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DEN86LA166

1986-06-19 · ONIDA, South Dakota, United States · None · 1 aircraft · Status: Completed

Airport 98D

Aircraft involved

Factual narrative

THE PLT REPORTED A PARTIAL LOSS OF PWR OCCURRED MOMENTARILY BEFORE LIFTOFF. THE TAKEOFF WAS CONTINUED AND ONCE AIRBORNE THE PWR LOSS REOCCURRED. THE LOAD WAS DUMPED, HOWEVER, THE ACFT IMPACTED TREES APRX 1 MILE FROM THE ARPT AS SUFFICIENT ALT COULD NOT BE MAINTAINED. POST ACCIDENT INSPECTION REVEALED THE #2 AND #8 CYLINDER INTAKE VALVES WERE TULIPED AND WOULD NOT CLOSE. THE #2, #6 AND #8 OUTLET TOWER BLOCKS ON THE MAGNETO WERE CROSSFIRING WHICH RESULTED IN PRE-IGNITION TO THOSE CYLINDERS. Source: NTSB Aviation Accident Database (Pre-2008 Archive) Retrieved: 2026-02-12

Verbatim from NTSB's published report. Source file NTSB_1986_DEN86LA166.txt. Findings + structured fields enriched from FAA avall.mdb. Full investigation docket on data.ntsb.gov ↗.

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