EMMONAK, AK, USA
N4105D
Piper PA-31-350
The airline transport certificated pilot was landing a twin engine airplane on a rough, gravel runway that contained potholes. The commuter flight had just departed a similar, rough runway. During the landing roll, the airplane rolled down the runway for about 600 feet. The right main landing gear wheel then rotated about 90 degrees in its landing gear strut housing, and slid along the surface of the gravel runway for several hundred feet. The lower landing gear strut and wheel then broke away from the upper strut housing. The right wing settled onto the runway. The right propeller tips, and the trailing edge of the right flap were damaged. The right wing attach points for the landing gear were not damaged. Upon inspection of the airplane, a torque link, installed on the right main landing gear strut, was found fractured at the outer pivot bolt hole. An metallurgical examination of the torque link revealed a fracture through the pivot point of the link with features typical of overstress separation. No evidence of preexisting conditions, such as crack arrest marks, or corrosion damage was found.
On September 14, 2000, about 1910 Alaska daylight time, a Piper PA-31-350 airplane, N4105D, sustained substantial damage during landing at Emmonak, Alaska. The airplane was being operated as Flight 166 on a visual flight rules (VFR) scheduled domestic flight under Title 14, CFR Part 135, when the accident occurred. The airplane was operated by Grant Aviation Inc., Anchorage, Alaska. The airline transport certificated pilot, and the three passengers, were not injured. Visual meteorological conditions prevailed. VFR company flight following procedures were in effect. The flight originated at the Alakanuk Airport, Alakanuk, Alaska, at 1900. During a telephone conversation with the National Transportation Safety Board (NTSB) investigator-in-charge (IIC), on September 14, 2000, the company's vice president for airline operations reported that the runway surface at Alakanuk is rough with several potholes. The runway at Emmonak is also rough with several potholes. When the pilot landed at Emmonak, the airplane rolled down the runway for about 600 feet. The right main landing gear wheel then rotated about 90 degrees in its landing gear strut housing, and slid along the surface of the gravel runway for several hundred feet. The lower landing gear strut and wheel then broke away from the upper strut housing. The right wing settled onto the runway. The right propeller tips, and the trailing edge of the right flap were damaged. The right wing attach points for the landing gear were not damaged. Upon inspection of the airplane, a torque link, installed on the right main landing gear strut, was found fractured at the outer pivot bolt hole. The vice president said that the loss of the torque link allowed the right landing gear wheel to rotate within the upper landing gear strut housing. On September 25, 2000, the director of maintenance for the company reported that the airplane received damage to the aft fuselage bulkhead, and the leading edge of the right horizontal stabilizer. Additionally, the leading edge of the right wing was damaged when it struck a runway light fixture. The fractured torque link was sent to the National Transportation Safety Board's Materials Laboratory for examination. The examination revealed a fracture through the pivot point of the link with features typical of overstress separation. No evidence of preexisting conditions, such as crack arrest marks, or corrosion damage was found.
The pilot's continued operation of the airplane on unsuitable terrain, and the subsequent failure of the main landing gear torque link. Factors in the accident were rough and uneven runways, and inadequate surveillance of airport facilities/runway conditions by company management.
Source: NTSB Aviation Accident Database
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