WPR15LA196

The private pilot reported that, while in cruise flight during the personal flight, the engine started to "sputter" and lose power. During troubleshooting efforts, the engine lost total power. The pilot then attempted to restart the engine without success and subsequently initiated a forced landing on a nearby beach. A postaccident engine examination revealed that the engine crankshaft would not rotate manually. Disassembly of the engine revealed evidence of wear and heat damage to the Nos. 1 and 2 crankshaft bearing halves. The oil filter contained no contaminants or metallic particles. No further evidence of a preexisting mechanical malfunction was noted during the examination of the engine and airframe. Damage to main bearings can occur from multiple sources, including oil contamination, excessive loads, or disruption of the lubrication between the bearing face and the main journal. Given that the Nos. 1 and 2 bearings were the only damaged bearings throughout the engine, it is unlikely that oil contamination caused the damage. In addition, given that the Nos. 1 and 2 bearings are located in the forward area of the engine and experience lighter loads than those located in the aft area of the engine, it is unlikely that excessive loads caused the damage. Although a propeller strike could result in an abnormal loading and lubrication of the bearings, a review of the airframe and engine maintenance records revealed no evidence of a reported propeller strike. Absent one of the above issues, it is likely that a disruption of the lubrication between the bearing face and the main journal resulted in the wear of the Nos. 1 and 2 bearing halves. However, no evidence of oil passage blockage, leaks, or excessive clearance between the bearings and the crankshaft journals was observed; therefore, the reason for the likely lubrication disruption or whether it caused the loss of engine power could not be determined. In addition, the accident bearings had an aluminum-tin intermediate layer, which makes the bearings less robust than those with a copper-alloy intermediate layer; thus, the wear and heat damage could have been preceded by delamination of the aluminum-tin intermediate layer. However, postaccident examination could not determine whether this occurred.

On June 22, 2015, about 0515 Pacific daylight time, a Piper PA-32R-301, N35590, experienced a total loss of engine power and landed on a beach of Lake Mead near Boulder City, Nevada. The airplane was registered to an individual, and operated by the pilot under the provisions of 14 Code of Federal Regulations Part 91 as a personal flight. The pilot and 3 passengers were not injured; the airplane sustained substantial damage. Visual meteorological conditions prevailed for the flight, which operated on a visual rules flight plan. The cross-country flight originated from North Las Vegas Airport, Las Vegas, Nevada, about 0430. The pilot reported that about 20 minutes after takeoff, with the airplane leveled off at an altitude of about 7,500 feet mean sea level, the engine started to "sputter". In the attempt to regain continuous power, the pilot adjusted the mixture control to rich; however, the propeller stopped spinning. The pilot tried to restart the engine twice but was unsuccessful. Subsequently, he initiated a forced landing onto a nearby beach. The airplane wreckage was examined at Air Transport, Phoenix, Arizona, on July 29, 2015, by representatives from Piper Aircraft, Inc., Lycoming Engines, and Federal Aviation Administration under the supervision of the National Transportation Safety Board (NTSB) investigator-in-charge. Primary flight control cable continuity was established from the rudder and elevator control surfaces to the cockpit controls, and to the wing roots from the yoke for the aileron actuation cables. The engine remained attached to the engine through all four mounts, hoses, wires, and control cables. All six cylinders remained attached to the engine. The two blade variable pitch propeller remained attached to the crankshaft. Neither blade sustained any damage. All engine accessories remained attached to the engine via their respective mounts. All fuel and oil lines were intact and undamaged. The crankshaft was not able to be manually rotated using the propeller. The engine was disassembled to allow for further examination. All six cylinders remained attached to their respective cylinder bays and were undamaged. Cylinders were removed from the engine and it was noted that the cylinder, valves, and rocker arms displayed normal operating and combustion signatures. All six piston faces displayed normal operating and combustion signatures; all of the piston rings were undamaged and were free to move in their respective grooves. There were no anomalies noted with the pistons. The crankshaft remained intact, and all the connecting rods remained free of heat distress. The No. 1 and No. 2 crankshaft bearing exhibited heat signatures at the aft thrust face. Their respective crankshaft thrust surface exhibited significant coloration consistent with an elevated thermal event. There was material transfer present on the thrust surfaces at each end of the bearing; more predominately at the aft portion of the bearing surface. The oil filterwas removed and visually inspected. There were no contaminates or metallic material noted in the filter. The oil suction screen contained a few small pieces of non-ferrous metal particles. The NTSB Material Laboratory examination of the No. 1 and No. 2 bearing halves showed substantial wear with missing Babbitt, exposing the underlying aluminum-tin intermediate layer. Black tint, scoring, and flowed metal was observed at the aft end of the No. 2 bearing interior, and metal particles from Babbitt were present at the chamfer at the forward edge of the No. 1 bearing. Post accident examination of the airframe revealed no evidence of mechanical malfunctions or failures that would have precluded normal operation. The complete engine and airframe examination report is appended to this accident in the public docket. A review of maintenance records showed that the most recent annual inspection was completed on July 24, 2014, at a total aircraft time of 3,136.18 hours and tachometer time of 1,718.68 hours. The last major overhaul was dated October 8, 1991, at a total aircraft time of 2,069.5 hours and tachometer time of 573.7 hours. The maintenance record indicated that the bearings were replaced at that time; however, it did not indicate which bearings were replaced.