# NTSB LAX99LA237: Hiller UH-12ET, N7173F, Williams, CA, June 30, 1999

- Type: NTSB accident investigation
- Classification: Accident · No injuries · Limited investigation · Final report
- Date: June 30, 1999, 07:00 local (14:00 UTC)
- Place: Williams, CA
- Coordinates: 39.270099, -122.050498 (estimated)
- Nearby events: https://openairdocs.org/map.md?lat=39.2701&lon=-122.0505&mi=10
- Phase of flight: [Maneuvering](https://openairdocs.org/ntsb-phases/450) (OpenAirDocs' grouping)
- Highest injury: No injuries
- Injuries: 1 uninjured
- Status: Completed, report November 22, 2000
- Report: Approved by Office Director
- NTSB case key (mKey): 47019
- NTSB case page: https://web.ntsb.gov/investigations/?ntsbnumber=LAX99LA237
- NTSB report (PDF, downloads): https://data.ntsb.gov/carol-repgen/api/Aviation/ReportMain/GenerateNewestReport/47019/pdf
- Page: https://openairdocs.org/ntsb/LAX99LA237

## Probable cause

The pilot's inadequate preflight planning and verification that fuel was available for the intended flight.  A factor was the fuel quantity false indication.

## Sequence of events

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

- Loss of engine power, maneuvering - aerial application
  - fuel system,fuel quantity float/sensor - false indication (contributing factor)
  - refueling - not verified, pilot in command (cause)
  - preflight planning/preparation - improper, pilot in command (cause)
- Forced landing, descent - emergency
  - terrain condition - none suitable
- Hard landing, emergency landing
  - misc rotorcraft,tail boom - separation

## Analysis

While spraying a rice field the engine suddenly quit.  The pilot force landed in the field severing the tail boom.  The pilot reported the turbine powered helicopter had been fueled the day before the accident, however, he did not visually confirm it.  The aircraft had only flown 0.5 hours during this flight. Examination of the fuel system revealed a broken wire in the fuel quantity indicating system.  According to the maintenance manual for this helicopter, the open circuit caused by the wire breakage will cause a fuel quantity indication of 34 gallons when the tank is empty.

## Factual narrative

On June 30, 1999, about 0700 hours Pacific daylight time, a Hiller UH-12ET, N7173F, was substantially damaged during a forced landing in a rice field at Williams, California.  The commercial pilot was not injured.  The helicopter was being operated by Pacific Valley Aviation of Colusa, California, under the provisions of 14 CFR Part 137.  A company visual flight plan was filed.  Visual meteorological conditions prevailed for the local area agricultural flight, which originated near the field to be sprayed about 0630.

The pilot stated that the engine abruptly quit while spraying the rice field and the forced landing resulted in the severing of the tail boom.  He reported the turbine powered helicopter had been fueled the day before the accident, however, he did not visually confirm it.  He had only flown 0.5 hours during this flight.

Subsequent examination of the fuel system revealed a broken wire at the aft liquidometer.  According to the UH-12E maintenance manual, an open circuit between pin A of the fuel gauge and pin C of the aft tank liquidometer would cause the gauge to indicate 34 gallons when the tank is empty.

The pilot/operator failed to file a Safety Board Pilot Operator Accident Report, form 6120.1/2.

## Aircraft

- Registration: [N7173F](https://openairdocs.org/aircraft/N7173F), registered now, S/N 2011 (OpenAirDocs)
- Reported make and model: Hiller UH-12ET
- Registry model: [Hiller UH-12E](https://openairdocs.org/model/hiller-uh-12e) (registry code 4360122) (OpenAirDocs)
- Registry engine: [Allison 250-C20 series](https://openairdocs.org/engine/allison-250-c20-series) (registry code 03020, turbo-prop) (OpenAirDocs)
- Category: Helicopter
- Serial number: 2011
- Airframe hours: 12083
- Engines: Allison 250-C20B 305 horsepower turbo shaft
- Damage: Substantial damage
- Flight: Aerial application, Part 137
- Operator: Pacific Valley Aviation
- Registered owner: James Miller
- Airworthiness certificate: Special, Restricted (Special)
- Departed: NONE, COLUSA, CA
- Destination: NONE, CA

## Flight crew

As NTSB recorded them. NTSB leaves out names.

- Pilot; age 52; commercial; airplane ratings: single-engine land; medical: class 2, valid medical--w/ waivers/lim; seat: left; flight hours: 18,000 total

## Weather

- Conditions: Visual (VMC), Day
- Visibility: 20 statute miles
- Lowest ceiling: none
- Temperature: 79 °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 19990630007949A](https://openairdocs.org/incident/19990630007949A), Jun 30, 1999: Hiller UH12E, Williams, CA, Substantial damage. 1959 Hiller UH-12E helicopter engine failed during aerial application, and the acft crashed and sustained substantial damage. (.4)while spraying a rice field…

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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