THE ACFT COLLIDED WITH TREES AT AN ELEVATION OF 8560 FT MSL. THE CRASH SITE WAS ON THE EAST SIDE OF A RIDGE & APRX 30 TO 40 FT BELOW THE RIDGELINE. THE RIDGE RAN NORTHEAST-SOUTHWEST & FORMED THE WEST SIDE OF DRY CANYON. THE PLT STATED THAT THE ENG LOST POWER AT APRX 9000 FT AS THE ACFT WAS APPROACHING THE RIDGELINE. HE STATED THAT HE COULD SEE THE ACFT WOULD NOT CLEAR THE RIDGE. HE TURNED TOWARD THE VALLEY, BUT THE ACFT HIT TREES. HOWEVER, A WITNESS REPORTED THEACFT ENTERED DRY CANYON WHILE AT APRX 400 FT AGL. THE TERRAIN ELEVATION AT THE ENTRANCE WAS ABOUT 6500 FT MSL & THE ENTRANCE IS APRX 3 MI FROM THE CRASH SITE. THE WITNESS STATED THAT A FEW MINUTES AFTER THE ACFT PASSED HIS POSITION, HE HEARD THE ENG ROAR, THEN NOTHING. DURING AN INTERVIEW WITH THE PLT & PASSENGERS, THE INVESTIGATOR ESTABLISHED THAT THE ACFT ENTERED THE CANYON AT APRX 500 FT AGL. THE ENG WAS EXAMINED & A TEST RUN WAS CONDUCTED WHICH SHOWED EVIDENCE OF NORMAL OPERATION.