ACCORDING TO STATEMENTS FROM THE PILOT AND PASSENGERS, AFTER DEPARTURE THE AIRCRAFT CLIMBED TO ABOUT 2,000 FEET MSL OVER THE WATER AND CRUISED ALONG THE SOUTH COAST OF THE ISLAND WITH THE INTENTION OF CIRCUMNAVIGATING THE ISLAND BEFORE RETURNING TO TORRANCE. THE PILOT REPORTED THAT THE ENGINE BEGAN TO SPUTTER AND THE PASSENGERS SAID THE ENGINE WAS MAKING DIESELING TYPE NOISE. ALL THREE PERSONS SAID THE PROPELLER CONTINUED TO TURN, BUT THE ENGINE SEEMED TO HAVE NO POWER OUTPUT. THE PILOT SAID HE IMMEDIATELY TURNED BACK TOWARD THE AIRPORT, BUT THE AIRCRAFT WAS LOOSING ALTITUDE AND HE THOUGHT THEY WOULD NOT CLEAR THE HILLS BETWEEN THEIR PRESENT POSITION AND THE FIELD. THE PILOT REPORTED THAT HE OBSERVED A RELATIVELY FLAT PLATEAU AND TURNED TOWARD IT WITH THE INTENTION OF LANDING ON A DIRT ROAD. WHILE DESCENDING TOWARD THE ROAD, THE AIRCRAFT COLLIDED WITH A SCRUB OAK TREE SHORT OF THE OPEN AREA. THE AIRCRAFT CAUGHT FIRE AFTER COMING TO REST. THE POST CRASH FIRE TOTALLY CONSUMED THE AIRCRAFT. ALL ENGINE ACCESSORIES INCLUDING THE IGNITION AND FUEL SYSTEMS WERE DESTROYED. NO UNUSUAL INTERNAL ENGINE OPERATING CONDITION WAS NOTED DURING A TEAR DOWN.