THE ACFT WAS ON A FLT TO A RADIO TRANSMITTER SITE AT ABOUT THE 7000 FT LEVEL IN MOUNTAINOUS TERRAIN. DURING ARRIVAL TO THE HELIPAD, THE PLT NOTICED THAT SEVERAL VEHICLES WERE PARKED ON THE LANDING SURFACE. WHILE IN A HOVER, HE MANEUVERED THE HELICOPTER TO AN ADJACENT ROAD & BEGAN INSPECTING IT FOR SUITABILITY AS A LANDING AREA. HE DECIDED THAT THE ROAD WAS UNSATISFACTORY & APPLIED POWER & COLLECTIVE TO BEGIN A LEFT CLIMBING TURN. ACCORDING TO ALL STATEMENTS, THE ENG'S RESPONSE TO THE POWER DEMAND WAS A GRADUAL POWER FADE UNTIL IT QUIT. SUBSEQUENTLY, THE ACFT LANDED HARD IN A BUSH COVERED AREA & WAS DAMAGED. THE ENG WAS EXAMED & OPERATIONALLY TESTED, BUT NO ABNORMALITIES WERE NOTED. THE DENSITY ALTITUDE WAS CALCULATED TO BE ABOUT 7800 TO 8650 FT. ACCORDING TO THE FLT MANUAL, AT THE ESTIMATED WEIGHT, THE HELICOPTER'S HOVERING CEILING WAS 13,000 FT IN GROUND EFFECT & 8300 FT OUT OF GROUND EFFECT.