This August 2007 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.
Aircraft: Piper Twin Comanche.
Location: Lawrence, Kan.
Aircraft damage: Substantial.
What reportedly happened: The pilot made five touch-and-go landings at an airport before flying home. When he lowered the landing gear in preparation for landing, he noticed in the engine nacelle mirror that the landing gear was only one-third extended. He departed the airport area to troubleshoot the problem.
He noticed that the main landing gear circuit breaker had tripped. After several attempts to extend the landing gear manually, it extended about two-thirds of the way. The pilot kept working it until the GEAR SAFE annunciation was illuminated. He confirmed gear extension by seeing it in the engine nacelle mirror. He landed, but during the rollout the right main landing gear collapsed. The right wing was scraped, and the aileron and flap were damaged and had to be replaced. In addition, the right main gear pushrod was bent and had pushed against and bent the support web in the wheel well. Further examination of the landing gear revealed many parts worn and beyond their service life.
Probable cause: Total failure of the landing gear retraction/extension assembly. Contributing factors in this accident were worn parts in the landing gear retraction/extension assembly, and mechanical binding of the extension assembly.
For more information: NTSB.gov