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CHI88FA110

1988-05-09 · CHICAGO, Illinois, United States · None · 1 aircraft · Status: Completed

Airport ORD

Aircraft involved

Probable cause & findings

FAILURE OF THE NUMBER THREE FLAP TRACK DUE TO STRESS CORROSION CRACKING. FACTORS CONTRIBUTING TO THIS FAILURE ARE INSUFFICIENT DESIGN OF THE MEMBER AND INADEQUATE INSPECTION AND MAINTENANCE PROCEDURES TO DETECT CRACKS BEFORE THEY PROPAGATE TO A CRITICAL LENGTH.

Factual narrative

THE ACFT WAS ON FINAL APPROACH TO CHICAGO O'HARE INTER'L AIRPORT WHEN A STRUCTURAL FAILURE OF THE NUMBER THREE FLAP TRACK OCCURRED. THE ACFT SUSTAINED SUBSTANTIAL DAMAGE TO THE LEFT WING, LEFT INBOARD FLAP ASSEMBLY, LEFT INBOARD SPOILERS AND SPOILER SUPPORT BEAM. THE PILOT EXPERIENCED SIGNIFICANT UNCOMMANDED ROLL AND YAW, BUT REGAINED CONTROL OF THE ACFT AND EXECUTED AN UNEVENTFUL LANDING. THE INVESTIGATION HAS REVEALED A HISTORY OF FLAP TRACK CRACKING PROBLEMS ASSOCIATED WITH STRESS CORROSION AND DESIGN INADEQUACY. A DESIGN CHANGE OF THE MEMBER WAS ACCOMPLISHED IN 1971 BY THE MANUFACTURER, BUT FLAP TRACKS OF THE EARLIER DESIGN WERE ALLOWED TO REMAIN IN SERVICE ON 239 AIRCRAFT. THE AIRWORTHINESS DIRECTIVES AND SERVICE BULLETINS APPLICABLE TO THIS PARTICULAR STRUCTURAL MEMBER ARE NOT ADEQUATE IN METHODOLOGY AND PERIODICITY TO ENSURE CRACK DETECTION, AND DO NOT REQUIRE INSPECTION FOR THE CAUSE OF THE CRACK-CORROSION PITS. Source: NTSB Aviation Accident Database (Pre-2008 Archive) Retrieved: 2026-02-12

Verbatim from NTSB's published report. Source file NTSB_1988_CHI88FA110.txt. Findings + structured fields enriched from FAA avall.mdb. Full investigation docket on data.ntsb.gov ↗.

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