# NTSB ATL90FA089: Hiller UH-12D, N94496, Soddy-Daisy, TN, March 31, 1990

- Type: NTSB accident investigation
- Classification: Accident · Fatal · Field investigation · Final report
- Date: March 31, 1990, 13:38 local (18:38 UTC)
- Place: Soddy-Daisy, TN
- Coordinates: 35.260704, -85.169425 (estimated)
- Nearby events: https://openairdocs.org/map.md?lat=35.2607&lon=-85.1694&mi=10
- Phase of flight: [Initial climb](https://openairdocs.org/ntsb-phases/350) (OpenAirDocs' grouping)
- Highest injury: Fatal
- Injuries: 1 fatal, 1 serious, 1 minor
- Status: Completed, report November 9, 1992
- Report: Approved by Office Director
- NTSB case key (mKey): 8119
- NTSB case page: https://web.ntsb.gov/investigations/?ntsbnumber=ATL90FA089
- NTSB report (PDF, downloads): https://data.ntsb.gov/carol-repgen/api/Aviation/ReportMain/GenerateNewestReport/8119/pdf
- Page: https://openairdocs.org/ntsb/ATL90FA089

## Probable cause

FATIGUE INDUCED FAILURE OF THE COLLECTIVE PITCH PUSH ROD (ADJUSTABLE) DURING FLIGHT, AND THE FAILURE OF THE PILOT TO PROVIDE ROUTINE MAINTENANCE. THE PILOT'S LACK OF EXPEREINCE AND HIS FAILURE TO OBTAIN REQUIRED TRAINING AND CERTIFICATION WERE FACTORS IN THE ACCIDENT.

## 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
  - rotorcraft flight control,collective control rod - fatigue (cause)
  - rotorcraft flight control,collective control rod - failure,total (cause)
  - maintenance,annual inspection - not performed, pilot in command (cause)
  - inadequate initial training, pilot in command (contributing factor)
  - lack of total experience, pilot in command (contributing factor)
- Forced landing, descent - uncontrolled
- In flight collision with object, descent - uncontrolled
  - object - tree(s)

## Analysis

SHORTLY AFTER TAKEOFF, THE PILOT OBSERVED DECREASING ENGINE AND ROTOR RPM. HE LOWERED THE COLLECTIVE, BUT THE RPM DID NOT RETURN. THE HELICOPTER COLLIDED WITH TREES AND TERRAIN DURING THE FORCED LANDING ATTEMPT. AN INSPECTION OF THE HELICOPTER REVEALED THAT THE COLLECTIVE PITCH PUSH ROD (ADJUSTABLE) HAD FAILED IN FATIGUE. THE LAST RECORDED MAINTENANCE WAS PERFORMED ON FEBRUARY 22, 1988, MORE THAN TWO YEARS PRIOR TO THE ACCIDENT. THE PILOT/OWNER WAS OPERATING THE HELICOPTER WITH A STUDENT PILOT CERTIFICATE AND WAS CARRYING PASSENGERS.

## Aircraft

- Registration: [N94496](https://openairdocs.org/deregistered/N94496-2014-11-24), registration cancelled 2014-11-24, S/N 1341, built 1961 (OpenAirDocs)
- Reported make and model: HILLER UH-12D
- Registry model: [Hiller UH-12D](https://openairdocs.org/model/hiller-uh-12d) (registry code 4360118) (OpenAirDocs)
- Registry engine: [Lycoming VO-540 series](https://openairdocs.org/engine/lycoming-vo-540-series) (registry code 41534, reciprocating) (OpenAirDocs)
- Category: Helicopter
- Serial number: 1341
- Airframe hours: 6125
- Engines: LYCOMING O-435-A1C 250 horsepower reciprocating
- Damage: Substantial damage
- Flight: Personal, Part 91
- Registered owner: Stanfield, Glenda P.
- Airworthiness certificate: Standard, Normal
- Departed: NONE, HIXSON, TN
- Destination: NONE

## Flight crew

As NTSB recorded them. NTSB leaves out names.

- Pilot; age 41; student; medical: class 3, valid medical--no waivers/lim.; seat: center; toxicology performed; flight hours: 46 total, 30 in this make and model

## Weather

- Conditions: Visual (VMC), Day
- Wind: 180° at 5 knots
- Visibility: 12 statute miles
- Lowest ceiling: none
- Temperature: 70 °F, dew point 57 °F
- Altimeter: 29.00 inHg
- Observed at: CHA, 13 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 19900331007339A](https://openairdocs.org/incident/19900331007339A), Mar 31, 1990: Hiller UH12D, Soddy Daisy, TN, Substantial damage, 1 fatal. Collective pitch push rod broke. Unable to control rotor pitch crashed in trees. Unairworthy and poorly maintained.

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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