On April 5, 1998, approximately 1000 mountain daylight time, a Cessna T210L, N591DC, was substantially damaged during a forced landing 4 miles south of Santa Teresa, New Mexico. The private certificated instrument rated pilot receiving instruction and the airline transport rated flight instructor received minor injuries. Visual meteorological conditions prevailed, and no flight plan was filed for the instructional flight being conducted under Title 14 CFR Part 91. The flight originated at Santa Teresa, New Mexico, approximately 0800. According to the accident report submitted by the pilot, he was receiving an instrument competency check from the flight instructor. He and his instructor departed Santa Teresa, flew to Deming and Silver City, New Mexico, where instrument approaches were conducted. They were returning to Santa Teresa and were on an "extended let-down from 50 nm out at 23 inches of manifold pressure, 2,300 rpm, and 130 knots indicated airspeed." There was a loud noise, they caught a glimpse of something shoot out from the cowling, then there was a "sudden loss of power, severe engine vibration, and light blue smoke in the cockpit." The pilot landed on a dirt road 1.5 miles northwest of Santa Teresa, struck a sand dune, bounced, and nosed over. The engine was examined on April 22, 1998, by an FAA inspector and a representative of the engine manufacturer. The no. 1 piston was broken in half. The top half remained inside the upper portion of the no. 1 cylinder. The bottom half was destroyed. The connecting rod and the cap bolt were separated. The camshaft and its splined end (where it attaches to the oil pump) were damaged, and the oil pump had seized. There was "necking down" of the rod cap bolts, consistent with tension overload. According to the maintenance records, the engine was installed in a new airplane, N1788X, on March 28, 1975. The engine had accrued 549.6 total hours when it was removed from the airplane, overhauled, and installed in N591DC. At the time of the accident, the engine had accumulated 1,464.7 total hours, or 915.1 hours since major overhaul.