HISTORY OF FLIGHT On May 09, 2015, about 1015 Pacific daylight time, a Piper PA32-300 Cherokee Six, N4124R, made a forced landing following a total loss of engine power at the Redlands Municipal Airport, Redlands, California. Kamasano, LLC. was operating the airplane under the provisions of 14 Code of Federal Regulations (CFR) Part 91. The commercial pilot and four passengers were not injured; the airplane sustained substantial damage. The personal cross-country flight was originating from Redlands with a planned destination of Oceano County Airport, Oceano, California. Visual meteorological conditions prevailed, and a visual flight rules (VFR) flight plan had been filed. In a written statement, the pilot reported that about 30 seconds after takeoff, while the airplane was 250 feet above ground level (agl), the engine began to emit an unusual sound, and he felt a vibration. He noted that the cockpit gauges all displayed normal indications although the noise was disconcerting. The pilot opted to land immediately, and with obstacles and boulders in front of him, he turned back toward the airport. He completed a steep turn, and descended rapidly with the engine only producing partial power. Unable to maintain altitude, the airplane just cleared the airport's perimeter fence, and the airplane touched down hard on runway 08. The propeller contacted the asphalt, and the engine stopped. The pilot further stated that he swerved onto the gravel median to avoid oncoming traffic. The right wing impacted a runway sign resulting in substantial damage. A preliminary engine examination revealed that there was a hole in the engine case near the number four cylinder. Oil streaks were found near the taxiway and run-up area. AIRCRAFT INFORMATION The Piper PA32-300, serial number 32-40442, was manufactured in 1968. The engine's data plate indicated it was a Textron Lycoming IO-540-K1A5 engine, serial number L-5528-48. A review of the airplane maintenance logbooks revealed the last annual inspection occurred on November 3, 2014 at which time the engine had accumulated 4,911.6 hours total time, and about 465 hours since the last major overhaul. There was a notation that the mechanic added AVBLEND to the oil system at this time. The records indicated that during the last maintenance on March 30, 2015, the mechanic installed a new starter and changed the oil. The oil cooler was replaced in March 2014. TEST AND RESEARCH An external examination of the engine revealed that it remained attached to the airframe on all the engine mounts. There was a hole in the crankcase located between cylinders no. four and six extending from the cylinder bay upward to the crankcase backbone. A crack in the crankcase extended from the backbone to an area between the no. three and five cylinder bays. An examination of the no. one, two, five, and six cylinders revealed no evidence of foreign object damage or mechanical malfunction. The intake and exhaust valve faces were intact. The no. one and two connecting rods were intact and undamaged; the no. three and four connecting rods were separated from the crankshaft with the rod caps separated. The connecting rods exhibited mechanical and thermal damage. The no. five and six connecting rods remained intact, however, they exhibited severe thermal discoloration. Portions of the no. five and six connecting rod bearings were partially extruded from the rod cap. The oil pressure relief valve was removed from the engine crankcase. The internal spring and ball remained intact; there were five washers in the assembly. A review of the Lycoming Overhaul Manual, Section 9, item 9-23, stated in part "…non-adjustable oil pressure relief valve – Although the valve is not adjustable, the oil pressure can be controlled by the addition of STD-425 washers under the cap as required (maximum of three) to increase oil pressure..." The oil cooler, stamped Aero-Classics Heat Transfer Products, part number 8000074, was previously removed and visually appeared intact. When compressed air was applied to one of the ports, air expelled from the side of the oil cooler, where there was a small gap between mating brazed plates. It could not be determined the rate at which the oil would seep from the oil cooler when the system was operating.