SEA98LA064 · Bell 47G-3B-1
Bell 47G-3B-1 · Accident: loss of engine power during initial climb
From an unrecorded airport to Arlington Municipal Airport (AWO)
Event
- NTSB case
- SEA98LA064
- 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
Bell 47G-3B-1
- Aircraft type
- Bell 47
- Category
- Helicopter
- 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
- N80SD
- Operator
- Helfenberger, Daniel, E. · private individual
- Onboard fatalities
- Unknown
- Route
- From not recordedTo Arlington Municipal Airport (AWO), Arlington, 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
- Initial climb
- 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
- Also codedOther events the NTSB coded in the sequence, such as a wire strike after a loss of power. Flight Findings uses them for its kinds of event. Glossary
- Fuel contamination; Tree(s)
- 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
- Fluid, fuel › Contamination, other than water
- Fuel system, carburetor › Flow restricted
- Material inadequate, improper
Approximate · Coordinates as recorded by the NTSB; no uncertainty radius is established.
NTSB narrative
During initial climb immediately after takeoff the helicopter lost power. The pilot attempted to maneuver to a clear area, but struck trees during the descent. Post crash examination revealed no mechanical malfunction with either the engine or carburetor although the carburetor had been subjected to a post crash fire and its fuel metering orifices could not be bench tested. Fuel samples taken from the helicopter's fuel tank prior to the accident, and from the fueling hose from the portable fuel truck were examined by a fuels testing lab and were found to contain 1,2-Benzenedicarboxylic acid, bis(2-ethylhexyl) ester. The pre-accident aircraft fuel sample, which contained a submersed glob of clear substance similar to that observed by the pilot seeping from the cut ends of the fueling hose, was tested. The test revealed that the 'soluble gum' consisted of 1,2-Benzenedicarboxylic acid, bis(2-ethylhexyl) ester' and that nearly 100% of the gum was soluble in the fuel. The operator was advised by the local distributor of the 'Versicon' hose that the hose was acceptable for use with aviation fuels. Specifications provided by the manufacturer of the hose, HBD Industries, provided a note which stated 'Not recommended for the variety of unleaded gas existing presently.'
Probable cause
Fuel contamination and subsequent carburetor fuel flow restriction initiated by the use of an improper material (incorrect fuel hose). A factor was the trees.
Verbatim NTSB analysis and probable cause from the NTSB dataset
Sources
NTSB record SEA98LA064
- Event ID
- 20001211X09960
- Case number
- SEA98LA064
- 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 1998-04-20.
- API snapshot SHA-256: b53e939c77070a97c30217aacfd23ac7caa8553b7f3265ac5027d6344e33fabb; retrieved 2026-09-22T17:52:13.484Z.