WPR21LA030 · Cessna 310 R

The pilot departed in the twin-engine airplane for the cross-country flight. About 1 mile south of the airport, at an altitude of 2,800 ft, the pilot requested a destination change from air traffic control to a nearby airport. The pilot further requested a direct heading to the airport and stated he needed to shut down one engine. As the airplane flew toward the new destination airport, a witness observed the airplane fly over powerlines and then pitch down. The airplane maintained its altitude briefly then nosed down again before it rolled sharply to the left. The airplane impacted the ground about 8 nautical miles northwest of the airport and a postcrash fire ensued. The witness stated that the left engine appeared to be inoperable as the propeller was not spinning. Recorded footage from a witness video confirmed the lack of power from the left engine and power being produced on the right engine. Recorded automatic dependent surveillance–broadcast data indicate the airplane’s airspeed was approximately 86 knots at the time the turn to the new destination airport was initiated. The airspeed briefly increased to 97 knots over the next minute then gradually decreased to a final airspeed of 78 knots when the data was lost. The airplane’s minimum controllable airspeed (VMC) was 80 knots; therefore, as the airspeed decreased below VMC, the pilot was likely unable to maintain control of the airplane while maneuvering with one engine inoperative. A postaccident examination of the left engine revealed two holes in the crankcase above cylinder Nos. 3 and 4. The No. 2 connecting rod was separated from the crankshaft and no indication of lubrication was noted in the crankcase. The lack of lubrication, combined with signatures of thermal damage on many of the crankshaft journals and bearings, indicated the likelihood of an oil pressure problem, which resulted in a loss of engine power. About 10 months before the accident, the engine was disassembled and inspected for a low oil pressure problem. During the maintenance, the main bearings and rod bearings were replaced, as well as the alternator, oil cooler, and starter adapter. The airplane flew about 40 hours after the maintenance was completed; an annual inspection was performed about 6 months before the accident. During the inspection, cylinder compression was noted between 61-65 pounds per square inch (psi) on each cylinder. FAA guidance states cylinder compression less than 60 psi requires removal and inspection of the cylinder. While the cylinder compressions were just above the limit requiring removal, their low compression readings should have indicated a problem to maintenance personnel that needed to be addressed. The low compression readings only 40 hours after engine disassembly and the failure to identify or correct the reason for the low compression indicates inadequate maintenance. Toxicology testing detected ethanol in the pilot’s liver and muscle tissue but not in his brain tissue. The ethanol concentration in his liver was over ten times higher than the concentration detected in his muscle tissue. Extensive trauma increases the risk of postmortem ethanol production. Given the differing ethanol tissue concentrations and the trauma received by the body from the crash, it is likely that the identified ethanol was from sources other than ingestion. Thus, the identified ethanol did not contribute to the accident. Additionally, although toxicology testing detected the sedating antihistamine diphenhydramine in the pilot’s urine and liver tissue, the amounts were too low to quantify. Based on the circumstances of this accident, including the pilot’s appropriate decision to land after an engine failure, it is unlikely that effects from the pilot’s use of diphenhydramine contributed to this accident.

Verbatim NTSB analysis and probable cause from the NTSB dataset