Accident Overview
On June 30, 2017, at approximately 1105 Pacific daylight time, a Cirrus Design Corporation SR-22, registration N744TC, was substantially damaged during an accident near Dixon, California. The private pilot and a passenger were not injured. The flight was conducted under Title 14 Code of Federal Regulations Part 91 as a personal flight.
Pilot Report
The pilot reported that after departing from San Jose, California, he climbed to 7,500 feet and leaned the engine for cruise. He noticed the manifold pressure was lower than usual but the engine sounded normal and all instruments were within the green. About 30 minutes later, during descent to Yolo County Airport in Davis, California, the oil pressure reading rapidly dropped. The engine then lost all power and emitted a loud bang, followed by oil spraying onto the windscreen, obstructing visibility. The pilot deployed the Cirrus Airframe Parachute System (CAPS) and descended into a vineyard. One main landing gear penetrated and substantially damaged a wing.
Engine Examination
Postaccident examination of the engine revealed a hole beneath the engine data plate on the top of the engine case. A piece of connecting rod and connecting rod bolt was found on the left side baffling. The number three and four connecting rods were fractured and separated from their journals. The number four connecting rod, rod bearing, and journal exhibited thermal discoloration consistent with oil starvation. The oil sump contained debris, including fragments of the number three connecting rod and number four rod bearing. The crankcase had fractured, and a section containing two mounting bolts for the oil sump screen separated; the screen was clean and open. The oil pump showed rotational scoring, while the scavenge pump was unremarkable. The governor screen was clean, and the oil filter contained shiny metallic debris. Spark plugs were removed; all center electrodes were elliptical and clean except the number four bottom plug, which was wet and contained debris. The electrodes were gray, indicating normal operation. Both magnetos produced spark at all posts when tested.
Turbocharger Examination
Left Turbocharger: The compressor and turbine blades rotated freely. The compressor blades were not discolored. Internal lubrication passages showed no anomalies. The center housing exhibited moderate coking. Piston rings on the turbine wheel were present and in good condition. The turbine bearing showed scoring on the outer diameter and contact damage, and the oil chamfer hole was missing. The turbine housing had excessive exhaust deposits. The turbocharger was determined to be functional.
Right Turbocharger: The compressor vanes wobbled on the shaft and were not discolored. The compressor housing had rub marks. The compressor blades were smeared due to contact with the housing, consistent with direction of rotation. The turbine housing was white externally with exhaust residue buildup internally. The turbine wheel head was missing, and no significant rub or contact damage was noted on the turbine wheel housing or heat shield. The piston ring remained in place in the center housing seal bore. The turbine wheel head separated at the outboard edge of the piston ring groove and was not located. The shaft fractured circumferentially at a piston ring groove; the fracture surface was smeared, preventing determination of fracture type. The turbine wheel assembly's time in service could not be determined. The compressor impeller and housing showed damage consistent with rotational contact. The bearings' oil holes contained displaced bearing material, and both turbine and compressor bearings were worn. The bearing housing lubrication passages were clear. The turbine wheel piston rings were present and worn.
Maintenance History
On July 21, 2016, at a total time of 651.9 hours, the right turbocharger was removed and replaced with an overhauled unit. The last engine maintenance was a 50-hour inspection on May 18, 2017, at 771.9 hours. The flight meter at the time of the accident read 783.8 hours. Review of a work order dated July 19, 2016, revealed that the turbine wheel assembly was marked as serviceable without documentation of any inspection. The Turbocharger Overhaul Manual required removal of the turbine wheel assembly from the center housing and rotating assembly, as well as penetrant inspection, but these steps were not documented.