# NTSB DEN89LA084: Hiller UH-12E, N7411N, Golden, CO, March 9, 1989

- Type: NTSB accident investigation
- Classification: Accident · No injuries · Limited investigation · Final report
- Date: March 9, 1989, 14:55 local (21:55 UTC)
- Place: Golden, CO
- Coordinates: 39.730518, -105.199211 (estimated)
- Nearby events: https://openairdocs.org/map.md?lat=39.7305&lon=-105.1992&mi=10
- Phase of flight: [Maneuvering](https://openairdocs.org/ntsb-phases/450) (OpenAirDocs' grouping)
- Highest injury: No injuries
- Injuries: 2 uninjured
- Status: Completed, report April 24, 1990
- Report: Approved by Office Director
- NTSB case key (mKey): 17679
- NTSB case page: https://web.ntsb.gov/investigations/?ntsbnumber=DEN89LA084
- NTSB report (PDF, downloads): https://data.ntsb.gov/carol-repgen/api/Aviation/ReportMain/GenerateNewestReport/17679/pdf
- Page: https://openairdocs.org/ntsb/DEN89LA084

## Probable cause

IMPROPER IN-FLIGHT PLANNING/DECISION BY THE CFI WHICH RESULTED IN LOSS OF TAIL ROTOR EFFECTIVENESS AND LOSS OF DIRECTIONAL CONTROL. CONTRIBUTING FACTORS WERE HIGH DENSITY ALTITUDE, TAILWIND, AND ROUGH/UNEVEN TERRAIN.

## Sequence of events

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

- Loss of control - in flight, hover
  - in-flight planning/decision - improper, pilot in command(cfi) (cause)
  - weather condition - tailwind (contributing factor)
  - weather condition - high density altitude (contributing factor)
  - directional control - not maintained, pilot in command(cfi) (cause)
- Forced landing, descent - emergency
  - autorotation - attempted
- In flight collision with terrain/water, landing
  - terrain condition - rough/uneven (contributing factor)

## Analysis

THE INSTRUCTOR (CFI) & DUAL STUDENT WERE PRACTICING PINNACLE APCHS. THE CFI WAS FLYING THE HELICOPETER AS AN APCH WAS MADE TO A 6318' PINNACLE FROM THE SOUTHEAST. ACCORDING TO THE STUDENT, THE WIND WAS FROM THE EAST AT 8 TO 10 KTS. AS THE CFI FLEW TO A 4' HOVER, THERE WAS A LOSS OF TAIL ROTOR CONTROL & THE HELICOPTER BEGAN AN UNCOMMANDED RIGHT TURN. THE CFI MADE A HOVERING AUTOROTATION, BUT THE HELICOPTER TOUCHED DOWN ON AN OUTCROPPING OF ROCK & ROCKED BACKWARD. SUBSEQUENTLY, THE TAIL STINGER & TAIL ROTOR BLADES STRUCK THE TERRAIN & THE HELICOPTER WAS DAMAGED. LATER, THE CFI SAID HE BELIEVED THE TAIL ROTOR CONTROL CABLES HAD UNSPOOLED FROM THE DRUM & RESULTED IN THE LOSS OF CONTROL. HOWEVER, A POST-ACDNT EXAM FAILED TO REVEAL EVIDENCE OF A PRE-ACDNT FAILURE OR MALFUNCTION. DENSITY ALT WAS APRX 8600'. APRX 7 MIEAST AT JEFFCO ARPT, THE WIND WAS FROM 140 DEG AT 10 KTS.

## Aircraft

- Registration: [N7411N](https://openairdocs.org/deregistered/N7411N-2018-01-08), registration cancelled 2018-01-08, S/N 2110, built 1961 (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: 2110
- Airframe hours: 5885
- Engines: LYCOMING VO-540-C2A 305 horsepower reciprocating
- Damage: Substantial damage
- Flight: Instructional, Part 91
- Operator: Harry G. Laforge, doing business as Hoffman Pilot Center
- Registered owner: Harry G Laforge
- Airworthiness certificate: Standard, Normal
- Last inspection: 100 hour, October 15, 1988, 51 hours before
- Departed: BJC, BROOMFIELD, CO
- Destination: BJC

## Flight crew

As NTSB recorded them. NTSB leaves out names.

- Pilot; age 42; commercial, flight instructor; airplane ratings: single-engine land; medical: class 2, valid medical--w/ waivers/lim; seat: left; flight hours: 1,897 total, 350 in this make and model, 1,457 as pilot in command, 35 in the last 90 days, 1 in the last 24 hours

## Weather

- Conditions: Visual (VMC), Day
- Wind: 140° at 10 knots
- Visibility: 60 statute miles
- Lowest ceiling: 20,000 ft broken
- Temperature: 73 °F, dew point 28 °F
- Altimeter: 30.00 inHg
- Observed at: BJC, 7 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 19890309003449A](https://openairdocs.org/incident/19890309003449A), Mar 9, 1989: Hiller UH12E, Golden, CO, Substantial damage. Lost tail rotor efectiveness while hovering after a practice pinnacle approach. Set it down, tail rotor hit a rock.

## Other investigations on N7411N (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 DEN85IA117](https://openairdocs.org/ntsb/DEN85IA117), Apr 17, 1985: Hiller UH-12E (N7411N), Broomfield, CO, incident, minor damage
- [NTSB SEA76DYG73](https://openairdocs.org/ntsb/SEA76DYG73), Aug 10, 1976: Hiller Acft UH-12E (N7411N), Kennewick, WA, 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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