# NTSB SEA85LA053: Hughes 369D, N8306F, Taholah, WA, February 4, 1985

- Type: NTSB accident investigation
- Classification: Accident · Minor injuries · Limited investigation · Final report
- Date: February 4, 1985, 15:00 local (23:00 UTC)
- Place: Taholah, WA
- Coordinates: 47.310901, -124.219291 (estimated)
- Nearby events: https://openairdocs.org/map.md?lat=47.3109&lon=-124.2193&mi=10
- Phase of flight: [Maneuvering](https://openairdocs.org/ntsb-phases/450) (OpenAirDocs' grouping)
- Highest injury: Minor injuries
- Injuries: 1 minor
- Status: Completed
- Report: Approved by Office Director
- NTSB case key (mKey): 40110
- NTSB case page: https://web.ntsb.gov/investigations/?ntsbnumber=SEA85LA053
- NTSB report (PDF, downloads): https://data.ntsb.gov/carol-repgen/api/Aviation/ReportMain/GenerateNewestReport/40110/pdf
- Page: https://openairdocs.org/ntsb/SEA85LA053

## Sequence of events

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

- Airframe/component/system failure/malfunction, hover
  - rotor drive system,main rotor mast(drive shaft) - fatigue (cause)
  - rotor drive system,main rotor mast(drive shaft) - failure,total
- Forced landing, descent - emergency
  - remedial action - not possible, pilot in command
- In flight collision with terrain/water, maneuvering - turn to landing area (emergency)
- Roll over, maneuvering - turn to landing area (emergency)

## Analysis

THE ACFT HAD LIFTED OFF DURING AN EXTERNAL LOAD OPERATION WHEN THE PLT FELT A 'VIBRATION/SHUDDER'. THE RIGHT SKID CONTACTED THE GROUND AND THE HELICOPTER ROLLED OVER DURING AN ATTEMPT TO MANEUVER THE HELICOPTER AWAY FROM GROUND PERSONNEL. INSPECTION REVEALED THE MAIN ROTOR DRIVE SHAFT SEPARATED APRX 3 INCHES FROM THE SPLINED END OF THE SHAFT. METALLURGICAL EXAMINATION DISCLOSED THE SHAFT FAILED FROM UNIDIRECTIONAL FATIGUE INITIATING FROM SURFACE PITS ON THE SHAFT.

## Aircraft

- Registration: [N8306F](https://openairdocs.org/aircraft/N8306F), registered now, S/N 380274D, built 1978 (OpenAirDocs)
- Reported make and model: HUGHES 369D
- Registry model: [Hughes Helicopters HUGHES 369D](https://openairdocs.org/model/hughes-helicopters-hughes-369d) (registry code 4470706) (OpenAirDocs)
- Registry engine: [Allison 250 SER 400HP](https://openairdocs.org/engine/allison-250-ser-400hp) (registry code 03013, turbo-shaft) (OpenAirDocs)
- Category: Helicopter
- Serial number: 380247D
- Airframe hours: 17396
- Engines: ALLISON 250-C20B 375 horsepower turbo shaft
- Damage: Destroyed
- Flight: Other work use, Part 133
- Registered owner: Olympic Air, Inc.
- Airworthiness certificate: Standard, Normal
- Last inspection: Annual, December 24, 1984, 108 hours before

## Flight crew

As NTSB recorded them. NTSB leaves out names.

- Pilot; age 32; commercial; airplane ratings: single-engine land; instrument ratings: airplane; medical: class 2, valid medical--no waivers/lim.; seat: left; flight hours: 3,876 as pilot in command, 222 in the last 90 days

## Weather

- Conditions: Visual (VMC), Day
- Wind: 290° at 2 knots
- Visibility: 10 statute miles
- Lowest ceiling: 20,000 ft overcast
- Temperature: 36 °F, dew point 19 °F
- Altimeter: 30.00 inHg
- Observed at: HQM, 27 nm away

## Other investigations on N8306F (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 SEA99LA082](https://openairdocs.org/ntsb/SEA99LA082), Jun 8, 1999: Hughes 369D (N8306F), Southbend, WA, substantial damage. Probable cause: The complete loss of power, due to a failure of the compressor impeller disk. Factors include the low altitude of the helicopter at the time of the power loss, and the need to autorotate in a…
- [NTSB SEA97LA118](https://openairdocs.org/ntsb/SEA97LA118), May 21, 1997: Hughes 369D (N8306F), Moclips, WA, substantial damage. Probable cause: Inadequate installation of the fuel control by company maintenance personnel and a loose nut on a line. A disconnected Pc line was a factor.
- [NTSB SEA90LA081](https://openairdocs.org/ntsb/SEA90LA081), May 21, 1990: Hughes 369D (N8306F), Kelso, WA, no damage, 1 fatal. Probable cause: FAILURE OF THE PILOT TO KEEP THE EXTERNAL LOAD CLEAR OF OBSTACLES (TREES). FACTORS RELATED TO THE ACCIDENT WERE: FAILURE OF THE PILOT AND GROUND CREWMAN TO FOLLOW SAFETY PROCEDURES, AND THE PROXIMITY…
- [NTSB DEN79FTE19](https://openairdocs.org/ntsb/DEN79FTE19), Jan 21, 1979: Hughes 500D (N8306F), Marble, 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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