CEN23LA208

The conventional geared airplane’s right main landing gear collapsed during landing and the airplane’s left wing sustained substantial damage. The pilot reported that the flight instructor performed the final landing and that the landing was very hard. The flight instructor reported that he landed on centerline and as the airplane was rolling out the right main landing gear collapsed. He noted that there were no brakes in the right seat pilot station where he was located. Metallurgical examination of the failed landing gear revealed corrosion on the inside of the main landing gear tube in the area where it was welded to the wheel axle. The corrosion progressively thinned the leg tube walls over time and caused pitting and microcracking on the tube interior. The combination of missing material, pitting, and microcracks led to an overstress fracture of the leg at this location on the final landing, which led to two other subsequent overstress fractures. The Federal Aviation Administration issued a special airworthiness information bulletin (SAIB), CE-17-14, to alert operators of this and other similar model airplanes of the need to inspect and address corrosion issues on main landing gear. The SAIB recommended following the procedures of the Don Luscombe Aviation History Foundation Service Recommendation No. 4, dated Jan. 22, 1996, which provided instructions for installing a drain hole in the lower portion of the leg, performing repetitive inspections of the gear legs for corrosion, and cleaning and sealing the gear legs’ internal surfaces. Compliance with the SAIB is not mandatory. Limited maintenance records were available during the investigation; however, the most recent annual inspection entry did not indicate that the landing gear were inspected for corrosion. The fractured main landing gear did not have drain holes as noted in the service recommendation, indicating that that procedures in the service recommendation had not been performed. Based on the available evidence the accident was the result of failure of the right main landing gear leg due to weakening from prolonged internal corrosion of the landing gear tube, which weakened the leg.

On May 18, 2023, about 1800 mountain daylight time, a Luscombe 8E, N2515K, was substantially damaged when it was involved in an accident at the Cortez Municipal Airport (CEZ), Cortez, Colorado. The pilot and the flight instructor were not injured. The airplane was operated as a Title 14 Code of Federal Regulations (CFR) Part 91 personal flight. The airplane was recently purchased by the pilot and delivered to CEZ by the flight instructor. After delivery, the pilot and flight instructor conducted flights over several days to familiarize the pilot with the airplane. According to the pilot, during the accident flight he conducted several landings without incident. The final takeoff and landing were conducted with the flight instructor manipulating the airplane’s flight controls. He said that the final landing was “very hard.” The flight instructor reported that he landed on the runway centerline and as the airplane was rolling out, the right main landing gear collapsed. He noted that the right seat position, where he was seated, did not have brakes installed. During the landing, the right main landing gear collapsed. The airplane’s left wing was substantially damaged during the landing. The failed right main landing gear was examined by the National Transportation Safety Board Materials Laboratory. Examination of the failed landing gear revealed corrosion on the inside of the main landing gear tube in the area where it was welded to the wheel axle. The corrosion progressively thinned the leg tube walls over time and caused pitting and microcracking on the tube interior. The combination of missing material, pitting, and microcracks led to an overstress fracture of the leg at this location on the final landing, which led to two other subsequent overstress fractures. The tube thickness near the fracture had thinned from 0.040 inches to 0.025 inches. On June 5, 2017, the Federal Aviation Administration (FAA) issued a special airworthiness information bulletin (SAIB), CE-17-14, to alert operators of several models of JGS Properties LLC and Luscombe airplanes, including the model 8E, of a need for inspection to detect and correct corrosion inside the main landing gear legs. According to the bulletin, internal surface treatment and regular inspection of the lower legs may help mitigate the corrosion related gear failures. Compliance with a FAA SAIB is not mandatory for 14 CFR Part 91 operations. The FAA recommended that owners and operators of the affected airplanes follow the inspection procedures outlined in The Don Luscombe Aviation History Foundation Service Recommendation No. 4, dated Jan. 22, 1996, which provided instructions for installing a drain hole in the lower portion of the leg, performing repetitive inspections of the gear legs for corrosion, and cleaning and sealing the gear legs’ internal surfaces. The accident airplane did not appear to have a drain hole in this portion of the lower leg. The FAA also urged using X ray or ultrasoundinspection methods on the leg-to-axle joint to detect internal rust during initial or follow-on inspections of the gear leg. Limited maintenance records were available during the investigation; however, the most recent annual inspection entry did not indicate that the landing gear were inspected for corrosion. The fractured main landing gear did not have drain holes as noted in the service recommendation.