# NTSB ANC91LA085: Bell 206BIII, N302MH, Sheep Mountain, AK, July 1, 1991

- Type: NTSB accident investigation
- Classification: Accident · No injuries · Limited investigation · Final report
- Date: July 1, 1991, 13:30 local (21:30 UTC)
- Place: Sheep Mountain, AK
- Coordinates: 62.099124, -145.530075 (estimated)
- Nearby events: https://openairdocs.org/map.md?lat=62.0991&lon=-145.5301&mi=10
- Phase of flight: [Landing](https://openairdocs.org/ntsb-phases/550) (OpenAirDocs' grouping)
- Highest injury: No injuries
- Injuries: 3 uninjured
- Status: Completed, report March 24, 1993
- Report: Approved by Office Director
- NTSB office: Alaska Regional Office
- NTSB case key (mKey): 5569
- NTSB case page: https://web.ntsb.gov/investigations/?ntsbnumber=ANC91LA085
- NTSB report (PDF, downloads): https://data.ntsb.gov/carol-repgen/api/Aviation/ReportMain/GenerateNewestReport/5569/pdf
- Page: https://openairdocs.org/ntsb/ANC91LA085

## Probable cause

THE PILOT'S LACK OF COMPENSATION FOR WIND CONDITIONS AND CONTINUED OPERATION WITH THE WIND IN THE 'CRITICAL WIND AZIMUTH' AREA WHICH LED TO LIMITED TAIL ROTOR AUTHORITY. CONTRIBUTING TO THE ACCIDENT WAS THE VARIABLE AND GUSTY WIND CONDITIONS.

## Sequence of events

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

- Loss of control - in flight, landing - flare/touchdown
  - weather condition - unfavorable wind (contributing factor)
  - compensation for wind conditions - disregarded, pilot in command (cause)
  - aircraft performance,yawing maneuvers - deteriorated (cause)
  - procedures/directives - not followed, pilot in command (cause)
- Hard landing, landing - flare/touchdown

## Analysis

THE PILOT ATTEMPTED TO LAND ON THE 6,000 FOOT RIDGE AND MADE A GO AROUND. HE MADE A SECOND ATTEMPT WITH THE WIND AS A RIGHT QUARTERING HEADWIND.  THE PILOT STATED THE WIND WAS VARIABLE AND GUSTY.  DURING HIS SECOND APPROACH AND APPROXIMATELY 8 TO 10 FEET ABOVE THE LANDING AREA, HE LOST TAIL ROTOR AUTHORITY AND ELECTED TO LAND IMMEDIATELY UPON THE ONLY AVAILABLE LANDING SURFACE. THE TERRAIN SLOPED AWAY AT A CONSIDERABLE ANGLE AND HE WAS AFRAID OF ROLLING THE HELICOPTER. AN OPERATION SAFETY NOTICE ISSUED BY BELL HELICOPTER OUTLINING THE CONDITIONS FOR LOSS OF TAIL ROTOR AUTHORITY WAS AVAILABLE TO THE PILOT IN THE COMPANY READING FILE. THE READING FILE IS REQUIRED TO BE READ AND INITIALED BY ALL COMPANY PILOTS.

## Aircraft

- Registration: N302MH (not matched to a registry record)
- Reported make and model: BELL 206BIII
- Category: Helicopter
- Serial number: 2958
- Airframe hours: 6142
- Engines: ALLISON 250-C20B 420 horsepower turbo shaft
- Damage: Substantial damage
- Flight: Part 135
- Operator: Maritime Helicopters
- Registered owner: Maritime Helicopters
- Airworthiness certificate: Standard, Normal
- Last inspection: 100 hour, June 29, 1991, 4 hours before
- Flight plan: VFR

## Flight crew

As NTSB recorded them. NTSB leaves out names.

- Pilot; age 54; flight instructor, commercial; medical: class 2, valid medical--w/ waivers/lim; seat: right; flight hours: 9,097 total, 5,000 in this make and model, 8,809 as pilot in command, 162 in the last 90 days, 79 in the last 30 days, 4 in the last 24 hours

## Weather

- Conditions: Visual (VMC), Day
- Wind: variable at 5 knots, gusting 10
- Visibility: 20 statute miles
- Lowest ceiling: none
- Temperature: 54 °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 19910701025289A](https://openairdocs.org/incident/19910701025289A), Jul 1, 1991: Bell 206B, Sheep Mountain, AK, Substantial damage. Lost tail rotor effectiveness landing on a Mountain ridge. Hard landing made to stop rotation.

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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