On July 4, 2002, about 1330 eastern daylight time, a Cessna 340A, N15FH, registered to and operated by a private individual, as a Title 14 CFR Part 91 personal flight, made a forced landing at Flagler County Airport, Bunnell, Florida. Visual meteorological conditions prevailed, and no flight plan was filed. The airplane incurred substantial damage, and the airline transport-rated pilot and one passenger, received no injuries. The flight originated from Bunnell, Florida, the same day, about 1315. The pilot stated that he was conducting a test flight after the airplane's annual inspection, and he had flown for about 10 minutes, prior to returning to the airport. Upon his return to the airport for landing, he said he noted the absence of a "down and locked" indication for the right main gear, so he cycled the landing gear twice, and contacted airport operations to request a "fly by", so that an external examination of the landing gear could be made. He said that the "fly by," revealed that the landing gear appeared to be "down and locked", and he then departed the pattern to perform the emergency gear extension checklist, but still could not obtain a positive right main landing gear "down and locked" indication. He then returned for landing, and when all three landing gears touched the runway, the right main gear collapsed. The right propeller and wing tip contacted the ground, and the airplane departed the runway to the right, impacting taxiway lights before coming to rest, having incurred damage to its right wing, propeller, and tail section. An FAA Inspector who conducted a postaccident examination of the airplane said that the right main landing gear extension tube had broken due to a weak/stretched over center spring.