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runway about 20-25 feet high, went a few hundred feet down the runway and made a steep climbing turn over the trees to the east of the runway. He estimated the aircraft climbed to an altitude of 75 or 100 feet over the tree tops. These trees are reported to be 100 feet high. The witness further stated that the flight " . . . was holding its own until the propeller oversped again and the aircraft made a descending turn toward the west." He heard the sound of the crash, did not see the impact, but did see the resulting fire. The witness did not know whether the landing gear or landing flaps were extended during the approach to Thun Field or during the go-around. However, he stated that the landing lights were on during the landing approach. A number of other witnesses heard the sounds of the aircraft from various ground positions and one of them saw a flame shoot out of one engine. None of these witnesses saw anything else significant other than an airplane descending toward Thun Field.
The aircraft struck the ground left wing tip first and nose low. The left wing struck two trees 36 feet beyond the point of initial impact, tearing off the wing and causing the aircraft to rotate in a counterclockwise direction until it skidded, tail first, on its belly to a position 219 feet from the point of initial impact. Both engines were torn from the aircraft, the cockpit area was severely damaged, and the fuselage was broken just aft of the main cargo door. The left wing fuel tanks separated from the wing and burned after impact. The captain was thrown from the aircraft still strapped in his seat. He received multiple fractures and burns. The first officer did not recall how he got out of the wreckage, but was found some distance from the aircraft suffering from a broken leg, concussion. and burns.
Examination of the aircraft wreckage showed that all the major aircraft components were in the wreckage area. The landing gear and flaps were found in the "UP" position. The rudder trim tab was found set 2-3/4 inches to the right (nose left} and the right aileron tab was 1-3/4 inches up (right wing up). Both settings are approximately 50 percent of the respective trim tab's travel. The elevator trim tab settings could not be determined. No evidence was found of any pre-accident damage or malfunction of the flight control systems or the aircraft structure.
Examination of the engines showed both to be relatively intact with the propellers attached. The propeller dome of the left propeller was removed and the piston was found positioned at the low pitch (10°) stop. Examination of the carburetor from the left engine showed the mixture in the "full rich" position with the control arm bent away from the carburetor. The throttle use in the full open position, and the throttle control rod that connects the throttle arm to the jack shaft was separated from the rod end at the carburetor control arm. The internal threads of the rod end were worn. The throttle control rod was recovered with the lock nut in place on the carburetor end of the rod. The threads were worn away and the rod could be inserted into the mating rod and fitting without the threads engaging. A metal washer, found between the carburetor adapter and the blower case, had cut a hole in the gasket during installation. The carburetor passed a bench check satisfactorily. All other engine components were found in a normal condition except the propeller governor and the feather pump and motor assembly.
The pressure cutout switch in the propeller governor was found to have five pressure adjusting shims installed. A bench check revealed that the switch operated it 700-745 p.s.i. Three shims were removed and the switch opened at 590 p.s.i. which is a normal setting. The switch, as installed. was opening approximately 100 p.s.i. higher than specified by the overhaul manual. When retested by the overhaul facility with the five shins reinstalled the switch opened at 665-670 p.s.i. The published limits are 575-625 p.s.i. The records of the overhaul facility indicated that
