# NTSB DEN89DTM02: Hiller UH-12E, N5594N, Mack, CO, May 13, 1989

- Type: NTSB accident investigation
- Classification: Accident · Serious injuries · Final report
- Date: May 13, 1989, 07:48 local (13:48 UTC)
- Place: Mack, CO
- Coordinates: 39.219779, -108.870918 (estimated)
- Nearby events: https://openairdocs.org/map.md?lat=39.2198&lon=-108.8709&mi=10
- Phase of flight: [Maneuvering](https://openairdocs.org/ntsb-phases/450) (OpenAirDocs' grouping)
- Highest injury: Serious injuries
- Injuries: 1 serious
- Status: Completed, report May 22, 1990
- Report: Approved by Office Director
- NTSB case key (mKey): 17560
- NTSB case page: https://web.ntsb.gov/investigations/?ntsbnumber=DEN89DTM02
- NTSB report (PDF, downloads): https://data.ntsb.gov/carol-repgen/api/Aviation/ReportMain/GenerateNewestReport/17560/pdf
- Page: https://openairdocs.org/ntsb/DEN89DTM02

## Probable cause

THE PILOT'S FAILURE TO MAINTAIN PROPER ALTITUDE DURING A SWATH RUN.

## Analysis

THE PILOT STATED THAT DURING A SWATH RUN HE LET THE HELICOPTER GET TOO LOW AND THE SKIDS CONTACTED THE ALFALFA CROP FOLLOWED BY THE SPRAY APPARATUS. THE PILOT WAS UNABLE TO GAIN ALTITUDE AND THE HELICOPTER CONTINUED TO DESCEND INTO THE GROUND AND ROLLED OVER. AN EYE-WITNESSES CONCURRED WITH THE PILOT'S STATEMENT BUT DECLINED TO GIVE A WRITTEN STATEMENT.

## Sequence of events

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

- In flight collision with terrain/water, maneuvering - aerial application
  - terrain condition - crop
  - proper altitude - not maintained, pilot in command (cause)
- Nose over, maneuvering - aerial application

## Aircraft

- Registration: [N5594N](https://openairdocs.org/deregistered/N5594N-1989-07-27), registration cancelled 1989-07-27, S/N 1453 (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: 1453
- Airframe hours: 4313
- Engines: LYCOMING VO-540-C2A 305 horsepower reciprocating
- Damage: Substantial damage
- Flight: Aerial application, Part 137
- Registered owner: Garlitz And Serve, Inc.
- Airworthiness certificate: Special, Restricted (Special)
- Last inspection: Annual, January 22, 1989, 6 hours before
- Departed: MACK, CO

## Flight crew

As NTSB recorded them. NTSB leaves out names.

- Pilot; age 48; commercial; airplane ratings: single-engine land; medical: class 2, valid medical--no waivers/lim.; seat: center; flight hours: 298 total, 8 in the last 90 days, 4 in the last 30 days, 2 in the last 24 hours

## Weather

- Conditions: Visual (VMC), Day
- Wind: 310° at 3 knots
- Visibility: 9 statute miles
- Lowest ceiling: 9,000 ft broken
- Temperature: 48 °F, dew point 36 °F
- Altimeter: 29.00 inHg
- Observed at: GJT, 20 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 19890513011389A](https://openairdocs.org/incident/19890513011389A), May 13, 1989: Hiller UH12E, Mack, CO, Substantial damage. Skids caught in alfalfa while spraying. Helicopter tumbled and crashed.

## Other investigations on N5594N (3)

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 CHI82DA301](https://openairdocs.org/ntsb/CHI82DA301), Aug 10, 1982: Hiller 12E (N5594N), Palisade, MN, substantial damage
- [NTSB CHI81FER59](https://openairdocs.org/ntsb/CHI81FER59), Jul 20, 1981: Hiller Acft UH-12E (N5594N), Glyndon, MN, substantial damage
- [NTSB DEN81FTG01](https://openairdocs.org/ntsb/DEN81FTG01), Oct 3, 1980: Hiller UH12E (N5594N), Argusville, ND, 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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