STINSON 108-2

Full Narrative

The pilot reported that he flew the airplane earlier on the same day as the accident on a 75 mile flight. The pilot stated that before the return flight, he performed a preflight inspection of the airplane including taking fuel samples to check for water or contaminants. None were found. The pilot further stated that he performed engine pre-takeoff checks including magneto and carburetor heat checks prior to departure. The airplane took off and climbed to 3,000 feet. After about 5 minutes the engine began running rough and he switched fuel tanks and applied carburetor heat. No improvement in engine operation was noted. The pilot then turned the airplane toward terrain more suitable for landing. The engine stopped making power and the pilot executed a forced landing. During the landing, the pilot applied brakes with the yoke fully aft and the airplane's tail would raise. The pilot released the brakes to allow the tail to lower. The pilot repeatedly applied and released the brakes attempting to stop the airplane, but the airplane nosed over and came to rest on its top. Examination of the engine after the accident revealed that the aluminum intake tubing had split outward and was fully compromised. The engine was examined and spark was produced on all magneto leads and valve action was verified on all cylinders. One cylinder produced little compression when the engine was rotated. All other cylinders produced compression and suction when the engine was rotated. The cylinder with low compression was removed and examined but no defects were found.