NTSB Identification: LAX89FA136.
The docket is stored on NTSB microfiche number 39166.
Accident occurred Sunday, March 26, 1989 in BEAR VALLEY, CA
Probable Cause Approval Date: 07/09/1990
Aircraft: AEROSPATIALE AS-355-F, registration: N84MH
Injuries: 3 Uninjured.

NTSB investigators either traveled in support of this investigation or conducted a significant amount of investigative work without any travel, and used data obtained from various sources to prepare this aircraft accident report.

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.

The National Transportation Safety Board determines the probable cause(s) of this accident to be:

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.

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