CEN19LA290

The private pilot and passenger were en route on an instrument flight rules flight when the engine lost oil pressure, followed by a total loss of engine power. The pilot declared an emergency with air traffic control and stated that he “had an oil pressure event there but it’s building back up so standby.” The controller cleared him direct to the nearest airport and asked the pilot if he need any assistance at the airport, which the pilot declined. Flight track data showed that the airplane began a shallow descent toward the diversion airport before the data ended about 2 minutes later. The pilot stated that he flew directly over the airport and was unable to see it due to oil on the windshield and smoke in the cabin; he eventually performed a forced landing in a field about 4 nautical miles from the diversion airport. A postaccident disassembly examination revealed a large hole in the top of the engine crankcase above the No. 6 cylinder. The inside of the engine contained a significant amount of metallic debris. The Nos. 1 through 4 connecting rods remained attached to the crankshaft, but all exhibited significant heat distress from a lack of oil lubrication. The Nos. 5 and 6 connecting rods fractured at the bearing and sustained damage from impacting the crankshaft, cylinder walls, and the inside of the case. The ends of the Nos. 5 and 6 connecting rods and their bearings were not found or identified within the available metallic debris. It is likely that the Nos. 5 and 6 connecting rods failed due to a lack of oil lubrication; however, the reason for the oil loss could not be determined. The continued operation of the engine after the loss of oil pressure likely contributed to and aggravated the amount of damage to the engine.

A review of the airplane maintenance logbooks revealed that in 1993, at a tachometer time of 2,001 hours, the engine underwent a major overhaul in accordance with the Continental Motors overhaul manual and applicable service bulletins. New Continental Motors cylinder assemblies were installed (part number 653445A1). New piston pins were installed, but the part number and serial number were not specified. In December 2012, at 693.2 hours since major overhaul (SMOH), the engine was removed from the airplane for a “tear down inspection following oil starvation engine shutdown.” The pilot stated that the oil starvation event was caused by “a broken oil line.” The work order stated that the “engine was disassembled, cleaned, inspected, and repaired due to loss of oil.” The engine was repaired and reinstalled on the airplane in February 2013. The maintenance facility’s engine “preliminary inspection record” noted that the crankshaft and the main and rod bearings were replaced. Since the engine repair in 2013, the engine had undergone four annual inspections and accumulated 1,189.56 hours SMOH. The final engine maintenance logbook entry was for an oil and oil filter change, dated June 25, 2019, at 1,882.76 hours SMOH. The pilot provided records of regular engine oil analysis from June 19, 2009, to June 26, 2019. All 27 samples were normal, including the most recent sample, taken 33.6 hours prior to the accident. Engine Data Monitor (EDM) The airplane was equipped with a JPI EDM 830 which was sent to the NTSB Vehicle Recorder Division for download; however, no data could be recovered from the device. On August 27, 2019, about 1206 central daylight time, a Beech V35 airplane, N6245V, was substantially damaged when it was involved in an accident near Monroe, Wisconsin. The private pilot sustained minor injuries and the passenger sustained serious injuries. The airplane was operated as a Title 14 Code of Federal Regulations Part 91 personal flight. The pilot and passenger were about 48 minutes into the flight instrument flight rules (IFR) flight when the engine suddenly lost oil pressure. The pilot was in communication with air traffic control, declared an emergency, then stated that he, “had an oil pressure event there but it’s building back up so standby.” The pilot requested to deviate to a nearby airport. The controller instructed the pilot to descend and issued a heading of 050° toward the airport. The controller then asked the pilot if he need any assistance, to which the pilot replied, “we’re OK at this time.” The controller issued a frequency change and told the pilot to report his IFR cancellation. The pilot then requested to cancel his IFR flight plan, and the controller terminated radar services. There were no other recorded transmissions from the pilot. The pilot reported after the accident that, after he declared the emergency, the airplane was at 5,000 ft (4,000 ft agl). The pilot added that after he canceled his IFR flight plan, engine oilbegan to cover the windshield and smoke entered the cabin. He switched to the diversion airport’s common traffic advisory frequency and spoke with a pilot who had just departed. The recorded automatic dependent surveillance – broadcast (ADS-B) data showed that the airplane started a shallow descent and proceeded directly toward the diversion airport (figure 1). About 2 minutes later, at 1201:03, the ADS-B data ended about 1.5 nautical miles (nm) southwest of the airport and about 3,200 ft above ground level (agl). Figure 1. Google Earth image depicting the flight track toward the airport and accident site. According to the pilot, he was unable to locate the airport due to the smoke in the cabin and the oil on the windshield. He knew that he had passed it, but since the airplane was rapidly losing altitude, he knew he did not have enough altitude and airspeed to turn back. He then identified a rural road as a forced landing site. Due to power lines and telephone poles along the road, he instead continued into a cornfield, where the airplane landed hard. The airplane impacted a mature cornfield, rotated 180°, slid backward, and came to rest upright. The fuselage remained intact, and the engine was impact separated from the firewall. Both wingtips sustained impact damage. The responding Federal Aviation Administration (FAA) inspector reported that there was a hole on the top of the engine crankcase and metallic debris inside the case. The oil filter remained installed, and the safety wire was tight. The oil lines remained intact and there was no evidence of a loose line. The hole was located in the top of the crankcase above the No. 6 cylinder. The Nos. 5 and 6 cylinder connecting rods were broken so the engine could not be rotated. There was repeated impact marks and damage to the inside of the case around the Nos. 5 and 6 cylinders. The Nos. 1 through 4 connecting rods remained attached to the crankshaft, but all exhibited heat distress from a lack of oil lubrication. The Nos. 5 and 6 connecting rods had fractured at the crankshaft bearing end and sustained damage from impacting the crankshaft, cylinder walls, and the inside of the case. The ends of the Nos. 5 and 6 connecting rods and their bearings were not found or identified within the available metallic debris; both rods exhibited heat damage and lack of oil lubrication. The Nos. 5 and 6 pistons remained attached to the connecting rods via the piston pins.