SEA92LA191 · Helio H-391B
Helio H-391B · Accident: loss of engine power en route
From FRH · Friday Harbor, WA to King County International Airport - Boeing Field (BFI)
Event
- NTSB case
- SEA92LA191
- Event typeAccident: someone killed or seriously injured, or the aircraft substantially damaged (NTSB definition). Incident: an occurrence that affected or could have affected safety, short of that. Glossary
- Accident
- InvestigationHow far the investigation had got when the record was published: preliminary, ongoing, final or completed. Unknown where the source does not say. Glossary
- Completed
- API-reported fatalities
- 0 · all aircraft and ground
- Ground fatalities
- 0
- OperationWhat kind of flying it was, grouped by the rules it flew under: airline (US Part 121), air taxi and commuter (Part 135), general aviation (Part 91 and similar), military or government. Glossary
- General aviation
- WeatherVisual meteorological conditions (VMC): good enough to fly by looking outside. Instrument conditions (IMC): cloud or low visibility, flying by instruments. Glossary
- Visual Meteorological Cond
Helio H-391B
- Aircraft type
- Helio H-391
- Category
- Airplane
- RegistrationThe aircraft's tail number, such as N12345 or G-ABCD. Registrations are reissued, so the same one years apart can be a different aircraft. Glossary
- N4431U
- Operator
- Brown, Christopher K. · private individual
- Onboard fatalities
- Unknown
- Route
- From FRH · Friday Harbor, WATo King County International Airport - Boeing Field (BFI), Seattle, WA
- Aircraft age
- Not recorded
- Flight rulesThe regulations the flight operated under: in the US, Part 91 (general aviation), Part 121 (airlines), Part 135 (air taxi and commuter) and others; for flights abroad, the NTSB's coarser commercial or non-commercial code. Glossary
- Part 91: General Aviation
- Phase of flightThe stage of the flight when things started to go wrong: standing, taxi, takeoff, initial climb, en route, maneuvering, approach or landing. Glossary
- En route · cruise
- First occurrenceThe single coded event the NTSB judges best describes what happened (records from 2008 on). Older records name the first occurrence in the sequence instead. Glossary
- Loss of engine power
- DamageDestroyed: beyond practical repair. Substantial: damage that affects the structure, performance or handling and normally needs major repair. Minor: less than that. Glossary
- Destroyed
Cause areas
- Engine assembly, valve, exhaust › Seized
- Terrain condition › Water
Approximate · Coordinates as recorded by the NTSB; no uncertainty radius is established.
NTSB narrative
THE PILOT INCREASED POWER TO INITIATE A CLIMB AND THE ENGINE PARTIALLY LOST POWER. HE DITCHED THE ACFT IN PUGET SOUND WHEN HE WAS UNABLE TO REACH AN AIRPORT OR THE SHORE FOR AN EMERGENCY LANDING. THE ACFT NOSED OVER ON TOUCHDOWN IN THE WATER. AN EXAM OF THE ENGINE AFTER THE ACCIDENT REVEALED THE NO 4 EXHAUST VALVE WAS SEIZED IN THE OPEN POSITION.
Probable cause
THE PARTIAL LOSS OF ENGINE POWER WHEN AN EXHAUST VALVE SEIZED IN THE OPEN POSITION AND THE WATER WHERE THE PILOT WAS FORCED TO LAND, WHICH RESULTED IN AN ACFT NOSE OVER ON TOUCHDOWN.
Verbatim NTSB analysis and probable cause from the NTSB dataset
Sources
NTSB record SEA92LA191
- Event ID
- 20001211X15548
- Case number
- SEA92LA191
- Dataset
- historical-pre2008
- Source SHA-256
- 89e2df6d848e7ab3b42e7d7c7a03ff403303057a26ca04c95b3ea67201c3ce74
Source notes (4)
- Unreviewed is an editorial label, not an investigation status. API-sourced is not report-checked or human-reviewed. Explicit event totals are used without summing aircraft injury tables; onboard allocation is withheld. Unknown values remain unknown. The operation category is mapped from the NTSB-reported FAR part and has not been reviewed.
- Filled from the NTSB case API where the bulk record had no value: local date, investigation status. Values present in the bulk record are kept.
- The date is the local date; the NTSB stores the UTC date 1992-08-26.
- API snapshot SHA-256: 9d3300a40af6a109aa6b1ba01936ba7525a886ff8a721708474fc7e9c82f038f; retrieved 2026-09-23T02:43:09.713Z.