On August 5, 1987, a Bellanca 7GCBC (registration N222WY) was involved in an aviation accident near North Plains, OR. Investigators recorded the probable cause as: Left main landing gear axle failed due to a fatigue crack that originated at the edge of a circumferential weld. This summary draws on records from the U.S. National Transportation Safety Board (NTSB) historical archive.
During a crosswind landing, the left main landing gear axle failed after touchdown, causing the aircraft to pitch onto its nose and skid. Investigation revealed a fatigue crack at the axle's circumferential weld.
Incident Summary
The pilot reported that during a crosswind landing, the aircraft touched down on the right main gear. After rolling approximately 50 to 100 feet, the left main gear made contact with the runway. As the left wheel touched down, the left axle failed, causing the aircraft to pitch onto its nose. The aircraft then skidded on its nose for an additional 75 to 100 feet before coming to a stop.
Examination of the Axle
A post-incident examination of the failed left axle revealed that a fatigue crack had penetrated approximately 50% of its cross-sectional area before final overstress separation occurred. The crack had multiple origins at the edge of a circumferential weld on the axle.
Conclusion
The failure of the left main landing gear axle was attributed to a pre-existing fatigue crack that weakened the structure, leading to its separation under the loads experienced during the landing rollout.
Probable cause
Left main landing gear axle failed due to a fatigue crack that originated at the edge of a circumferential weld.