On April 14, 2002, about 2045 Pacific daylight time, a Cessna 172, N211CA, lost engine power and collided with the ground during an off airport forced landing at Lake Los Angeles, California. First Class Air Service, Van Nuys, California, operated the airplane under the provisions of 14 CFR Part 91. The private pilot and passenger both received minor injuries. The airplane was substantially damaged. Visual meteorological conditions prevailed at the departure point for the personal flight, and no flight plan had been filed. The flight originated at Apple Valley, California, about 2030, and was destined for Van Nuys. Post accident examination of the engine revealed that the No. 3 engine cylinder steel barrel had separated 360 degrees around its circumference. Examination of maintenance records revealed replacement of the No. 3 cylinder and piston rings on March 24, 2002, at 3,930.36 recording tachometer hours. A Federal Aviation Administration Approved Repair Station had repaired the cylinder. The tachometer time at the accident site was 3,941.62. Close examination of the failed cylinder barrel revealed fatigue cracking originating from a rusty area on the cylinder barrel. Additionally, cooling fin rust damage had the appearance of having been profiled by filing or grinding.