Accident Overview
During a climb, the engine began to shake violently and lost power. The pilot executed a forced landing to a two-lane highway. During the landing, the airplane impacted an overpass support.
Examination of the Engine
Inspection of the wreckage revealed that the number 2 cylinder had separated from the engine. Further examination of the engine showed sealant applied to the upper portion of the crankcase. The top crankcase fasteners were tested for torque; they began to turn before reaching the specified 96-inch pounds recommended by the manufacturer. When the crankcase was split open, fretting to the parting surfaces was observed. The center main bearing exhibited signs of movement and fretting on the bearing saddle. Fretting was also found on the number 2 and number 3 cylinder flanges and the corresponding crankcase decks.
Maintenance History
The engine was last overhauled on July 14, 1994, and had accumulated a total time of 1285 hours since the overhaul. The top parting surface of the crankcase was resealed on three occasions: February 7, 1997; November 20, 1998; and March 17, 1999. The last noted entry for tightening the crankcase bolts was on June 19, 1998. The number 2 and number 3 cylinders were last removed and replaced on April 2, 1997, by an overhaul facility.