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MIA92LA167

1992-08-26 · MIAMI, Florida, United States · Serious · 1 aircraft · Status: Completed

Airport MIA

Aircraft involved

Probable cause & findings

FAILURE (SHORT) OF A DIODE LOCATED INSIDE A TRANSFORMER WHICH IS LOCATED IN THE NO. 1 GENERATOR CONTROL UNIT.

Factual narrative

WHILE AWAITING TAKEOFF CLEARANCE, THE CAPT STATED THAT HE OBSERVED A FLASH OF LIGHT & SMELLED SMOKE. HE INITIATED THE PAX EVACUATION CHECKLIST & ALL PAX EVACUATED THE ACFT. EXAM OF THE ACFT BY COMPANY MAINT PERSONNEL REVEALED THAT THE NO. 1 GENERATOR CONTROL UNIT (GCU) LOCATED BEHIND THE FIRST OFFICER'S SEAT EXPERIENCED INTERNAL FAILURE. THE GCU WAS REMOVED FOR FURTHER EXAMINATION. EXAM OF THE UNIT REVEALED THAT A DIODE LOCATED INSIDE A TRANSFORMER WAS SHORTED, WHICH OVERHEATED THE TRANSFORMER & PRODUCED THE SMOKE. ACCORDING TO BOEING, THERE HAVE BEEN 12 SIMILAR OCCURRENCES. Source: NTSB Aviation Accident Database (Pre-2008 Archive) Retrieved: 2026-02-12

Verbatim from NTSB's published report. Source file NTSB_1992_MIA92LA167.txt. Findings + structured fields enriched from FAA avall.mdb. Full investigation docket on data.ntsb.gov ↗.