# NTSB LAX84LA494: Hiller UH12ET, N9278Z, Yuma, AZ, September 25, 1984

- Type: NTSB accident investigation
- Classification: Accident · Serious injuries · Limited investigation · Final report
- Date: September 25, 1984, 06:01 local (13:01 UTC)
- Place: Yuma, AZ
- Location: 32.7253° N, 114.6244° W: Placed by OpenAirDocs: center of Yuma, AZ, within about 6 miles (OpenAirDocs)
- Nearby events: https://openairdocs.org/map.md?lat=32.7253&lon=-114.6244&mi=10
- Phase of flight: [Maneuvering](https://openairdocs.org/ntsb-phases/450) (OpenAirDocs' grouping)
- Highest injury: Serious injuries
- Injuries: 1 serious
- Status: Completed
- Report: Approved by Office Director
- NTSB case key (mKey): 24410
- NTSB case page: https://web.ntsb.gov/investigations/?ntsbnumber=LAX84LA494
- NTSB report (PDF, downloads): https://data.ntsb.gov/carol-repgen/api/Aviation/ReportMain/GenerateNewestReport/24410/pdf
- Page: https://openairdocs.org/ntsb/LAX84LA494

## Sequence of events

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

- Airframe/component/system failure/malfunction, maneuvering - aerial application
  - maintenance,recordkeeping - improper, company maintenance personnel (contributing factor)
  - maintenance,compliance with ad - not performed, company maintenance personnel (cause)
  - rotor system,main rotor blade spar - corroded (cause)
  - rotor system,main rotor blade spar - failure,total (cause)
- Loss of control - in flight, descent - uncontrolled
  - low pass - intentional, pilot in command
  - remedial action - not possible, pilot in command
- In flight collision with terrain/water, descent - uncontrolled

## Analysis

THE PILOT STATED THAT HE WAS CARRYING A LOAD OF PESTICIDE FOR APPLICATION ON A BROCCOLI FIELD. THE AIRCRAFT WAS IN LEVEL FLIGHT, APPROXIMATELY 4 TO 8 FEET AGL WHEN IT BECAME UNCONTROLLABLE AND IMPACTED THE GROUND. THE AIRCRAFT WAS CONSUMED BY A POST CRASH FIRE. EXAMINATION OF THE AIRCRAFT AFTER THE ACCIDENT REVEALED THAT ONE OF THE TWO MAIN ROTOR BLADES HAD SEPARATED IN-FLIGHT. EXAMINATION OF THE SEPARATED ROTOR BLADE REVEALED A FATIGUE TYPE FRACTURE OF THE MAIN ROTOR BLADE SPAR TUBE THROUGH THE OUTBOARD RETENTION BOLT HOLES. THE FAILED MAIN ROTOR BLADE SPAR BORE EVIDENCE OF CORROSION. THE MAIN ROTOR BLADE CUFF WAS THE SUBJECT OF AN AIRWORTHINESS DIRECTIVE THAT ACCORDING TO THE AIRCRAFT LOGBOOKS HAD BEEN COMPLIED WITH AS REQUIRED. THE LAST THREE LOGBOOK NOTATIONS, DOCUMENTING COMPLIANCE WITH THE AD, WERE ENTERED AFTER THE ACCIDENT.

## Aircraft

- Registration: [N9278Z](https://openairdocs.org/deregistered/N9278Z-2014-11-24), registration cancelled 2014-11-24, S/N 1819, built 1965 (OpenAirDocs)
- Reported make and model: HILLER UH12ET
- Registry model: [Hiller UH-12E](https://openairdocs.org/model/hiller-uh-12e) (registry code 4360122) (OpenAirDocs)
- Registry engine: [Lycoming VO-540 series](https://openairdocs.org/engine/lycoming-vo-540-series) (registry code 41534, reciprocating) (OpenAirDocs)
- Category: Helicopter
- Serial number: 1819
- Airframe hours: 6376
- Engines: ALLISON 250-C20B 425 horsepower turbo shaft
- Damage: Destroyed
- Fire: On-Ground
- Flight: Aerial application, Part 137
- Registered owner: Valley Sprayers/Dusters Inc.
- Airworthiness certificate: Special, Restricted (Special)
- Last inspection: Annual, February 29, 1984, 304 hours before
- Departed: YUMA, AZ

## Flight crew

As NTSB recorded them. NTSB leaves out names.

- Pilot; age 35; commercial; airplane ratings: single-engine land; instrument ratings: airplane; medical: class 2, valid medical--no waivers/lim.; seat: center; flight hours: 6,428 total, 2,100 in this make and model, 6,428 as pilot in command, 210 in the last 90 days, 100 in the last 30 days, 6 in the last 24 hours

## Weather

- Conditions: Visual (VMC), Dawn
- Wind: 50° at 7 knots
- Visibility: 7 statute miles
- Lowest ceiling: 5,000 ft broken
- Temperature: 77 °F, dew point 57 °F
- Altimeter: 29.00 inHg
- Observed at: YUM, 8 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 19840925074369A](https://openairdocs.org/incident/19840925074369A), Sep 25, 1984: Hiller UH12E, Yuma, AZ, Destroyed. Lost control during spraying. Control rotor blade spar tube failed. Corrosion found. Service bulletin not performed

## Other investigations on N9278Z (2)

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 LAX80DUJ91](https://openairdocs.org/ntsb/LAX80DUJ91), Jul 31, 1980: Hiller Acft UH-12E (N9278Z), Sommerton, AZ, substantial damage
- [NTSB LAX76DUJ80](https://openairdocs.org/ntsb/LAX76DUJ80), May 11, 1976: Hiller Acft UH-12E (N9278Z), Somerton, AZ, 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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