# NTSB CHI83LA297: Hiller UH-12E, N4028K, Brooten, MN, July 5, 1983

- Type: NTSB accident investigation
- Classification: Accident · No injuries · Limited investigation · Final report
- Date: July 5, 1983, 08:00 local (13:00 UTC)
- Place: Brooten, MN
- Location: 45.5001° N, 95.1157° W: Placed by OpenAirDocs: center of Brooten, MN, within about 6 miles (OpenAirDocs)
- Nearby events: https://openairdocs.org/map.md?lat=45.5001&lon=-95.1157&mi=10
- Phase of flight: [Initial climb](https://openairdocs.org/ntsb-phases/350) (OpenAirDocs' grouping)
- Highest injury: No injuries
- Injuries: 1 uninjured
- Status: Completed
- Report: Approved by Office Director
- NTSB case key (mKey): 12248
- NTSB case page: https://web.ntsb.gov/investigations/?ntsbnumber=CHI83LA297
- NTSB report (PDF, downloads): https://data.ntsb.gov/carol-repgen/api/Aviation/ReportMain/GenerateNewestReport/12248/pdf
- Page: https://openairdocs.org/ntsb/CHI83LA297

## Sequence of events

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

- Airframe/component/system failure/malfunction, takeoff - initial climb
  - rotor drive system,tail rotor gearbox(90 deg) - disconnected (cause)
  - maintenance,installation - improper, other maintenance personnel (cause)
- Loss of control - in flight, takeoff - initial climb
  - directional control - not possible, pilot in command (contributing factor)
- Forced landing, landing - flare/touchdown
  - autorotation - performed, pilot in command (contributing factor)
- In flight collision with object, landing - flare/touchdown
  - object - vehicle (contributing factor)

## Analysis

THE HELICOPTER HAD JUST LIFTED OFF OF THE FLATBED OF A TRUCK WHEN IT STARTED TO SPIN. THE PLT LOWERED THE COLLECTIVE, REDUCED THE POWER & LANDED BESIDE THE TRUCK. DURING TOUCHDOWN, THE MAIN ROTOR BLADES STRUCK THE TRUCK. AN INVESTIGATION REVEALED THAT THE THRUST BEARING, PN 25200-3, IN THE TAIL ROTOR DRIVE WAS INSTALLED BACKWARDS. THIS ALLOWED THE BEVELED DRIVE GEAR TO MOVE FORWARD & BECOME DISENGAGED FROM THE TAIL ROTOR DRIVE GEAR.

## Aircraft

- Registration: [N4028K](https://openairdocs.org/deregistered/N4028K-2018-01-18), registration cancelled 2018-01-18, S/N 5069 (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: 5069
- Airframe hours: 545
- Engines: ALLISON 250-C20B 305 horsepower turbo shaft
- Damage: Substantial damage
- Flight: Aerial application, Part 137
- Registered owner: Bonanza Valley Aviation
- Airworthiness certificate: Special, Restricted (Special)
- Last inspection: Annual, April 15, 1983, 117 hours before
- Departed: BROOTEN, MN

## Flight crew

As NTSB recorded them. NTSB leaves out names.

- Pilot; age 44; commercial; airplane ratings: single-engine land; medical: class 2, valid medical--no waivers/lim.; seat: center; flight hours: 3,260 total, 360 in this make and model, 3,200 as pilot in command, 120 in the last 90 days, 4 in the last 24 hours

## Weather

- Conditions: Visual (VMC), Day
- Wind: 360° at 4 knots
- Visibility: 25 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 19830705028519A](https://openairdocs.org/incident/19830705028519A), Jul 5, 1983: Hiller UH12E, Brooten, MN, Substantial damage. Helicopter began to yaw on leaving flatbed truck. Aborted. Rotor hit truck. Tail rotor drive bearing on backwards.

## Other investigations on N4028K (1)

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 FTW80FQA40](https://openairdocs.org/ntsb/FTW80FQA40), Aug 15, 1980: Hiller Acft UH-12E (N4028K), Burnham, NM, 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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