CHI96LA015

The pilot stated the airplane was in cruise flight at 6,500 feet mean sea level when the airplane's engine 'began to run rough, then lose power.' The pilot 'selected a field for emergency landing and made an approach to the field.' The airplane struck the top of a tree and subsequently impacted the terrain. Field examination of the engine revealed impact damage to the face of the number three cylinder piston. A piece of metal was found imbedded in the piston. The exhaust rocker arm was removed on the number three cylinder revealing the valve stem extended approximately 1/2 inch and the valve head broken off. No other anomalies to the engine were found.

On October 21, 1995, at 1700 central daylight time, a Piper PA- 28-140, N6932W, piloted by a private pilot, sustained substantial damage during a forced landing to a clearing in a wooded area in Ocie, Missouri. Visual meteorological conditions prevailed at the time of the accident. The flight was operated under 14 CFR Part 91. A flight plan was not on file. The pilot and passenger sustained serious injuries. The business flight departed Vichy, Missouri, at 1530 cdt, and was en route to Mena, Arkansas.

In his written statement, the pilot reported that he was cruising at 6,500 feet mean sea level (MSL) when the airplane's engine "began to run rough, then lose power." The pilot "selected a field for emergency landing, made an approach to the field and came up approximately 300 feet short." The airplane struck the top of a tree and subsequently impacted the terrain.

The Federal Aviation Administration (FAA) inspector who examined the wreckage at the site found all of the airplane parts together resting in a clearing approximately 130 feet from the base of a 50 foot high tree which showed evidence of shear impact damage near the top. Leaves and branches from the same tree were found embedded in the leading edges of the left wing and left horizontal stabilizer. An impact ground scar was measured 108 feet from the base the tree. Both wings had separated from the fuselage at the wing roots. The crew compartment showed twisting and bending forward of the cabin door. The crew compartment floor had been crushed and pushed upward. The fuselage aft of the cabin door, the horizontal and vertical stabilizers, elevator and rudder showed minor damage. The engine, had separated from the fuselage at the firewall and was lying on its right side. The propeller was still attached to the engine. One blade was straight and the other blade was bent slightly rearward and twisted. Examination of the flight controls revealed complete continuity.

A field examination of the engine was performed at the accident site on October 23, 1995. Thumb compression was confirmed on all engine cylinders except for the number three cylinder. Resistance to crankshaft rotation was noted each time the piston in the number three cylinder reached top-dead-center (TDC). Further examination of the number three cylinder revealed impact damage to the face of the piston. A piece of metal was found imbedded in the piston. The exhaust rocker arm was removed on the number three cylinder revealing the valve stem extended approximately 1/2 inch. A portion of the valve head was broken off. The throttle and mixture controls on the carburetor were confirmed in place. Oil supply to the engine was also confirmed. No other anomalies to the engine were found.