# NTSB LAX90DXQ04: Bell UH-1B, N64789, Bieber, CA, August 14, 1990

- Type: NTSB accident investigation
- Classification: Accident · Serious injuries · Final report
- Date: August 13, 1990, 17:58 local (Aug 14, 1990, 00:58 UTC)
- Place: Bieber, CA
- Coordinates: 41.060199, -121.109634 (estimated)
- Nearby events: https://openairdocs.org/map.md?lat=41.0602&lon=-121.1096&mi=10
- Phase of flight: [Approach](https://openairdocs.org/ntsb-phases/500) (OpenAirDocs' grouping)
- Highest injury: Serious injuries
- Injuries: 1 serious
- Status: Completed, report December 8, 1992
- Report: Approved by Office Director
- NTSB case key (mKey): 26591
- NTSB case page: https://web.ntsb.gov/investigations/?ntsbnumber=LAX90DXQ04
- NTSB report (PDF, downloads): https://data.ntsb.gov/carol-repgen/api/Aviation/ReportMain/GenerateNewestReport/26591/pdf
- Page: https://openairdocs.org/ntsb/LAX90DXQ04

## Probable cause

THE PILOT'S FAILURE TO MAINTAIN AIRCRAFT CONTROL WHEN INTENTIONALLY SLOWING HIS AIRCRAFT TO OFF LOAD WATER ON FIRE. CONTRIBUTING TO THE ACCIDENT WAS THE PILOT'S FAILURE TO ARM AND RELEASE THE EXTERNAL LOAD.

## Sequence of events

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

- Loss of control - in flight, approach
  - terrain condition - high terrain
  - airspeed - not maintained, pilot in command (cause)
  - directional control - not maintained, pilot in command (cause)
- In flight collision with terrain/water, descent - uncontrolled
  - object - tree(s)
  - load jettison - attempted

## Analysis

THE PILOT WAS FLYING A FIRE FIGHTING MISSION AND WAS APPROACHING SOUTHERLY ASCENDING TERRAIN FROM THE EAST. THE AIRCRAFT APPROACHED THE TERRAIN AND SLOWED TO MAKE A WATER DROP. AS IT SLOWED THE TAIL TURNED TO THE LEFT AND THE HELICOPTER LOST ALTITUDE AND SETTLED INTO THE TREES. THE PILOT HEARD THE LOW RPM AUDIO AND SAW THE LOW RPM WARNING LIGHT. HE ATTEMPTED TO RELEASE THE WATER LOAD. EXAMINATION OF THE ENGINE AND ENGINE COMPONENTS REVEALED NO EVIDENCE OF A MALFUNCTION OR FAILURE. THE TEMPERATURE REPORTEDLY WAS BETWEEN 82 TO 86 DEGREES F WITH THE WIND FROM THE NORTH AT 5 TO 8 KNOTS.

## Aircraft

- Registration: [N64789](https://openairdocs.org/deregistered/N64789-1998-03-04), registration cancelled 1998-03-04, S/N 624598 (OpenAirDocs)
- Reported make and model: BELL UH-1B
- Registry model: [Bell UH-1B](https://openairdocs.org/model/bell-uh-1b) (registry code 1181410) (OpenAirDocs)
- Category: Helicopter
- Serial number: 62-4598
- Airframe hours: 5220
- Engines: LYCOMING T53-L11 1100 horsepower turbo shaft
- Damage: Substantial damage
- Flight: Public aircraft, Part 133
- Operator: Intermountain Air Services
- Registered owner: Carson Leasing & Equity Inc.
- Airworthiness certificate: Special, Restricted (Special)
- Last inspection: Annual, December 15, 1989, 46 hours before

## Flight crew

As NTSB recorded them. NTSB leaves out names.

- Pilot; age 50; commercial; medical: class 2, valid medical--w/ waivers/lim; seat: right; flight hours: 20,000 total

## Weather

- Conditions: Visual (VMC), Day
- Wind: 270° at 8 knots
- Visibility: 6 statute miles
- Lowest ceiling: none
- Temperature: 86 °F, dew point 43 °F
- Altimeter: 29.00 inHg
- Observed at: RBL, 92 nm away

## Other investigations on N64789 (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 LAX86FVA10](https://openairdocs.org/ntsb/LAX86FVA10), Jun 30, 1986: Bell UH-1B (N64789), Le Grand, CA, 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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