On May 4, 2002, at 0810 eastern daylight time, a Cessna 310L, N1199L, owned and piloted by a private pilot, sustained substantial damage when the landing gear collapsed while landing on runway 33 (5,090 feet by 100 feet, dry/asphalt) at the Detroit City Airport (DET), Detroit, Michigan. Visual meteorological conditions prevailed at the time of the accident. The personal flight was operating under the provisions of 14 CFR Part 91 on an instrument flight rules (IFR) flight plan. The pilot and his two passengers reported no injuries. The flight departed DET at 0735 and was returning due to an in-flight electrical system failure. According to the pilot's written statement, the flight was intended to be a cross-country to Dekalb-Peachtree Airport (PDK), Atlanta, Georgia. The pilot reported that when he was handed-off to Toledo approach control he noticed that the instrument lights were blinking off and on. The pilot stated he informed Toledo approach control that he was having electrical problems and wanted to return to DET. The pilot reported while returning to DET the airplane lost all electrical power. The pilot stated, "Upon arriving at DET we hand crank[ed] the landing gear down, the landing gear did not lock." The pilot reported that during the landing the nose and main landing gear collapsed and the airplane swerved off the runway. According to the Cessna 310L Pilot Operating Handbook (POH), when the landing gear does not extend electrically the pilot is to rotate the emergency landing gear hand crank, "Clockwise four turns past point where gear down lights come on (approximately 52 turns)."