N75LE

On May 22, 1993, at 2205 Alaska daylight time, a wheel equipped Cessna 185 airplane, N75LE, registered to and operated by the Pilot-in-Command, lost its right main gear and dragged its wing during the take off at Barrow, Alaska. The personal flight, operating under 14 CFR Part 91, was departing Barrow and the destination was Fairbanks, Alaska. Instrument meteorological conditions prevailed and a visual flight rules flight plan was filed. The flight was operating on a Special VFR clearance. The Pilot-in-Command, the sole occupant, was not injured and the airplane was substantially damaged.

According to the Pilot-in-Command, the wind was blowing from 050 degrees at 20 to 22 knots. he was taking off on runway 06. He applied throttle and during the acceleration, the right main wheel and axle separated from the gear leg. The nose struck the ground and the right main gear leg separated from the gear box. The wing then struck the ground.

The failed components were analyzed at the NTSB Materials Laboratory Division. The examination disclosed a large discolored region indicative of a large crack existing in the gear for a period of time. Fractographic examination showed a small fatigue crack and most of the region was indicative of high stress propagation. According to the Metallurgist, the large discolored area shows that the fracture arrested itself for a period of time allowing considerable oxide to form on the fracture surface.

The examination further showed damage to the corner of the chamfered hole where the fatigue crack initiated. The Metallurgist stated; "The corner appeared to be damage from an external source with the bolt removed, which provided the initiation area for the fatigue. Once again the characteristics of the fatigue appeared to be linked to high stress initiation and propagation and not necessarily to a defect alone such as small localized damage."