N12WT

On September 13, 1997, about 1640 eastern daylight time, a Cessna 411, registered to a private individual, experienced a collapse of the left main landing gear while taxiing off the runway at the Williston Municipal Airport, Williston, Florida. The airplane was substantially damaged and the commercial-rated pilot and one passenger were not injured. The flight originated about 10 minutes earlier form the Ocala Regional/Jim Taylor Field Airport, Ocala, Florida.

The pilot stated that after landing on runway 22 while attempting to turn off the runway onto taxiway A, the left main landing gear collapsed. According to a private pilot-rated witness, the airplane was traveling "a little fast" when the pilot attempted to turn onto the taxiway. Review of the airport layout revealed an approximate 130-degree change in direction to the right from the runway centerline to the centerline of Taxiway A.

The damage was initially reported the day of the occurrence as minor; however, a subsequent detailed inspection revealed spar damage to the left wing. Postaccident examination of the left main landing gear revealed that the side brace lock attaching bolt Part No. AN25-38A, was failed.

Metallurgical examination of the failed bolt revealed that it failed due to shear. No evidence of preexisting cracks or corrosion was noted. Hardness tests were performed at three portions on the grip portion of the bolt which revealed values of 28.8, 28.9 and 30.0 RH C respectively. Review of the Military Handbook Identification Markings For Fasteners, Bolts, Screws, Studs, Nuts, and Rivets, revealed that based on the bolt head configuration and markings, the specified RH: C values are between 26-32.

Review of the maintenance records revealed that the bolt had been replaced at the last annual inspection which was accomplished on September 1, 1997. The airplane had accumulated 3.0 hours since the inspection at the time of the failure.

The airplane minus the retained hardware was released to Mr. Dave Lucas of Dave Lucas International on December 11, 1997. The retained hardware was also released to Mr. Lucas on December 19, 1997.