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Atlas / NTSB / DEN89IA124

NTSB CAROL · Event

Event DEN89IA124

1989-05-24 DENVER, Colorado, United States Airport · KDEN None 1 aircraft Status: Completed

Aircraft involved

Probable cause & findings

FAILURE OF THE LEFT MAIN LANDING GEAR FORWARD TRUNNION BEARING SUPPORT FITTING DUE TO A CRACK INITIATING AT THE FORWARD EDGE OF THE BORE AND PROPAGATING BY INTERGRANULAR STRESS CORROSION INTO THE BORE SURFACE THAT RESULTED IN AN EVENTUAL DUCTILE FRACTURE.

Factual narrative

THE LEFT MAIN LANDING GEAR COLLAPSED AS THE AIRCRAFT WAS PULLED FORWARD SLIGHTLY TO BRING THE NOSEWHEEL OFF THE CHOCKS PRIOR TO PUSHBACK. INSPECTION DISCLOSED A FRACTURE OF THE FORWARD TRUNNION BEARING SUPPORT FITTING (P/N 65-16206-11) AND HEAVY SURFACE CORROSION. MICROSCOPIC EXAMINATION DISCLOSED EXTENSIVE INTERGRANULAR STRESS CORROSION, AND A CRACK THAT HAD DEVELOPED 0.1 INCHES INBOARD FROM THE FORWARD EDGE OF THE BORE, WHICH HAD PROPAGATED APPROXIMATELY 2.1 INCHES AFT INTO THE BORE SURFACE. THE FINAL FRACTURE RESULTED FROM DUCTILE SEPARATION. Source: NTSB Aviation Accident Database (Pre-2008 Archive) Retrieved: 2026-02-12

Verbatim from NTSB's published report. Source file NTSB_1989_DEN89IA124.txt. Findings + structured fields enriched from FAA avall.mdb. Full investigation docket on data.ntsb.gov ↗.