On August 11, 2005, about 1259 Pacific daylight time, an Agusta SPA, SF.260D, N402FD, experienced the separation of its canopy during descent for landing at the Redding Municipal Airport, Redding, California. The airplane was substantially damaged, and the commercial pilot was not injured. The airplane was owned and operated by Air Combat USA, Inc., Fullerton, California. Visual meteorological conditions prevailed at the time of the work-related flight, and no flight plan had been filed. The flight was performed under the provisions of 14 CFR Part 91, and it originated from Fullerton about 1000. The pilot reported to the National Transportation Safety Board investigator that between 8 and 10 miles from Redding the entire canopy separated from the airplane. Also, the helmet he was wearing came off his head, and baggage exited the airplane. The pilot was unable to contact the Redding control tower, so he changed to the emergency transponder code. Thereafter, he received a green light signal from the control tower, and he landed without further mishap. The pilot indicated that he had not experienced any malfunction with the canopy's operation when he initiated the flight. He stated that when the canopy separated its latch was in the closed position. Company personnel reported to the Safety Board investigator that their search for the separated canopy was unsuccessful. An examination of the airplane revealed that the leading edge of the left horizontal stabilizer was crushed inward over approximately a 1-foot-long span. Also, the leading edge of the vertical stabilizer was similarly crushed in an aft direction. According to company personnel, this was the first flight following the company's removal and reinstallation of a serviceable canopy. A company mechanic opined that this procedure to reinstall a canopy involved checking that the canopy's locking pins were positively engaged in the support lugs on the airframe. The mechanic indicated to the Safety Board investigator that this verification procedure had evidently not been complied with by the mechanics who had installed the canopy.