On December 13, 2015, about 1633 eastern standard time, a Cessna 310Q, N7675Q, operated by a private individual, was substantially damaged following a collapse of the left landing gear during landing roll at Cobb County Airport-McCollum Field, Kennesaw, Georgia. The private pilot and a passenger were not injured. Visual meteorological conditions prevailed and no flight plan was filed for the local flight. The personal flight was operated under the provisions of Title 14 Code of Federal Regulations Part 91. According to the pilot, he was cleared to land on runway 27, a 6,200 foot-long, by 100 foot-wide, concrete runway. He lowered the landing gear on downwind leg and observed three green indicator lights. After touchdown and during the landing rollout, the gear warning light illuminated and horn activated twice. The airplane continued to decelerate and was three quarters the way down runway 27, at a speed of around 35 knots, when the left landing gear collapsed. It then swerved to the left, departed the runway, and came to rest in the grass adjacent to the runway. The airplane sustained damage to the left wing, left horizontal stabilizer, and the bottom of the fuselage near the tail section, left elevator, and left aileron was bent. Examination of the airplane by an Federal Aviation Administration inspector revealed that the left main landing gear down lock bellcrank was fractured and had separated from its respective trunnion. The bellcrank bolt was sheared at the bolt head consistent with overload. The trunnion forward attach point for the bellcrank was broken and not recovered. The upper end of the bellcrank remained attached to the outboard push-pull tube. The lower end of the bellcrank, which attached to the rod end fitting at the lower side link was broken consistent with a ductile tension failure. Damage to the landing gear precluded the ability to functionally check or verify the landing gear system rigging. According to a representative from Cessna, the fracture location would be consistent with the additional stresses that would have been placed on the bellcrank with the landing gear having not been properly rigged. During an annual inspection, the down lock tension check is to be performed to verify the landing gear is adjusted correctly and locks in the down position. Review of maintenance records revealed that the airplane had been operated for about 16 hours since its most recent annual inspection, which was performed on December 1, 2014. The maintenance log book records do not reflect that the landing gear system was checked.