Skip to content

SEA92LA029

1991-10-28 · BILLINGS, Montana, United States · None · 1 aircraft · Status: Completed

Aircraft involved

Probable cause & findings

THE UNLATCHING AND SUBSEQUENT OPENING INFLIGHT OF THE LEFT-REAR ENGINE COWL DOOR. A FACTOR CONTRIBUTING TO THE ACCIDENT WAS THE FAILURE OF COMPANY MAINTENANCE PERSONNEL TO EXECUTE THE MANUFACTURER'S SERVICE BULLETIN.

Factual narrative

SHORTLY AFTER THE COMPANY INITIATED ABORT OF THE MEDEVAC FLIGHT, THE FLIGHT CREW OF THE AEROSPATIALE AS355 FELT A SHUDDER WHICH THEY ATTRIBUTED TO GUSTY WIND CONDITIONS. UPON LANDING AT BILLINGS INTERNATIONAL AIRPORT, MONTANA, A PORTION OF THE LEFT-REAR ENGINE COWL DOOR WAS FOUND TO BE SEPARATED, ALONG WITH DAMAGE TO THE MAIN ROTOR BLADES NECESSITATING REPLACEMENT OF THE BLADES. THE CREW HAD PREVIOUSLY NOTIFIED COMPANY PERSONNEL OF THE COWL DOOR LATCH PROBLEM AND HAD PREFLIGHTED THE COWL PRIOR TO THE ACCIDENT FLIGHT. THE MANUFACTURER WAS AWARE OF THE PROBLEM AND HAD ISSUED A RELEVANT SERVICE BULLETIN. THE SERVICE BULLETIN HAD NOT BEEN IMPLEMENTED ON THE ACCIDENT AIRCRAFT. Source: NTSB Aviation Accident Database (Pre-2008 Archive) Retrieved: 2026-02-12

Verbatim from NTSB's published report. Source file NTSB_1991_SEA92LA029.txt. Findings + structured fields enriched from FAA avall.mdb. Full investigation docket on data.ntsb.gov ↗.

Search this event elsewhere

External sources are reported, not agency: signal that something happened, not fact about what happened.

Related research

Matched on aircraft type or causal vocabulary (maintenance). All research papers