On April 10, 2022, about 1108 eastern daylight time, an experimental, amateur-built Lancair IVP, N7KJ, was substantially damaged when it was involved in an accident near Leicester, Massachusetts. The pilot and passenger were not injured. The airplane was operated as a Title 14 Code of Federal Regulations Part 91 personal flight. According to the pilot, about 40 minutes after departure, during a cross-country flight at 16,500 ft mean sea level, there was a “sudden explosion and the right window was gone.” He performed an emergency descent and landed uneventfully. He noted that during the flight there were no pressurization issues before the window separated from the airplane. Examination of the airplane by a Federal Aviation Administration (FAA) inspector revealed that the right front window and portions of the roof fractured and separated from the fuselage, resulting in substantial damage (see Figure 1.) Figure 1- View of missing right front window and roof structure. (Photo courtesy of FAA) The separated window was not located; however, a FAA inspector initially documented the airplane. Before a detailed examination could be completed, repairs were made on the airplane and the original fracture surfaces were not available for examination. No maintenance records were provided. The pilot/owner stated he had ordered replacement windows, but the accident occurred before he could get them installed.