a hydraulic toe brake rudder assembly about 3 years before the accident. However, the investigation was unable to determine, from the available evidence for this accident investigation, if the cotter pin was not installed, improperly installed, or subsequently damaged.

The airplane’s an annual inspection was accomplished 12 days and about 1.3 flight hours before the accident. The mechanic who performed the inspection stated that he inspected the right brake system but did not recall or notice if the cotter pin was installed in the clevis pin. Given the short interval between the inspection and the accident, it is likely that the mechanic failed to adequately inspect the connection of the right rudder pedal to its brake system.

Text from the NTSB. Open the NTSB docket for WPR22LA324 for the full record.