# NTSB SEA92LA191: Helio H-391B, N4431U, Edmonds, WA, August 26, 1992

- Type: NTSB accident investigation
- Classification: Accident · No injuries · Limited investigation · Final report
- Date: August 25, 1992, 20:40 local (Aug 26, 1992, 03:40 UTC)
- Place: Edmonds, WA
- Coordinates: 47.800739, -122.370223 (estimated)
- Nearby events: https://openairdocs.org/map.md?lat=47.8007&lon=-122.3702&mi=10
- Phase of flight: [Enroute](https://openairdocs.org/ntsb-phases/400) (OpenAirDocs' grouping)
- Highest injury: No injuries
- Injuries: 1 uninjured
- Status: Completed, report August 31, 1993
- Report: Approved by Office Director
- NTSB case key (mKey): 42888
- NTSB case page: https://web.ntsb.gov/investigations/?ntsbnumber=SEA92LA191
- NTSB report (PDF, downloads): https://data.ntsb.gov/carol-repgen/api/Aviation/ReportMain/GenerateNewestReport/42888/pdf
- Page: https://openairdocs.org/ntsb/SEA92LA191

## 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.

## Sequence of events

In NTSB's coding before 2008 (https://www.ntsb.gov/GILS/Documents/codman.pdf).

- Loss of engine power, cruise
  - engine assembly,valve,exhaust - seized (cause)
- Forced landing, descent - emergency
- Ditching, descent - emergency
- Nose over, landing - flare/touchdown
  - terrain condition - water (cause)

## Analysis

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.

## Aircraft

- Registration: [N4431U](https://openairdocs.org/aircraft/N4431U), registered now, S/N 091 (OpenAirDocs)
- Reported make and model: HELIO H-391B
- Registry model: [Helio H-391B](https://openairdocs.org/model/helio-h-391b) (registry code 4300106) (OpenAirDocs)
- Category: Airplane
- Serial number: 091
- Airframe hours: 2371
- Engines: LYCOMING GO-435 260 horsepower reciprocating
- Damage: Destroyed
- Flight: Personal, Part 91
- Operator: Brown, Christopher K.
- Registered owner: Brown, Christopher K.
- Airworthiness certificate: Standard, Normal
- Last inspection: Annual, March 26, 1992, 30 hours before
- Departed: FRH, FRIDAY HARBOR, WA
- Destination: BFI, SEATTLE, WA

## Flight crew

As NTSB recorded them. NTSB leaves out names.

- Pilot; age 31; airline transport; airplane ratings: single-engine land, single-engine sea, multi-engine land; instrument ratings: airplane; medical: class 1, valid medical--no waivers/lim.; seat: left; flight hours: 3,000 total, 190 in this make and model, 2,500 as pilot in command, 30 in the last 90 days, 15 in the last 30 days, 2 in the last 24 hours

## Weather

- Conditions: Visual (VMC), Night/dark
- Wind: 350° at 4 knots
- Visibility: 75 statute miles
- Lowest ceiling: none
- Temperature: 72 °F, dew point 50 °F
- Altimeter: 30.00 inHg
- Observed at: PAE, 4 nm away

## FAA reports on this event (1)

The FAA's own accident and incident reports, matched to the aircraft by N-number and date (OpenAirDocs).

- [Accident 19920825050879A](https://openairdocs.org/incident/19920825050879A), Aug 25, 1992: Helio H391B, Everett, WA, Destroyed. Lost partial power. Unable reach airport. Ditched in bay. NR4 exhaust valve was seized in open position.

## Other investigations on N4431U (2)

From the NTSB's public API. Aircraft are matched to registry aircraft by N-number and event date, checked against the reported serial number, make and model; the registry's history has gaps, so older matches can be wrong. Compare the reported make and model.

- [NTSB CEN25LA325](https://openairdocs.org/ntsb/CEN25LA325), Aug 18, 2025: Helio H-391B (N4431U), Monroe, MI, substantial damage. Probable cause: The pilot’s failure to maintain directional control during the landing roll with a crosswind.
- [NTSB SEA84LA026](https://openairdocs.org/ntsb/SEA84LA026), Nov 19, 1983: Helio H-391B (N4431U), Hood River, OR, substantial damage

From the NTSB's public API. Aircraft are matched to registry aircraft by N-number and event date, checked against the reported serial number, make and model; the registry's history has gaps, so older matches can be wrong. Compare the reported make and model.

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