# NTSB ANC90LA147: Aerospatiale AS-350-B, N26492, Juneau, AK, August 17, 1990

- Type: NTSB accident investigation
- Classification: Accident · No injuries · Limited investigation · Final report
- Date: August 17, 1990, 09:15 local (17:15 UTC)
- Place: Juneau, AK
- Location: 58.3019° N, 134.4197° W: Placed by OpenAirDocs: center of Juneau, AK, within about 29 miles (OpenAirDocs)
- Nearby events: https://openairdocs.org/map.md?lat=58.3019&lon=-134.4197&mi=10
- Phase of flight: [Initial climb](https://openairdocs.org/ntsb-phases/350) (OpenAirDocs' grouping)
- Highest injury: No injuries
- Injuries: 6 uninjured
- Status: Completed, report December 30, 1992
- Report: Approved by Office Director
- NTSB office: Alaska Regional Office
- NTSB case key (mKey): 5430
- NTSB case page: https://web.ntsb.gov/investigations/?ntsbnumber=ANC90LA147
- NTSB report (PDF, downloads): https://data.ntsb.gov/carol-repgen/api/Aviation/ReportMain/GenerateNewestReport/5430/pdf
- Page: https://openairdocs.org/ntsb/ANC90LA147

## Probable cause

FAILURE OF THE FREE TURBINE INTERMEDIATE PINION DRIVEN GEAR AND SUBSEQUENT DISINTEGRATION OF THE FREE TURBINE ASSEMBLY.

## Sequence of events

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

- Loss of engine power(total) - mech failure/malf, takeoff - initial climb
  - turboshaft engine,free(power) turbine - failure,total (cause)
- Forced landing, descent - emergency
  - autorotation - performed, pilot in command
- In flight collision with terrain/water, landing - flare/touchdown

## Analysis

SHORTLY ATER TAKEOFF, THE HELICOPTER EXPERIENCED A COMPLETE ENGINE FAILURE. THE PILOT MADE AN EMERGENCY LANDING ONTO AN OPEN LOT. THE ENGINE FAILURE WAS DUE TO A FAILURE AND SEPARATION OF THE TURBINE INTERMEDIATE PINION DRIVEN GEAR WEB UNIT.

## Aircraft

- Registration: N26492 (not matched to a registry record)
- Reported make and model: AEROSPATIALE AS-350-B
- Category: Helicopter
- Serial number: 1066
- Airframe hours: 4078
- Engines: Turbomeca ARRIEL 1B 650 horsepower turbo shaft
- Damage: Substantial damage
- Flight: Part 135
- Registered owner: Temsco Helicopter
- Airworthiness certificate: Standard, Normal
- Last inspection: Continuous airworthiness, August 16, 1990, 5 hours before
- Flight plan: Company VFR

## Flight crew

As NTSB recorded them. NTSB leaves out names.

- Pilot; age 25; commercial, flight instructor; medical: class 2, valid medical--no waivers/lim.; seat: front; flight hours: 910 total, 291 in this make and model, 856 as pilot in command, 297 in the last 90 days, 117 in the last 30 days, 5 in the last 24 hours

## Weather

- Conditions: Visual (VMC), Day
- Wind: calm
- Visibility: 20 statute miles
- Lowest ceiling: 4,000 ft broken
- Temperature: 59 °F, dew point 54 °F
- Altimeter: 29.00 inHg

## 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 19900817033939A](https://openairdocs.org/incident/19900817033939A), Aug 17, 1990: Snias AS350B, Juneau, AK, Substantial damage. Engine overspeed. Auto rotated to small lot. Hit tail rotor. Pinion drive gear from gear nfb to MO5 unit failed.

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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