THE HELICOPTER WAS BEING USED ON A SEISMIC DATA ACQUISTION OPERATION. WHILE LANDING BY A ROAD IN MOUNTAINOUS TERRAIN AT AN ELEVATION OF APRX 8400 FT, THE HELICOPTER WAS OBSERVED TO APPROACH TO A HOVER OVER THE ROADWAY. A CONSIDERABLE AMOUNT OF DUST WAS BLOWN FROM THE ROTOR DOWNWASH CAUSING PERSONNEL ON THE GROUND TO COVER THEIR EYES & LOOK AWAY. THE HELICOPTER WAS NEXT OBSERVED TO PULL UP & AWAY FROM THE GROUND PERSONNEL, THEN MOVE UP THE HILL (BESIDE THE ROAD) & TURN RIGHT TO FACE THE HILLSIDE. GROUND PERSONNEL REPORTED THAT IT THEN MADE AN UNUSUAL NOISE, SPUN AROUND, BEGAN TO WHIP BACK & FORTH, THEN DESCENDED INTO TREES IN AN UNCONTROLLED MANNER. AFTER IMPACT, IT ROLLED DOWN THE HILLSIDE & CAMETO REST AT THE ROAD. THE PLT WAS INJURED & COULD NOT REMEMBER THE OCCURRENCE. GROUND PERSONNEL THOUGHT THE ENG LOST POWER, BUT NO PREIMPACT FAILURE WAS FOUND. SEVERAL CIRCUIT BREAKERS WERE 'OUT' BUT 2 OF THEM (BOOST PUMP) WOULD NORMALLYHAVE BEEN PULLED AFTER LANDING. WIND FROM SOUTH, 10 KTS. WITNESS SAID, GUST BLEW DUST BACK TOWARD ACFT, WHILE HOVERING.

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

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

Contributing Factors

TERRAIN CONDITION..MOUNTAINOUS/HILLY

Contributing Factors

TERRAIN CONDITION..DOWNHILL

Contributing Factors

TERRAIN CONDITION..HIGH OBSTRUCTION(S)

Contributing Factors

WEATHER CONDITION..HIGH DENSITY ALTITUDE

Contributing Factors

WEATHER CONDITION..UNFAVORABLE WIND

Contributing Factors

WEATHER CONDITION..GUSTS

Index for Aug1983 | Index of months