On November 5, 2004, at approximately 1430 mountain standard time, a Mooney, N2695W, piloted by a commercial pilot, was substantially damaged when it impacted a road sign during a forced landing on Highway 54, north of Santa Rosa, New Mexico. Visual meteorological conditions prevailed at the time of the accident. The personal flight was being conducted under the provisions of Title 14 CFR Part 91 without a flight plan. The pilot was not injured. The cross-country flight originated at Miami, Oklahoma, and was en route to Tucumcari, New Mexico. According to the accident report submitted by the pilot, he had purchased the accident airplane in August of 2003. The pilot requested an inspection to be conducted by Broken Arrow Aviation in Miami, Oklahoma, to ensure there was "no corrosion." The annual inspection was performed on October 3, 2004. The pilot left Miami on the date of the accident. During his flight, the pilot attempted to land at Amarillo, Texas; however, he was unable to establish radio contact with them and elected to continue on to Tucumcari, New Mexico. When the pilot arrived in Tucumcari, he was unable to extend his landing gear and had to "crank the gear down." The airplane was refueled and while preparing to depart, the pilot stated that the airplane's "battery seemed weak" and noted that the ammeter was not charging or discharging. The pilot had the battery charged for 1/2 hour and elected to fly to Double Eagle Airport, Albuquerque, New Mexico, where he had arranged to have a mechanic examine the airplane. The pilot departed Tucumcari and upon passing Santa Rosa, he noticed "the engine was running rough." The pilot checked both magnetos and noted the left magneto selection resulted in a rough engine. The fuel pressure was also low; however, the pilot felt he would be okay until arriving in Albuquerque. The pilot stated that both magnetos began to run rough and he attempted to return to Santa Rosa. He was unable to maintain altitude and landed on Highway 54. While maneuvering the airplane to avoid oncoming traffic, the airplane struck a road sign. The outboard 24 inches of the leading edge of the right wing was crushed aft. The four outer ribs of the right wing were fractured and bent. According to the FAA inspector who traveled to the scene, examination of the engine revealed that the P-lead had broken off of the right magneto. The P-lead had been rubbing against a bracket aft of the P-lead, prior to its failure. The FAA inspector stated further that an annual inspection should have discovered this situation.