On September 1, 2017, about 1515 mountain daylight time, a Cessna 310G airplane, N8957Z, sustained substantial fuselage damage during a landing gear collapse while landing on runway 30R at the Rocky Mountain Metropolitan Airport (BJC), near Broomfield, Colorado. The pilot and passenger were not injured. The airplane was registered to and operated by Zero Energy Aviation, LLC under the provisions of Title 14 Code of Federal Regulations Part 91 as a training flight. Visual meteorological conditions prevailed for the flight, which operated on a visual flight rules flight plan. The flight originated from the Boulder Municipal Airport (BDU), Boulder, Colorado, about 1315 and the intended destination was the Greeley-Weld County Airport (GXY), Greeley, Colorado. The pilot reported that during approach to GXY, he lowered the landing gear and noted a that the green gear-down indicator illuminated. Upon touchdown, he felt a "mushy feeling" and aborted the landing, leaving the landing gear in the down position. He noted that the gear-down indicator was still illuminated. He attempted another landing with the same result and initiated another aborted landing, again leaving the landing gear in the down position. At this time neither the red gear-up light nor the green gear-down light were illuminated. The pilot left the landing gear in the down position and proceeded toward BDU, which was the airplane's home base. He attempted to contact ground personnel at BDU to assist in verifying the landing gear position. There was no response on the common traffic advisory frequency (CTAF), and he elected to contact the air traffic control tower (ATCT) at BJC. After establishing communication with BJC ATCT, he performed several fly bys of the tower and tower personnel confirmed that the right main landing gear was not fully extended. After making another attempt to lower the landing gear using the emergency checklist, the pilot landed on runway 30R. During the touchdown, the landing gear collapsed. According to the pilot, maintenance personnel found that the pushrod extending from the gear motor to the right main landing gear was found bent. The reason for the bent pushrod was not determined. Federal Aviation Administration records indicated that the pilot held a private pilot certificate with an airplane single engine land rating. He did not hold a multiengine rating. The airplane was a twin-engine retractable-gear airplane.