# NTSB LAX90LA095: Bell 47B3, N11HU, Redlands, CA, February 16, 1990

- Type: NTSB accident investigation
- Classification: Accident · No injuries · Limited investigation · Final report
- Date: February 16, 1990, 06:30 local (14:30 UTC)
- Place: Redlands, CA
- Location: 34.0556° N, 117.1825° W: Placed by OpenAirDocs: center of Redlands, CA, within about 6 miles (OpenAirDocs)
- Nearby events: https://openairdocs.org/map.md?lat=34.0556&lon=-117.1825&mi=10
- Phase of flight: [Maneuvering](https://openairdocs.org/ntsb-phases/450) (OpenAirDocs' grouping)
- Highest injury: No injuries
- Injuries: 1 uninjured
- Status: Completed, report September 28, 1992
- Report: Approved by Office Director
- NTSB case key (mKey): 26737
- NTSB case page: https://web.ntsb.gov/investigations/?ntsbnumber=LAX90LA095
- NTSB report (PDF, downloads): https://data.ntsb.gov/carol-repgen/api/Aviation/ReportMain/GenerateNewestReport/26737/pdf
- Page: https://openairdocs.org/ntsb/LAX90LA095

## Probable cause

FAILURE OF THE PILOT TO USE CARBURETOR HEAT WHEN WARRENTED BY CONDITIONS.

## Sequence of events

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

- Loss of engine power(partial) - nonmechanical, maneuvering
  - fluid,fuel - improper (contributing factor)
  - weather condition - carburetor icing conditions (cause)
  - carburetor heat - not used, pilot in command (cause)
  - carburetor heat - not used, pilot in command (cause)
- In flight collision with object, descent
  - object - tree(s) (contributing factor)

## Analysis

THE OPERATOR BORROWED THE HELICOPTER FROM THE OWNER UNDER A VERBAL STIPULATION THAT AUTOMOTIVE FUEL WOULD NOT BE USED. THE ACCIDENT HELICOPTER WAS NOT APPROVED FOR AUTOMOTIVE GASOLINE UNDER THE PROVISIONS OF AN STC. HOWEVER, THE OPERATOR WAS KNOWN TO REFUEL HIS HELICOPTERS WITH AUTO GAS. THE PURPOSE OF THE FLIGHT WAS TO ERADICATE FROST FROM CITRUS TREES. AFTER REFUELING, THE HELICOPTER LOST POWER AND DESCENDED STRIKING WIRES AND TREES. THE OPERATOR DRAINED THE FUEL FROM THE HELICOPTER ON THE GROUND AND TRANSPORTED IT TO HIS FACILITY. THE ACCIDENT WAS REPORTED FOUR DAYS LATER. EXAMINATION OF THE FUEL SYSTEM REVEALED A SMALL QUANTITY OF FUEL WITH EVIDENCE OF AUTO GAS. LABORATORY ANALYSIS OF FUEL SAMPLE REVEALED SAMPLE HAD THE SAME AROMATIC QUALITIES AS AUTO GAS. ACCORDING TO THE FAA, THE ONSET OF CARBURETOR ICE WILL OCCUR QUICKER WITH AUTO GAS THAN WITH AVIATION FUEL. WEATHER CONDITIONS WERE CONDUCIVE TO FROST FORMING ON FRUIT TREES.

## Aircraft

- Registration: N11HU (not matched to a registry record)
- Reported make and model: Bell 47B3
- Category: Helicopter
- Serial number: 11
- Airframe hours: 12000
- Engines: FRANKLIN 6V4 200 C32 210 horsepower reciprocating
- Damage: Destroyed
- Flight: Business, Part 91
- Operator: Zimlock Helicopters
- Registered owner: Poulos, Randell B
- Airworthiness certificate: Standard, Utility; Standard, Normal
- Last inspection: Unknown, January 11, 1990, 70 hours before

## Flight crew

As NTSB recorded them. NTSB leaves out names.

- Pilot; age 32; private, commercial; airplane ratings: single-engine land; medical: class 2, unknown; seat: left

## Weather

- Conditions: Visual (VMC), Dawn
- Wind: calm
- Visibility: 20 statute miles
- Lowest ceiling: none
- Temperature: 34 °F, dew point 19 °F
- Altimeter: 30.00 inHg
- Observed at: SBD, 9 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 19900216002489A](https://openairdocs.org/incident/19900216002489A), Feb 16, 1990: Bell 47B3, Redlands, CA, Substantial damage. Engine rough and power loss on fruit tree frost run. Struck wires and trees. Possible carb ice. Using mogas no STC.

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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