TALKEETNA, AK, USA
N185DG
Cessna A185F
During takeoff from a glacier off airport landing site, the right landing gear leg and ski separated from the airplane and both wings contacted the snow. Postaccident inspection revealed multiple site fatigue cracks at both upper wheel attachment bolt holes on the right landing gear leg. The airplane was routinely used for off airport landings on both wheels and skis. The airplane had accumulated 6,561 hours in operation at the time of the accident. No life limit (hours or cycles) exists for Cessna 185 landing gear legs. The only inspection for cracks is a visual inspection for general condition performed at 100 hour and annual intervals. This inspection does not require removal of the wheels/skis, nor does it require removal of any paint coatings prior to inspection.
On June 16, 1998, at 1215 Alaska daylight time, a wheel/ski equipped Cessna A185F airplane, N185DG, sustained substantial damage during takeoff from the 6,900 feet msl level of the Kahiltna Glacier, 50 miles northwest of Talkeetna, Alaska. The commercial pilot and the two passengers were not injured. The flight was operated under 14 CFR Part 135 by Douglas Geeting Aviation, Inc., of Talkeetna, as an on demand charter transporting mountain climbers from the Kahiltna Glacier to Talkeetna. Visual meteorological conditions prevailed at the time of the accident, and a VFR flight plan was filed. The pilot reported to the NTSB Investigator-In-Charge during a telephone interview that during his landing roll on the glacier he heard a "bang." He stated that he inspected the airplane and skis, and found no damage. During acceleration for takeoff from the glacier, after reaching 45 knots, the right ski separated from the airplane, the airplane swerved right, and both wings contacted the snow. Inspection of the fractured landing gear leg at the NTSB metallurgical laboratory on July 13, 1998, revealed multiple site fatigue cracking at the location of both landing gear attachment bolt holes. The airplane had accumulated 6,561 hours of operation at the time of the accident. There is no established life limit (hours or cycles) for Cessna 185 landing gear legs. There is no inspection requirement or procedure to detect fatigue cracks in the landing gear legs except for a visual inspection conducted during 100 hour and annual inspections. No nondestructive inspection technique requiring removal of wheels or skis, or removal of paint coatings to facilitate crack detection, had been specified by the manufacturer or FAA at the time of the accident.
The failure of the right main landing gear leg due to fatigue cracking. A factor associated with this accident is the inadequate inspection procedure specified by the manufacturer.
Source: NTSB Aviation Accident Database
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