ERA09LA540

During landing, the right main landing gear touched first, followed by the left main gear which was accompanied by an audible “thump.” The left main gear collapsed and the airplane veered off the edge of the runway. The left main landing gear attachment fitting was examined at the NTSB materials laboratory and no preexisting fractures were noted. The steel fitting was constructed from tubing and bar stock, and was powder-coated after fabrication. Examination revealed that the fitting failed due to overstress midway along the angled tube portion and that the fractures were consistent with bending loads experienced during landing and taxiing. The examination further revealed that the wall thickness was less than the manufacturer's specifications, and that the interior of the angled tube had been counter-bored prior to the powered coating and final assembly at the factory. Review of the NTSB database revealed that there were two additional accidents that occurred with identical damage incurred; in all instances, the parts failed from an overstress fracture that initiated in approximately the same location.

On September 13, 2009, about 0915 eastern daylight time, a special light sport Flight Design GMBH CTSW, N466CT, was substantially damaged following landing and a landing gear collapse at Gettysburg Regional Airport (W05), Gettysburg, Pennsylvania. The certificated private pilot was not injured. Visual meteorological conditions prevailed for the local personal flight, which originated at W05 at 0830, and was conducted under the provisions of Title 14 Code of Federal Regulations Part 91. In a telephone interview, the pilot stated that he had completed some “air work” in the local flying area prior to returning for landing on runway 24 at W05. While landing on the runway, with a right crosswind at 5 to 6 knots, and the flaps set at 15 degrees, the right main landing gear touched first. When the left main gear touched down, the pilot heard a “thump,” the left gear collapsed, and the airplane veered off the side of the runway. When asked to describe the landing on a scale of 1 to 10, the pilot described it as a “5” and said that the left main landing gear’s contact with the runway was similar to that of the right. A review of Federal Aviation Administration (FAA) airman records revealed that pilot held a private pilot certificate with a rating for airplane single engine land. His most recent FAA third class medical certificate was issued October 9, 1985. The pilot’s most recent flight review was completed on April 18, 2008. The pilot reported 190 total hours of flight experience, with 70 hours in the accident airplane make and model. According to FAA and maintenance records, the airplane was manufactured in 2007 and had accrued 90 total aircraft hours. Its most recent conditional inspection was completed August 29, 2009, at 82 total aircraft hours. The 0916 weather observation at Carroll County Airport (DMW), Westminster, Maryland, 19 miles southeast of the accident site, included clear skies and winds from 230 degrees at 6 knots. The visibility was 10 miles. The temperature was 24 degrees Celsius (C) and the dew point was 14 degrees C. The altimeter setting was 30.01 inches of mercury. Examination of the airplane at the scene by an FAA inspector revealed separation of the left main landing gear and substantial damage to the fuselage at the attach point. The gear was retained for examination at the National Transportation Safety Board (NTSB) materials laboratory in Washington, D.C. Data was downloaded from the Dynon Avionics D100 primary flight display for examination at the NTSB recorders laboratory, Washington, D.C. According to Dynon Avionics, the software version installed on the accident airplane "did not record data;" therefore, no accident flight data was recovered from the unit. The left main landing gear attachment fitting was examined at the NTSB materials laboratory, and no preexisting fractures were noted. The fitting was manufactured as an all-steel weldment constructed from tubing and bar stock, which was powder-coated afterfabrication. Examination revealed that the fitting failed due to overstress midway along the angled tube portion, and that the fractures were consistent with bending loads experienced during landing and taxiing. Examination further revealed that the wall thickness was less than the manufacturer's specification, and that the interior of the angled tube had been "counterbored" prior to powerdercoating and final assembly. Examination of the NTSB database revealed two additional accidents with identical damage and that in all three instances, the parts failed from an overstress fracture that initiated in approximately the same location.