# NTSB SEA91LA109: Bell 47G-3B-1, N73903, Malott, WA, May 19, 1991

- Type: NTSB accident investigation
- Classification: Accident · No injuries · Limited investigation · Final report
- Date: May 19, 1991, 09:21 local (16:21 UTC)
- Place: Malott, WA
- Coordinates: 48.299365, -119.770637 (estimated)
- Nearby events: https://openairdocs.org/map.md?lat=48.2994&lon=-119.7706&mi=10
- Phase of flight: [Maneuvering](https://openairdocs.org/ntsb-phases/450) (OpenAirDocs' grouping)
- Highest injury: No injuries
- Injuries: 1 uninjured
- Status: Completed, report May 27, 1993
- Report: Approved by Office Director
- NTSB case key (mKey): 41433
- NTSB case page: https://web.ntsb.gov/investigations/?ntsbnumber=SEA91LA109
- NTSB report (PDF, downloads): https://data.ntsb.gov/carol-repgen/api/Aviation/ReportMain/GenerateNewestReport/41433/pdf
- Page: https://openairdocs.org/ntsb/SEA91LA109

## Probable cause

AN UNDETERMINED FAILURE OF THE FUEL PUMP CASING RESULTING IN AN IN FLIGHT FIRE AND LOSS OF ENGINE POWER.

## Sequence of events

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

- Loss of engine power(total) - mech failure/malf, maneuvering
  - fuel system,pump - undetermined (cause)
- Fire, maneuvering
- In flight collision with object, descent - emergency
  - object - tree(s)

## Analysis

DURING AN AERIAL APPLICATION FLIGHT, THE ENGINE SUDDENLY LOST POWER.  THE PILOT TRIED TO MANEUVER TO AN OPEN AREA, HOWEVER, THE HELICOPTER COLLIDED WITH TREES.  POST CRASH INVESTIGATION REVEALED THAT THE HELICOPTER EXPERIENCED AN IN FLIGHT FIRE.  IT WAS FOUND THAT A SECTION OF THE AUXILIARY FUEL PUMP CASING BROKE AWAY IN THE AREA WHERE THE FUEL LINE FITTING SCREWS INTO THE PUMP.  DUE TO FIRE DAMAGE, USEFUL FACTURE TOPOGRAPHY TO DETERMINE THE MODE OF FAILURE WAS DESTROYED.

## Aircraft

- Registration: [N73903](https://openairdocs.org/aircraft/N73903), registered now, S/N 2883 (OpenAirDocs)
- Reported make and model: BELL 47G-3B-1
- Registry model: [Bell 47G-3B-1](https://openairdocs.org/model/bell-47g-3b-1) (registry code 1181028) (OpenAirDocs)
- Registry engine: [Lycoming TVO-435-GIA](https://openairdocs.org/engine/lycoming-tvo-435-gia) (registry code 41526, turbo-prop) (OpenAirDocs)
- Category: Helicopter
- Serial number: 2883
- Engines: LYCOMING TVO-435-A1A 260 horsepower reciprocating
- Damage: Destroyed
- Fire: In-Flight
- Flight: Aerial application, Part 137
- Operator: Cascade Helicopter
- Registered owner: Cascade Helicopter

## Flight crew

As NTSB recorded them. NTSB leaves out names.

- Pilot; age 46; commercial; airplane ratings: single-engine land; medical: class 2, valid medical--no waivers/lim.; flight hours: 2,974 total, 1,150 in this make and model, 2,924 as pilot in command, 96 in the last 90 days, 49 in the last 30 days, 5 in the last 24 hours

## Weather

- Conditions: Visual (VMC), Day
- Wind: calm
- Visibility: 12 statute miles
- Lowest ceiling: 2,500 ft overcast
- Temperature: -0 °F, dew point -0 °F

## 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 19910519016509A](https://openairdocs.org/incident/19910519016509A), May 19, 1991: Bell 47G3B1, Malott, WA, Destroyed. Lost power on spray run. Struck trees landing. Had inflight fire. Aux fuel pump casing broke at fuel line fitting.

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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