Cordova, AK, USA
N402ET
Cessna 402C
The airline transport certificated pilot was landing the retractable gear airplane on a hard surfaced runway at the conclusion of an air taxi cargo flight. During the landing roll, the pilot reported that the airplane veered to the right, and he was unable to maintain directional control. The right main landing gear subsequently collapsed, resulting in substantial damage to the right wing spar. Inspection by the NTSB investigator-in-charge and company maintenance personnel, disclosed that the right main landing gear scissor link/strut became disconnected, which allowed the right main wheel assembly to turn sideways and overload the gear leg. Examination of the linkage revealed that the bolt securing the scissors/linkage had pulled through the washer adjacent to the scissor bushing opening, and ultimately through the bushing, disconnecting the linkage. The manufacturer of the airplane issued Service Letter ME-83-37, dated November 23, 1983, that recommended the original equipment outer main landing gear scissors link washers be replaced with larger, more robust washers for "...improved service life and main landing gear alignment retention." The operator had not complied with the nonmandatory service letter, and the airplane was operated with the smaller washers.
On February 20, 2007, about 0820 Alaska standard time, a wheel-equipped Cessna 402C airplane, N402ET, operated by Arctic Circle Air, Anchorage, Alaska, under Title 14, CFR Part 135 as an on-demand cargo flight, sustained substantial damage following a malfunction of the right main landing gear and loss of directional control while landing at the Cordova Merle K. Smith Airport, Cordova, Alaska. The solo airline transport certificated pilot was not injured. The flight departed Anchorage about 0717, and the destination was Cordova. Visual meteorological conditions prevailed, and a VFR company flight plan was in effect. During several discussions with the NTSB investigator-in-charge on February 20 and the following week, the company director of operations and director of maintenance disclosed that the pilot reported the airplane veered to the right shortly after touchdown on runway 09, and that he was unable to maintain directional control. The airplane's right main landing gear subsequently collapsed and trailed rearward, under the right engine nacelle. The director of maintenance reported to the NTSB IIC during an on-site inspection of the airplane by the IIC at the company's maintenance facility in Anchorage on February 27, that the right wing rear spar had received structural damage during the landing gear collapse, and that it may not be economically feasible to complete the necessary repairs. The director of maintenance indicated that his inspection of the right main landing gear disclosed that the landing gear scissors link became disconnected during the accident landing, which allowed the right main landing gear wheel assembly to turn sideways and overload the gear structure, pulling it from its mounting on the wing spar. The director of maintenance noted that it appeared that the small washer on the scissor link, which is only slightly larger than the scissors bushing opening, had failed, which resulted in the scissor link bushing pulling through and disconnecting the linkage. Cessna Service Information Letter ME83-37, dated November 23, 1983, recommends that the two outer main landing gear scissors link washers be replaced with larger, more robust washers for "...improved service life and main gear alignment retention." The service letter modification was not mandatory, and the accident airplane's main landing gear had not been modified with the larger washers.
The failure of the right main landing gear linkage during the landing roll, which resulted in a loss of directional control and the collapse of the right main landing gear. A factor associated with the accident was the failure of company maintenance personnel to comply with a maintenance service letter issued by the airplane manufacturer.
Source: NTSB Aviation Accident Database
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