# NTSB SEA86LA089: Hiller 12E, N87595, Walla Walla, WA, March 30, 1986

- Type: NTSB accident investigation
- Classification: Accident · No injuries · Limited investigation · Final report
- Date: March 29, 1986, 17:15 local (Mar 30, 1986, 01:15 UTC)
- Place: Walla Walla, WA
- Coordinates: 46.109066, -118.299949 (estimated)
- Nearby events: https://openairdocs.org/map.md?lat=46.1091&lon=-118.2999&mi=10
- Phase of flight: [Enroute](https://openairdocs.org/ntsb-phases/400) (OpenAirDocs' grouping)
- Highest injury: No injuries
- Injuries: 1 uninjured
- Status: Completed
- Report: Approved by Office Director
- NTSB case key (mKey): 40378
- NTSB case page: https://web.ntsb.gov/investigations/?ntsbnumber=SEA86LA089
- NTSB report (PDF, downloads): https://data.ntsb.gov/carol-repgen/api/Aviation/ReportMain/GenerateNewestReport/40378/pdf
- Page: https://openairdocs.org/ntsb/SEA86LA089

## Sequence of events

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

- Airframe/component/system failure/malfunction, cruise
  - propeller system/accessories,planetary gear - failure,total (cause)
  - maintenance,overhaul - improper, pilot in command (cause)
- Forced landing, cruise
- Hard landing, landing - flare/touchdown
- Fire, landing - flare/touchdown

## Analysis

A CATASTROPHIC FAILURE OF THE PLANETARY GEAR OF THE TRANSMISSION OCCURRED ABOUT 51 FLIGHT HOURS AFTER OVERHAUL. DURING FORCED LANDING A HARD LANDING OCCURRED SEVERING THE TAIL BOOM. A FIRE THEN ERUPTED.

## Aircraft

- Registration: [N87595](https://openairdocs.org/deregistered/N87595-2013-02-20), registration cancelled 2013-02-20, S/N 1184, built 1960 (OpenAirDocs)
- Reported make and model: HILLER 12E
- Registry model: [Hiller UH-12D](https://openairdocs.org/model/hiller-uh-12d) (registry code 4360118) (OpenAirDocs)
- Registry engine: [Lycoming VO-435 series](https://openairdocs.org/engine/lycoming-vo-435-series) (registry code 41525, reciprocating) (OpenAirDocs)
- Category: Helicopter
- Serial number: 1184
- Airframe hours: 8315
- Engines: LYCOMING TIVO-540-A2A 315 horsepower reciprocating
- Damage: Destroyed
- Fire: On-Ground
- Flight: Aerial application, Part 137
- Registered owner: Blue Mountain Aviation, Inc.
- Airworthiness certificate: Special, Restricted (Special)
- Last inspection: 100 hour, March 28, 1986
- Departed: WALLA WALLA, WA

## Flight crew

As NTSB recorded them. NTSB leaves out names.

- Pilot; age 41; commercial; airplane ratings: single-engine land, multi-engine land; instrument ratings: airplane; medical: class 2, valid medical--no waivers/lim.; seat: front; flight hours: 3,393 total, 541 in this make and model, 3,226 as pilot in command, 61 in the last 90 days, 7 in the last 24 hours

## Weather

- Conditions: Visual (VMC), Day
- Wind: calm
- Visibility: 30 statute miles
- Lowest ceiling: none
- Temperature: 61 °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 19860329037559A](https://openairdocs.org/incident/19860329037559A), Mar 29, 1986: Hiller UH12D, Walla Walla, WA, Destroyed. Transmission planetary gear failed. Hit ground tail low on turn back to landing sight. Destroyed by fire.

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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