On June 30, 2016, about 1230 eastern daylight time, a Hammer Challenger II CW experimental amateur-built single-engine airplane, N788RH, was substantially damaged during a forced landing following a total loss of engine power during initial climb at Union County Airport (MRT), Marysville, Ohio. The student pilot was not injured. The airplane was registered to and operated by the pilot as a Title 14 Code of Federal Regulations Part 91 personal flight. Visual meteorological conditions prevailed, and no flight plan had been filed for the local flight.

According to the pilot's accident report, after takeoff and during the initial climb, the engine lost all power. Since the airplane was still over the runway and the winds were calm, the pilot made a left turn in an attempt to land on a grass runway parallel to the departure runway. The pilot made "a hard semi-controlled landing." Post-accident examination revealed the left main landing gear and wing strut were bent, and the left wing tip was crumpled. Further examination revealed a spark plug had blown out of the 2-cylinder engine.