Cessna A185 N85CF accident near Illiamna, Alaska

Probable cause

The overstress fracture of the left main landing (MLG) gear axle attachment bolts and the subsequent separation of the left MLG wheel, which resulted in the pilot’s inability to control the airplane.

NTSB analysis

The commercial pilot reported that he made a normal approach and landing to an unimproved landing strip and that the left main landing gear (MLG) wheel assembly separated from the landing gear leg at the axle bolts during rollout. The gear leg then dug into the gravel landing surface, which resulted in a sudden left turn, ground loop, and subsequent substantial damage to the left wing, left aileron, and elevator. The pilot and the passenger stated that it did not feel as if the airplane hit anything during the landing rollout. The pilot also stated that the initiating event may have been a crosswind landing on a hard-surfaced runway with large tundra tires earlier in the week, during which he inadvertently "put a side load on the landing gear."

Postaccident examination of the left MLG axle assembly and bolts revealed that the left axle had separated from the landing gear leg due to a rearward overload event. The initial separation was due to the shearing of the forward bolt threads by tensile forces on the bolts, which was followed by the bending deformation of the aft bolts, consistent with a fore-to-aft overload.

Text from the NTSB. Open the NTSB docket for ANC16LA046 for the full record.