On May 29, 2001, at 0715 central daylight time, a Cessna 421, N51ER, experienced a flight control problem while in cruise flight and executed an emergency descent and landing at the Mid Delta Regional Airport (GLH) in Greenville, Mississippi. The personal flight was conducted by the pilot under provisions of Title 14 CFR Part 91 with an instrument flight plan filed. Visual weather conditions prevailed at the time of the accident. The airplane was substantially damaged. The air transport pilot and seven passengers were not injured. The flight departed Springdale Municipal Airport (ASG) in Springdale, Arkansas, at 0600, en route to Destin, Florida. The pilot stated, about 45 minutes into the cruise flight at 19,000 feet, there was a "loud pop" accompanied by instantaneous shaking of the control yoke. The pilot disengaged the autopilot and noticed the airplane had begun a descent. The pilot advised Memphis center of the problem and received vectors to the nearest airport, Mid Delta Regional. The pilot reported that the airplane was flying in a nose-down attitude with a descent rate of 1,200-1,500 feet per minute. The pilot utilized full-aft elevator and increased power to bring the airplane's nose to a "more controlled attitude." The pilot reported, upon reaching the airport, the airplane was too high, so the pilot circled the airport twice before entering a final approach for runway 36R. Because of the nose-down pitching tendency of the airplane, the pilot decided not to deploy the landing gear or the flaps. The pilot added power and held full-aft elevator in an attempt to flare the airplane. The airplane came to a full stop on the runway. Examination of the airplane revealed the inboard half of the right elevator trim tab was not attached to the right elevator. The push-pull rod was not connected to the right elevator trim tab horn, and the bolt and hardware that connects the push-pull rod to the right elevator trim tab horn were missing. The trim actuator rod was bent. The airplane's records revealed that the flight controls had been recently removed for painting and were signed off by a mechanic at the painting company on May 11, 2001. During painting, the airplane's registration number was changed from N543PM to N51ER. The records also revealed that the elevator trim was adjusted and signed off by a mechanic on May 22, 2001. No previous record of control surface malfunction was revealed during the review of the airplane maintenance records.