# NTSB SEA84LA034: Hiller UH-12E, N4027K, Mapleton, OR, January 5, 1984

- Type: NTSB accident investigation
- Classification: Accident · Minor injuries · Limited investigation · Final report
- Date: January 5, 1984, 14:50 local (22:50 UTC)
- Place: Mapleton, OR
- Coordinates: 44.000392, -123.839065 (estimated)
- Nearby events: https://openairdocs.org/map.md?lat=44.0004&lon=-123.8391&mi=10
- Phase of flight: [Maneuvering](https://openairdocs.org/ntsb-phases/450) (OpenAirDocs' grouping)
- Highest injury: Minor injuries
- Injuries: 1 minor
- Status: Completed
- Report: Approved by Office Director
- NTSB case key (mKey): 39859
- NTSB case page: https://web.ntsb.gov/investigations/?ntsbnumber=SEA84LA034
- NTSB report (PDF, downloads): https://data.ntsb.gov/carol-repgen/api/Aviation/ReportMain/GenerateNewestReport/39859/pdf
- Page: https://openairdocs.org/ntsb/SEA84LA034

## Analysis

WHILE APPROACHING THE SPRAY AREA, THE ACFT WAS IN A LEVEL ATTITUDE AT 20 TO 25 MPH & ABOUT 100 FT AGL WHEN THE PLT HEARD A LOUD BANG & NOTED A LOSS OF POWER. HE ATTEMPTED AN AUTOROTATIVE LANDING. DURING TOUCHDOWN ON HILLY TERRAIN, THE ACFT ROLLED TO THE RIGHT & CAME TO REST INVERTED ON A STEEP SLOPE. A TEARDOWN OF THE ENG REVEALED THAT A SPUR ADAPTER GEARSHAFT, PN 6890482, & A COMPRESSOR COUPLING ADAPTER, PN 6871472, HAD FAILED. FAILURE OF THE SPUR ADAPTER GEARSHAFT WAS DUE TO FATIGUE WHICH ORIGINATED AT AN AREA OF HEAVY WEAR ON THE LOAD SIDE OF THE FORWARD SPLINES.

## Sequence of events

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

- Loss of engine power(total) - mech failure/malf, maneuvering - aerial application
  - turboshaft engine,gas generator turbine shaft - worn (cause)
  - turboshaft engine,gas generator turbine shaft - fatigue (cause)
- Forced landing, landing
  - autorotation - performed, pilot in command
- Roll over, landing - flare/touchdown
  - terrain condition - mountainous/hilly (contributing factor)

## Aircraft

- Registration: [N4027K](https://openairdocs.org/deregistered/N4027K-1989-11-03), registration cancelled 1989-11-03, S/N 5067 (OpenAirDocs)
- Reported make and model: HILLER UH-12E
- Registry model: [Hiller UH-12E](https://openairdocs.org/model/hiller-uh-12e) (registry code 4360122) (OpenAirDocs)
- Category: Helicopter
- Serial number: 5067
- Airframe hours: 2267
- Engines: ALLISON 250-C20B 305 horsepower turbo shaft
- Damage: Substantial damage
- Flight: Aerial application, Part 137
- Registered owner: Western Helicopters
- Airworthiness certificate: Special, Restricted (Special)
- Last inspection: 100 hour, January 3, 1984, 5 hours before

## Flight crew

As NTSB recorded them. NTSB leaves out names.

- Pilot; age 38; airline transport, commercial; airplane ratings: single-engine land, multi-engine land; instrument ratings: helicopter, airplane; medical: class 2, valid medical--no waivers/lim.; seat: left; flight hours: 5,675 total, 250 in this make and model, 5,427 as pilot in command, 102 in the last 90 days, 5 in the last 24 hours

## Weather

- Conditions: Visual (VMC), Day
- Wind: calm
- Visibility: 5 statute miles
- Lowest ceiling: none
- Temperature: 50 °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 19840105000059A](https://openairdocs.org/incident/19840105000059A), Jan 5, 1984: Hiller UH12E, Mapleton, OR, Substantial damage. Engine failed during spray run. Forced landing in hilly terrain. Spur coupling and compressor adapter had failed.

From the NTSB's public API. Aircraft are matched to registry aircraft by N-number and event date; the registry's history has gaps, so older matches can be wrong. Compare the reported make and model.

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