# NTSB LAX90LA050: Hughes 369HS, N9161F, Waimea, HI, December 9, 1989

- Type: NTSB accident investigation
- Classification: Accident · No injuries · Limited investigation · Final report
- Date: December 8, 1989, 15:30 local (Dec 9, 1989, 01:30 UTC)
- Place: Waimea, HI
- Coordinates: 21.949567, -159.670883 (estimated)
- Nearby events: https://openairdocs.org/map.md?lat=21.9496&lon=-159.6709&mi=10
- Phase of flight: [Enroute](https://openairdocs.org/ntsb-phases/400) (OpenAirDocs' grouping)
- Highest injury: No injuries
- Injuries: 5 uninjured
- Status: Completed, report September 9, 1992
- Report: Approved by Office Director
- NTSB case key (mKey): 26703
- NTSB case page: https://web.ntsb.gov/investigations/?ntsbnumber=LAX90LA050
- NTSB report (PDF, downloads): https://data.ntsb.gov/carol-repgen/api/Aviation/ReportMain/GenerateNewestReport/26703/pdf
- Page: https://openairdocs.org/ntsb/LAX90LA050

## Probable cause

THE IMPROPER INSTALLATION OF THE PC TUBE BY COMPANY MAINTENANCE PERSONNEL, WHICH RESULTED IN FATIGUE FAILURE OF THE TUBE DUE TO INDUCED BENDING STRESSES.

## Sequence of events

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

- Loss of engine power(partial) - mech failure/malf, cruise
  - maintenance,installation - improper, company maintenance personnel (cause)
  - bleed air system,lines - incorrect (cause)
  - bleed air system,lines - bent (cause)
  - bleed air system,lines - fatigue (cause)
- Forced landing, descent - emergency
- Roll over, landing - flare/touchdown
  - terrain condition - rough/uneven
  - terrain condition - water

## Analysis

THE CERTIFICATED AIR LINE TRANSPORT PILOT WAS CONDUCTING A HELICOPTER SIGHTSEEING FLIGHT WITH 4 PASSENGERS WHEN THE ENGINE SUDDENLY LOST POWER. THE PILOT MADE AN EMERGENCY AUTOROTATION TO THE BOTTOM OF A SMALL RIVER BOTTOM. WHILE LANDING, THE HELICOPTER ROLLED OVER. EXAMINATION OF THE ENGINE SHOWED THAT THE FUEL CONTROL PC TUBE TO THE POWER TURBINE GOVERNOR HAD FRACTURED, CAUSING THE ENGINE TO GO TO A FLIGHT IDLE CONDITION. THIS TUBE WAS FOUND TO EXCEED THE SPECIFIED REQUIRED LENGTH OF MANUFACTURE. DURING INSTALLATION, THE TUBE WAS BENT BY COMPANY MAINTENANCE PERSONNEL TO FIT. METALLURGICAL EXAM DISCLOSED A FRACTURE DUE TO FATIGUE NEAR THE FUEL CONTROL END. THIS FATIGUE WAS INTRODUCED BY BENDING STRESSES IN THE TUBE.

## Aircraft

- Registration: N9161F (not matched to a registry record)
- Reported make and model: HUGHES 369HS
- Category: Helicopter
- Serial number: 8305115
- Airframe hours: 12198
- Engines: ALLISON 250-C20 375 horsepower turbo shaft
- Damage: Substantial damage
- Flight: Part 91
- Operator: Air Kaui, Inc.
- Registered owner: Heli-Dyne Inc.
- Airworthiness certificate: Standard, Normal
- Last inspection: 100 hour, November 19, 1989, 85 hours before
- Departed: LIH, LIHUE, HI
- Flight plan: Company VFR

## Flight crew

As NTSB recorded them. NTSB leaves out names.

- Pilot; age 39; airline transport, flight instructor; airplane ratings: single-engine land, multi-engine land; instrument ratings: airplane, helicopter; medical: class 2, valid medical--no waivers/lim.; flight hours: 11,000 total, 500 in this make and model, 10,000 as pilot in command, 200 in the last 90 days, 75 in the last 30 days, 6 in the last 24 hours

## Weather

- Conditions: Visual (VMC), Day
- Wind: calm
- Visibility: 15 statute miles
- Lowest ceiling: none
- Temperature: 75 °F, dew point -0 °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 19891208049579A](https://openairdocs.org/incident/19891208049579A), Dec 8, 1989: Hughes 369HS, Waimea, HI, Substantial damage. Lost power. Struck rock and rolled on forced landing. Pc air tube and fuel tube assembly lines had cracked.

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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