# NTSB DEN86LA016: Hiller UH-12E, N400AH, Vernal, UT, November 1, 1985

- Type: NTSB accident investigation
- Classification: Accident · No injuries · Limited investigation · Final report
- Date: November 1, 1985, 16:30 local (23:30 UTC)
- Place: Vernal, UT
- Coordinates: 40.550823, -109.56919 (estimated)
- Nearby events: https://openairdocs.org/map.md?lat=40.5508&lon=-109.5692&mi=10
- Phase of flight: [Enroute](https://openairdocs.org/ntsb-phases/400) (OpenAirDocs' grouping)
- Highest injury: No injuries
- Injuries: 2 uninjured
- Status: Completed
- Report: Approved by Office Director
- NTSB case key (mKey): 16879
- NTSB case page: https://web.ntsb.gov/investigations/?ntsbnumber=DEN86LA016
- NTSB report (PDF, downloads): https://data.ntsb.gov/carol-repgen/api/Aviation/ReportMain/GenerateNewestReport/16879/pdf
- Page: https://openairdocs.org/ntsb/DEN86LA016

## Sequence of events

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

- Airframe/component/system failure/malfunction, cruise
  - exhaust system,turbocharger - failure,total (cause)
- Forced landing, cruise
  - terrain condition - mountainous/hilly (contributing factor)
- Hard landing, landing
  - landing gear,skid assembly - buckled
  - rotor system,main rotor blade - bent
  - rotor system,tail rotor blade - bent
  - rotor drive system,tail rotor drive shaft - separation

## Analysis

THE PLT STATED HE HAD JUST DEPARTED A SITE LOCATED ON TOP OF A MOUNTAIN, WHICH IS APPROXIMATELY 12,200 FT MSL. THE PILOT SAID 30 SECONDS LATER, THE HELICOPTER LOST PARTIAL POWER. REQUIRING HIM TO MAKE A FORCE LANDING. THE INSPECTION OF THE TURBOCHARGER REVEALED THE COMPRESSOR IMPELLER RETAINING NUT HAD BACKED OFF, ALLOWING THE COMPRESSOR IMPELLER TO CONTACT THE COMPRESSOR SHROUD AND LEADING TO THE SEIZURE OF THE IMPELLER. THIS RESULTED IN THE FAILURE OF THE TURBOCHARGER.

## Aircraft

- Registration: [N400AH](https://openairdocs.org/deregistered/N400AH-2003-04-22), registration cancelled 2003-04-22, S/N 1177, built 1975 (OpenAirDocs)
- Reported make and model: HILLER UH-12E
- Registry model: [Hiller UH-12E](https://openairdocs.org/model/hiller-uh-12e) (registry code 4360122) (OpenAirDocs)
- Registry engine: [Lycoming TI0-540 series](https://openairdocs.org/engine/lycoming-ti0-540-series) (registry code 41533, turbo-prop) (OpenAirDocs)
- Category: Helicopter
- Serial number: 1177
- Airframe hours: 6334
- Engines: LYCOMING TIVO-540-A2A 315 horsepower reciprocating
- Damage: Substantial damage
- Flight: Part 135
- Registered owner: Calvin D. Hunt
- Airworthiness certificate: Standard, Normal
- Last inspection: Annual, October 6, 1985, 14 hours before
- Airport: VEL, Vernal

## Flight crew

As NTSB recorded them. NTSB leaves out names.

- Pilot; age 32; commercial, private; airplane ratings: single-engine land; medical: class 2, valid medical--no waivers/lim.; seat: left; flight hours: 4,641 total, 4,260 in this make and model, 4,200 as pilot in command, 30 in the last 90 days

## Weather

- Conditions: Visual (VMC), Day
- Wind: calm
- Visibility: 46 statute miles
- Lowest ceiling: none
- Temperature: 50 °F, dew point 21 °F
- Altimeter: 30.00 inHg
- Observed at: VEL, 39 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 19851101055799A](https://openairdocs.org/incident/19851101055799A), Nov 1, 1985: Hiller UH12E, Vernal, UT, Substantial damage. Turbocharger failed, impeller lodged on shroud after retaining nut backed out. Turbocharger installation on STC.

## Other investigations on N400AH (4)

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 DEN88LA046](https://openairdocs.org/ntsb/DEN88LA046), Jan 2, 1988: Hiller UH-12E (N400AH), Vernal, UT, substantial damage
- [NTSB DEN83LA204](https://openairdocs.org/ntsb/DEN83LA204), Aug 31, 1983: Hiller UH-12E (N400AH), Manning, ND, substantial damage
- [NTSB DEN81DTE08](https://openairdocs.org/ntsb/DEN81DTE08), Nov 17, 1981: Hiller UH12E (N400AH), Craig, CO, substantial damage
- [NTSB DEN79FTE64](https://openairdocs.org/ntsb/DEN79FTE64), Jul 24, 1979: Hiller 12E (N400AH), Longmont, CO, 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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