On January 18, 1997, about 1145 eastern standard time, a Piper PA-28R-200, N57010, was substantially damaged when it collided with a utility pole during a forced landing, near Thorndale, Pennsylvania. The certificated airline transport pilot and private pilot were not injured. Visual meteorological conditions prevailed for the local flight that departed the Chester County G.O. Carlson Airport, Coatesville, Pennsylvania. No flight plan was filed for the instructional flight conducted under 14 CFR Part 91. In a written statement submitted by the airline transport pilot, a certificated flight instructor, he stated the following: "This started as a high performance checkout. After some stalls and slow flight and VOR tracking, engine started to run rough. Switched [fuel] tanks, alternate air and check and switched magnetos. Pointed airplane toward [Coatesville] upon which the engine seized. . . ." On February 25, 1997, the engine was examined at the manufacturer, Textron Lycoming, Williamsport, Pennsylvania under the supervision of the NTSB investigator. The engine model was an IO-360-C1C. During the examination, the engine was unable to be rotated by hand. The engine was then disassembled for further examination. During the disassembly, it was revealed that the crankshaft was separated in two just aft of the number 2 cylinder connecting rod. Another crack was observed just forward of the number 1 cylinder connecting rod. On April 18, 1997, the crankshaft was examined at the NTSB office of research and engineering material laboratory division, Washington, District of Columbia. The following are excerpts from the metallurgist's factual report: "This crankshaft separated through the number 3 crank cheek intersecting the forward radius of the number 3 main journal and the aft radius of the number 2 rod journal. . . .Stereo microscope examination of [the aft] fracture revealed ratchet marks indicative of multiple fracture origins that emanated from the surface of the forward radius of the number 3 main journal. . . .Clam shell marks typical of a fatigue crack progressed away from the ratchet marks. . . .This fatigue crack propagated at least 75% of the crank cheek wall. The area outside the fatigue region contained features typical of overstress separation as well as isolated areas with mechanical damage." "In December 11, 1996, the crankshaft was overhauled by Engine Components, Inc. (ECI), San Antonio, Texas. According to the travel card for this overhaul, an initial magnetic particle inspection method found heat cracking [in] the front fillet radius of the number 3 main journal and there was a remark entered indicating possibility for rejection. The main and rod journals were then ground 0.010 inch undersize and renitrided. During the NTSB metallurgical examination a representative from ECI was contacted by phone to clarify additional information made on the work card. This representative indicated that the crankshaft passed 2 additional magnetic particle inspections on December 3, 1996 after the grinding process and on December 11, 1996 after the renitride process. The engine log book indicated that at about the same time period as the crankshaft overhaul, ECI repaired excessive fretting damage in the middle main bearing saddle of the crankcase." According to the NTSB form 6120.1/2, the airplane had accumulated about 9 hours of flight time since the overhaul of the crankshaft.