# NTSB LAX91LA128: Bell 47G-5A, N59403, Farmington, CA, March 10, 1991

- Type: NTSB accident investigation
- Classification: Accident · No injuries · Limited investigation · Final report
- Date: March 9, 1991, 16:30 local (Mar 10, 1991, 00:30 UTC)
- Place: Farmington, CA
- Coordinates: 37.960483, -120.870277 (estimated)
- Nearby events: https://openairdocs.org/map.md?lat=37.9605&lon=-120.8703&mi=10
- Phase of flight: [Maneuvering](https://openairdocs.org/ntsb-phases/450) (OpenAirDocs' grouping)
- Highest injury: No injuries
- Injuries: 1 uninjured
- Status: Completed, report March 31, 1993
- Report: Approved by Office Director
- NTSB case key (mKey): 27136
- NTSB case page: https://web.ntsb.gov/investigations/?ntsbnumber=LAX91LA128
- NTSB report (PDF, downloads): https://data.ntsb.gov/carol-repgen/api/Aviation/ReportMain/GenerateNewestReport/27136/pdf
- Page: https://openairdocs.org/ntsb/LAX91LA128

## Probable cause

THE CONTAMINATION OF THE ENGINE INDUCTION AIR FILTER.  SOFT TERRAIN DURING THE TOUCHDOWN WAS A FACTOR IN THE ACCIDENT.

## Sequence of events

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

- Loss of engine power(partial) - nonmechanical, maneuvering - turn to reverse direction
  - induction air control,air filter/screen - contamination (cause)
- Forced landing, descent - emergency
- In flight collision with terrain/water, landing - flare/touchdown
  - terrain condition - soft (contributing factor)

## Analysis

THE ENGINE POWER REDUCED DURING A PROCEDURE TURNAROUND AS THE AIRCRAFT WAS DISPENSING LIQUID FERTILIZER. THE HELICOPTER SETTLED INTO SOFT TERRAIN AND THE MAIN ROTOR BLADE SEVERED THE TAIL BOOM. THE HELICOPTER THEN IMPACTED THE GROUND. EXAMINATION OF THE ENGINE'S AIR FILTER DISCLOSED EVIDENCE OF LIQUID FERTILIZER CLOGGING THE FILTER.

## Aircraft

- Registration: [N59403](https://openairdocs.org/aircraft/N59403), registered now, S/N 25140, built 1973 (OpenAirDocs)
- Reported make and model: BELL 47G-5A
- Registry model: [Bell 47G-5A](https://openairdocs.org/model/bell-47g-5a) (registry code 1181034) (OpenAirDocs)
- Registry engine: [Lycoming VO-435 series](https://openairdocs.org/engine/lycoming-vo-435-series) (registry code 41525, reciprocating) (OpenAirDocs)
- Category: Helicopter
- Serial number: 25140
- Engines: LYCOMING VO-435-81A 220 horsepower reciprocating
- Damage: Substantial damage
- Flight: Aerial application, Part 137
- Operator: Ag-Air, Inc.
- Airworthiness certificate: Special, Restricted (Special)
- Last inspection: Unknown, January 2, 2000

## Flight crew

As NTSB recorded them. NTSB leaves out names.

- Pilot; age 45; commercial; airplane ratings: single-engine land; instrument ratings: airplane; medical: class 2, valid medical--no waivers/lim.; flight hours: 10,000 total, 10,000 as pilot in command, 20 in the last 90 days, 15 in the last 30 days, 3 in the last 24 hours

## Weather

- Conditions: Visual (VMC), Day
- Wind: calm
- Visibility: 10 statute miles
- Lowest ceiling: none
- 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 19910309004819A](https://openairdocs.org/incident/19910309004819A), Mar 9, 1991: Bell 47G5A, Farmington, CA, Substantial damage. Flew into liquid fertilizer during a turn from spray run. Lost engine RPM settled to ground. Air intake was fouled.

## Other investigations on N59403 (1)

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 DEN05CA078](https://openairdocs.org/ntsb/DEN05CA078), May 19, 2005: Bell 47G-5A (N59403), Brush, CO, substantial damage. Probable cause: The pilot's failure to maintain clearance from the truck trailer during takeoff. A factor contributing to this accident was the truck trailer.

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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