On February 17, 2018, about 1500 mountain standard time, a Cozy III experimental amateur-built airplane, N904DB, was substantially damaged during a forced landing after an in-flight propeller gearbox failure at the Mid Valley Airpark (E98), Los Lunas, New Mexico. The commercial pilot was not injured. The airplane was privately owned, and operated by the pilot as a Title 14 Code of Federal Regulations Part 91 personal flight. Visual meteorological conditions prevailed throughout the area and no flight plan was filed for the flight. The flight originated from E98 about 1400. After flying uneventful for about 1 hour in the local area, the pilot set up for landing at E98. On downwind for runway 36, the propeller seized and the pilot executed a forced landing to runway 36. While turning on final approach, the pilot slightly overshot the runway and touched down hard on the right edge of the runway. The landing gear were sheared upon touchdown and the airplane sustained substantial damage to the right wing and center fuselage section. Examination of the airplane revealed that the propeller gearbox was seized. Examination of the gearbox did not reveal any obvious reason for the seizure. Logbooks indicated that the airplane and engine total hours were about 13.4 since it's initial airworthiness certificate was issued on July 5, 2012.