What happened
During the flight, the pilot reported that the airframe began accumulating moderate to severe mixed ice after descending to a lower altitude. In response, the pilot activated the de-icing boots and turned on the windshield heat. After climbing back to a higher altitude, most of the ice cleared, and the pilot was cleared for an ILS approach.
The aircraft broke out of the clouds approximately 400 feet and 1/4 mile from the runway. As the aircraft was positioned over the runway numbers, roughly ten feet above the surface, it experienced an unexpected stall. Although the pilot applied full power, the right main landing gear made a hard touchdown, and the right wing tip contacted the runway surface. The pilot successfully completed the landing and taxied the aircraft to a hangar.
Findings
Upon exiting the aircraft, the pilot observed that much of the airframe remained covered in moderate to severe ice. This accumulation included the leading edges of the vertical and horizontal stabilizers as well as the propeller spinner.