History of Flight
On May 9, 2015, at approximately 1015 Pacific daylight time, a Piper PA32-300 Cherokee Six, registration N4124R, performed a forced landing following a complete loss of engine power at Redlands Municipal Airport in Redlands, California. The aircraft was operated by Kamasano, LLC under 14 Code of Federal Regulations Part 91. The commercial pilot and four passengers were not injured, but the airplane sustained substantial damage. The personal cross-country flight had originated from Redlands and was destined for Oceano County Airport in Oceano, California. Visual meteorological conditions prevailed, and a visual flight rules flight plan was filed.
According to a written statement from the pilot, about 30 seconds after takeoff, while the airplane was 250 feet above ground level, the engine began to emit an unusual sound and the pilot felt a vibration. The cockpit gauges displayed normal indications, but the noise was disconcerting. The pilot decided to land immediately. With obstacles and boulders ahead, he turned back toward the airport, executed a steep turn, and descended rapidly while the engine only produced partial power. Unable to maintain altitude, the airplane cleared the airport's perimeter fence and touched down hard on runway 08. The propeller contacted the asphalt, and the engine stopped. The pilot then swerved onto the gravel median to avoid oncoming traffic, and the right wing impacted a runway sign, resulting in substantial damage.
A preliminary engine examination revealed 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 was a Textron Lycoming IO-540-K1A5, serial number L-5528-48. A review of the maintenance logbooks showed that the last annual inspection occurred on November 3, 2014, at which time the engine had accumulated 4,911.6 total hours and about 465 hours since its last major overhaul. A notation indicated that AVBLEND was added to the oil system during that inspection. The most recent maintenance on March 30, 2015, included installation of a new starter and an oil change. The oil cooler had been replaced in March 2014.
Engine Examination
An external examination of the engine revealed that it remained attached to the airframe on all mounts. A hole was found in the crankcase between cylinders number 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 number three and five cylinder bays.
Examination of cylinders number one, two, five, and six showed no evidence of foreign object damage or mechanical malfunction; the intake and exhaust valve faces were intact. The connecting rods for cylinders one and two were intact and undamaged. The rods for cylinders three and four were separated from the crankshaft, with the rod caps separated, and exhibited mechanical and thermal damage. The rods for cylinders five and six remained intact but displayed severe thermal discoloration, and portions of their rod bearings were partially extruded from the rod cap.
The oil pressure relief valve was removed from the crankcase; the internal spring and ball remained intact, and there were five washers in the assembly. A review of the Lycoming Overhaul Manual, Section 9, item 9-23, stated that the oil pressure relief valve is non-adjustable, but oil pressure can be controlled by adding up to a maximum of three STD-425 washers under the cap to increase oil pressure.
The oil cooler, stamped Aero-Classics Heat Transfer Products, part number 8000074, had been previously removed and appeared visually 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 oil would seep from the cooler under operating conditions.