CHI96LA060

The pilot reported an engine power surge, followed by a loud bang from the engine area, and a total loss of engine power. A piece of the snap ring from the turbocharger was found jammed between the oil scavenge pump gears and the oil scavenge pump case. This caused the oil pump to fail, resulting in no oil pressure and a total loss of engine power. The center section of the turbocharger had been rebuilt using automotive parts. The airplane's propeller, fuselage bulkheads and lower fuselage skin were bent during the emergency landing.

On December 20, 1995, at 2030 eastern standard time (est), a Cessna T210N, N5083C, piloted by a commercial pilot, sustained substantial damage during an off airport landing. The pilot reported a total loss of power shortly after takeoff, from the Indianapolis International Airport. Visual meteorological conditions prevailed at the time of the accident. The 14 CFR Part 135 flight was operating on a IFR flight plan. The pilot reported no injuries. The flight departed from Indianapolis, Indiana, en route to Chicago, Illinois, exact time unknown.

The pilot was interviewed by telephone by the investigator in charge (IIC) on December 20, 1995. The pilot stated that after the first power reduction following takeoff, the engine seemed to surge, and then continued to operate normally. The pilot reported that three to four minutes after the first power reduction the engine began losing power. The pilot reported hearing a loud bang from the engine area, followed by a total loss of engine power. The pilot remembered seeing zero revolutions per minute on the tachometer, even though the propeller was still windmilling. After the total loss of power the pilot made an emergency landing in a snow covered field, with the landing gear retracted.

Post flight examination of the airplane's engine revealed the following. External damage to the crankcase was seen above the number 5 cylinder's connecting rod. The oil pump drive shaft failed where the splines attach to the accessory gear. The number 5 cylinder's connecting rod was separated from the crankshaft. Two other connecting rods showed evidence similar to lack of lubrication. A piece of snap ring was found jammed between the oil scavenge pump gears and the oil scavenge pump case. The oil scavenge line runs from the turbocharger to the oil scavenge pump on this engine.

The turbocharger should contain four snap rings, one snap ring was missing. The shaft on the turbocharger had approximately one quarter inch of end play. The maximum design limit is .005 inches. The compressor and turbine blades on the turbocharger were damaged due to rubbing. A portion of one compressor blade was missing. The turbocharger center section uses two roll pins internally. These roll pins were found sheared when the turbo charger was disassembled. The roll pins appeared to be spiral roll pins. Automotive roll pins use a spiral design. The center section measured approximately .010 inches oversize, where one bearing installs. Automotive turbocharger's of this design are allowed to oversize this area by .010 inches, aircraft turbocharger's are not allowed to oversize this area. A portion of the bearing area in the center section of the turbocharger had fractured, and broken loose. Aircraft turbocharger center sections of this design are made of ductile iron. This unit was made of cast iron as analyzed by the National Transportation Safety Boards Materials Laboratory Division, in Washington, DC.

The last documented overhaul of the turbocharger was on December 13, 1988. From December 13, 1988, until the day of the accident, the aircraft had accumulated 1,181 hours.

The airplane's propeller, fuselage bulkheads and lower fuselage skin were bent during the emergency landing.