LAX83LA427

1983-09-08 · KAILUA-KONA, Hawaii, United States · Serious · 1 aircraft · Status: Completed

Airport KOA

Aircraft involved

N2990F Beech H18S Serious

Factual narrative

ABOUT 1 MIN AFTER TAKEOFF, BETWEEN 400-500 FT MSL & DURING THE FIRST POWER REDUCTION, THE RIGHT ENG BACKFIRED. FOLLOWINGSOME MORE VIOLENT BACKFIRES THE RPM WENT TO ZERO. THE RIGHT ENG WAS RESTARTED BUT THE SAME RESULT OCCURRED. THE PLT ATTEMPTED TO FEATHER THE RIGHT PROP BUT TO NO AVAIL. THE ACFT WAS THEN DELIBERATELY DITCHED TO AVOID AN OUTCROPPING OF LAVA. THE ACFT CAME TO REST IN ABOUT 25-30 FT OF WATER. ENG INSPECTION REVEALED THAT THE #2 CYLINDER EXHAUST ROCKER ARM SHAFT, P/N45937, WAS MISSING. DRIVE TRAIN CONTINUITY WAS ESTABLISHED WITH THE EXCEPTION OF THE #2 EXHAUST VALVE. CENTRIFUGAL STOPS PREVENT FEATHERING OF THE PROP BELOW AN ENG SPEED OF 500 RPM. Source: NTSB Aviation Accident Database (Pre-2008 Archive) Retrieved: 2026-02-12

Verbatim from NTSB's published report. Source file NTSB_1983_LAX83LA427.txt. Findings + structured fields enriched from FAA avall.mdb. Full investigation docket on data.ntsb.gov ↗.

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