On September 24, 1999, about 1428 eastern daylight time, a Cessna 172RG, N9536B, registered to Claire Plane Inc., and operated by Orlando Aero Club, crashed on landing at Orlando Executive Airport, Orlando, Florida, while on a Title 14 CFR Part 91 instructional flight. Visual meteorological conditions prevailed at the time, and an instrument flight rules flight plan was filed. The aircraft received substantial damage, but the airline transport pilot-rated flight instructor and student sustained no injuries. The flight originated from St. Petersburg, Florida, the same day, about 1315. The flight instructor stated that after leaving St. Petersburg, he experienced interference with the aircraft radios which the squelch would not eliminate. The instructor also stated that the alternator tripped off line, and he could not reset it, so he turned the master switch off, and continued the flight to his planned destination. The instructor further stated that upon reaching the destination airport and preparing to land, he turned on the master switch, extended the landing gear, visibly checking that the left gear was down, but did not get a gear light. The instructor stated that the battery had tripped off line, but thinking that the gear was down, he proceeded to land the airplane. During the landing, the right main gear settled to the runway and gave way, with the airplane exiting the runway to the right. The instructor stated that he never attempted to manually pump the gear down. The FAA inspector who conducted the postcrash examination of the accident airplane stated that he found the accident airplane with the left main gear extended and locked, the nose wheel sheared off, and the right main landing gear collapsed and in its gear well. The FAA inspector also stated that witnesses reported to him that they saw the right main gear trailing just prior to landing. The inspector further stated that the aircraft battery was almost depleted of electrical energy, and that the low voltage warning light was activated. According to the inspector, thirty degrees of flaps was selected, but the flaps were only extended about 10 to 15 degrees, and the manual extension pump for the landing gear was stowed, with no evidence of recent use. The inspector said that after supporting the aircraft and starting the engine, no electrical problems were found with the airplane.