Witnesses observed the aircraft a little above the tree tops prior to colliding with a high voltage tension wire. The two passengers (ages 10 & 11) were seated in the right front seat, both using the same seat belt. The surviving passenger stated they had requested the pilot to fly an "up & down flight path" which the pilot had performed on previous occasions to thrill the boys. He also stated that the engine sounded normal during the altitude changes but might have sputtered the last time they were going up. The fuel selector was positioned to the right tank. The right fuel tank was not ruptured. The right wing separated from the fuselage at the wing root and there was no fire damage of the wing root noted although the right wing root was found approximately 8 ft from the fire-ridden cabin area. There was no evidence of fuel spillage in the immediate area of the right wing. The mechanic who loaded the right wing on a truck bed observed approximately 1 pint of fuel spill out of the right wing root. The aircraft's flight path was facing the sun.