DENALI NAT'L PK, AK, USA
N37932
PIPER J3
THE PRIVATE PILOT, ALASKA HUNTING GUIDE, WAS FLYING SUPPLIES TO CLIENTS IN THE FIELD LANDED ON REMOTE SNOW COVERED TUNDRA. UPON LANDING, THE RIGHT LANDING GEAR BOLT ATTACHMENT FITTING FAILED AND THE PLANE GROUND LOOPED. PREEXISTING FATIGUE WAS NOTED ON ATTACHMENT FITTING. THE FITTING IS NORMALLY ENCLOSED IN FABRIC RENDERING IT INACCESSIBLE FOR VISUAL INSPECTION.
On April 8, 1994, at 1645 Alaska daylight time, a ski equipped Piper J-3 Cub airplane, N37932, owned and operated by the pilot- in-command, crashed during landing at a remote landing site near the Tokositna River in the Denali National Park. The private certificated pilot, an Alaska registered hunting guide, the sole occupant, was not injured and the airplane sustained substantial damage. The business flight, conducted under 14 CFR Part 91 for the purpose of resupplying a hunting camp, last departed Trapper Creek, Alaska and the intended destination was the accident site. The pilot reported that at the time of the accident, visual meteorological conditions prevailed and there was no filed flight plan in effect. On the evening of April 09, 1994, the NTSB investigator-in-charge conducted a telephone interview with the pilot-in-command. The pilot reported that he was delayed in getting into the camp earlier in the day due to reduced visibility from a mixture of light rain and snow and there was poor contrast with the surrounding terrain which produced a flat light condition. Upon landing, was reported normal in every way, the right landing gear collapsed due to a gear bolt attachment failure. The right ski tipped forward and dug into the snow causing the right wing tip to collide with the snow resulting in a ground loop. The pilot forwarded the failed bolt attachment fitting to the NTSB investigator-in-charge. The fitting evidenced preexisting fatigue in the form of darkened discoloration along the fracture surface. The fitting is normally enclosed in fabric rendering it inaccessible for visual inspection.
THE FAILURE OF THE LANDING GEAR BOLT ATTACHMENT FITTING DUE TO FATIGUE.
Source: NTSB Aviation Accident Database
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