Incident Description
During the landing roll, a World War II era tailwheel-equipped airplane experienced an uncontrollable swerve as the right main landing gear began to collapse. The aircraft veered, and the right main gear exited the edge of the runway. Subsequently, the airplane rocked forward onto its nose, causing the propeller and left wing tip to impact the ground. The aircraft then rocked back and came to rest partially off the runway in an upright position with a right wing low attitude.
Investigation Findings
An examination of the landing gear retraction system revealed that the landing gear handle detent was contaminated with paint. This contamination prevented the landing gear handle from remaining securely in the detent position. Consequently, the right landing gear downlock pin partially retracted, which led to the partial retraction of the right main landing gear.
Conclusion
The investigation determined that the landing gear handle detent contamination resulted in the partial retraction of the right main landing gear, causing the collapse and subsequent loss of directional control during the landing roll.