# NTSB LAX89FA136: Aerospatiale AS-355-F, N84MH, Bear Valley, CA, March 26, 1989

- Type: NTSB accident investigation
- Classification: Accident · No injuries · Field investigation · Final report
- Date: March 26, 1989, 12:33 local (20:33 UTC)
- Place: Bear Valley, CA
- Coordinates: 37.959297, -120.870574 (estimated)
- Nearby events: https://openairdocs.org/map.md?lat=37.9593&lon=-120.8706&mi=10
- Phase of flight: [Approach](https://openairdocs.org/ntsb-phases/500) (OpenAirDocs' grouping)
- Highest injury: No injuries
- Injuries: 3 uninjured
- Status: Completed, report July 9, 1990
- Report: Approved by Office Director
- NTSB case key (mKey): 26218
- NTSB case page: https://web.ntsb.gov/investigations/?ntsbnumber=LAX89FA136
- NTSB report (PDF, downloads): https://data.ntsb.gov/carol-repgen/api/Aviation/ReportMain/GenerateNewestReport/26218/pdf
- Page: https://openairdocs.org/ntsb/LAX89FA136

## Probable cause

IMPROPER IN-FLIGHT PLANNING/DECISION BY THE PILOT, WHICH RESULTED IN A LOSS OF AIRCRAFT CONTROL DURING A SLOW SPEED, DOWNWIND APPROACH TO A HIGH ALTITUDE STOLPORT.  CONTRIBUTING FACTORS WERE:  HIGH DENSITY ALTITUDE, TAILWIND, IMPROPER WEATHER EVALUATION BY THE PILOT, SNOW COVERED TERRAIN, WHITEOUT CONDITIONS BEFORE TOUCHDOWN, AND THE SNOWBANK.

## Sequence of events

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

- Loss of control - in flight, approach - vfr pattern - final approach
  - in-flight planning/decision - improper, pilot in command (cause)
  - weather condition - high density altitude (contributing factor)
  - weather condition - tailwind (contributing factor)
  - wrong runway - selected, pilot in command
  - weather evaluation - improper, pilot in command (contributing factor)
  - aborted landing - attempted
  - go-around - not possible
  - autorotation - initiated
  - terrain condition - snow covered (contributing factor)
  - weather condition - whiteout (contributing factor)
  - aircraft control - inadequate
- Roll over, landing
  - terrain condition - snowbank (contributing factor)

## Analysis

THE EMERG MED SVC (EMS/MEDIVAC) FLT DEPARTED MODESTO HOSPITAL TO TRANSPORT A PATIENT FROM BEAR VALLEY, CA. THE PILOT MADE AN APCH TO THE BEAR VALLEY STOLPORT FROM THE SOUTH-SOUTHWEST. ELEV OF THE STOLPORT WAS 7073'. DRG THE APCH AT SLOW SPEED, THE HELICOPTER BEGAN TO YAW TO THE LEFT. THE PLT APPLIED RGT PEDAL, BUT TO NO AVAIL. HE LOWERED THE NOSE TO BEGIN A GO-AROUND, BUT THE YAW BEGAN TO ACCELERATE. THE PLT THEN SHUT DOWN BOTH ENGS & MADE AN AUTOROTATION. JUST BEFORELANDING, LOOSE SNOW WAS BLOWN UP & WHITEOUT CONDITIONS OCCURRED. DRG TOUCHDOWN, THE HELICOPTER PITCHED FORWARD INTO A SNOWBANK & WAS DAMAGED. THE PLT RPRTD THE WIND WAS LIGHT & VARIABLE. A SHERIFF'S DEPUTY RPRTD THE WIND WAS FROM THE SOUTH/SOUTHWEST AT 5 TO 10 KTS. THE INVESTGATION REVEALED NO EVIDENCE OF A TAIL ROTOR DRIVE MALFUNCTION OR FAILURE.

## Aircraft

- Registration: [N84MH](https://openairdocs.org/deregistered/N84MH-2005-11-04), registration cancelled 2005-11-04, S/N 5173, built 1982 (OpenAirDocs)
- Reported make and model: AEROSPATIALE AS-355-F
- Registry model: [Aerospatiale AS 355 F ECUREUIL](https://openairdocs.org/model/aerospatiale-as-355-f-ecureuil) (registry code 8680806) (OpenAirDocs)
- Registry engine: [Allison 250-C20 series](https://openairdocs.org/engine/allison-250-c20-series) (registry code 03020, turbo-prop) (OpenAirDocs)
- Category: Helicopter
- Serial number: 5173
- Airframe hours: 2385
- Engines: ALLISON 250-C20F 250 horsepower turbo shaft
- Damage: Substantial damage
- Flight: Positioning, Part 91
- Operator: Care, Inc, doing business as Mediflight
- Registered owner: Memorial Hospitals Ass.
- Airworthiness certificate: Standard, Normal
- Last inspection: Continuous airworthiness, February 22, 1989, 37 hours before
- Departed: MODESTO, CA
- Flight plan: Company VFR
- Airport: 0Q0, Bear Valley Stolport

## Flight crew

As NTSB recorded them. NTSB leaves out names.

- Pilot; age 40; commercial, flight engineer, airline transport, flight instructor; airplane ratings: multi-engine land, single-engine land; instrument ratings: airplane, helicopter; medical: class 2, valid medical--no waivers/lim.; seat: right; flight hours: 4,700 total, 120 in this make and model, 60 in the last 90 days, 20 in the last 30 days, 1 in the last 24 hours

## Weather

- Conditions: Visual (VMC), Day
- Visibility: 15 statute miles
- Lowest ceiling: none
- Temperature: 36 °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 19890326004639A](https://openairdocs.org/incident/19890326004639A), Mar 26, 1989: Aerosp AS355F1, Bear Valley, CA, Substantial damage. Lost tail rotor authority descending at slow speed for landing. Tried go around. Snow caused whiteout.

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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