On July 25, 2004, about 1150 Pacific daylight time, a Piper PA-32RT-300, N5GC, operated by the pilot-owner, experienced a total loss of engine power while cruising. The pilot made a forced landing in a field about 3/4-mile east of the Ontario International Airport, Ontario, California. Following touchdown, the airplane impacted a berm and was substantially damaged. Neither the airline transport pilot nor the passenger was injured. Visual meteorological conditions prevailed at the time of the personal flight, and no flight plan had been filed. The local flight was performed under the provisions of 14 CFR Part 91, and it originated from Upland, California, about 1130. The pilot reported to the National Transportation Safety Board investigator that initially during his flight the engine seemed to be operating normally. After flying for several minutes the engine started running rough, and oil appeared on the front windshield. Thereafter, all engine power was lost. The airplane had insufficient altitude to glide to the nearest airport, and a forced landing ensued in a field. Under the Safety Board investigator's direction, the airplane was recovered from the accident site and was examined under the supervision of a Federal Aviation Administration (FAA) aviation safety inspector. The external engine examination revealed the presence of a hole in the engine's case, next to the oil dipstick port. The engine was removed from the airplane and disassembled by personnel at a FAA certificated repair station, while under FAA supervision. In pertinent part, the repair station personnel reported its examination observations and opined the following sequence of events: 1. The engine was noted to have approximately 10 quarts of oil in the sump; 2. The oil pan and finger screen were full of metal; 2. Connecting rod bearing, part number SL74309, on connecting rod number 5 appeared to have overheated to failure; 3. This overheat condition resulted in breakage of connecting rod number 5; 4. Debris from this breakage resulted in connecting rod number 6 punching a hole in the case. According to the pilot-owner, he had recently purchased the airplane, which had a total time of 6,325.38 hours. The engine, serial number L17809-48A, had 806 hours since last receiving a major overhaul. The airplane had been operated about 40 hours since its last annual inspection in November 2003.