Accident Details
On March 2, 2016, at about 1500 central standard time, a Cessna 150G airplane, registration N3339J, was substantially damaged during a forced landing to a field near Simmesport, Louisiana. The student pilot was not injured. The instructional flight was conducted under 14 Code of Federal Regulations Part 91 in visual meteorological conditions. No flight plan had been filed. The cross-country flight departed Hammond Northshore Regional Airport (HDC) at about 1400, en route to Alexandria International Airport (AEX).
Engine Failure and Forced Landing
According to the student pilot, while cruising at 4,500 feet mean sea level, the engine lost power and deposited engine oil over the front windscreen. During the forced landing to a plowed field, the airplane nosed over, resulting in substantial damage to the fuselage.
Post-Accident Examination
The Federal Aviation Administration inspector noted a hole in the crank case directly aft of the #1 cylinder. The engine was shipped to a laboratory for examination under the auspices of the National Transportation Safety Board investigator-in-charge and with assistance from Continental Motors investigators.
The crank case was cracked in multiple locations, with a hole approximately 2.5 inches by 2.5 inches. Oily residue was present along the entire outer case and engine. Pieces of piston, piston rings, lifter, rod bolt, connecting rod, and a thrust washer were recovered from the oil sump. The #1 piston and rod assembly were jammed and frozen in the cylinder; the rod assembly was fragmented and partially separated at the rod cap. The rod bolt broke at the split line of the rod and rod cap. The #2 piston and rod assembly were also jammed and frozen. A second thrust washer fell from the assembly after cylinder removal. One thrust washer near the propeller flange on the crankshaft exhibited fretting.
Maintenance History
The front main crankshaft bearing (part #633398) with a separate thrust washer was removed. According to the most recent revision of the Continental Motors Overhaul Manual and Illustrated Parts Catalogs (both dated 2011), the front main bearing (part #627246) with an integrated thrust washer should have been used. The engine had been disassembled and stored for about two years before being reassembled in May 2015.
The mechanic who reassembled the engine stated many original components were not available for reference. He used a parts catalog dated March 1977, which indicated that all engines required a three-piece bearing and thrust washer assembly. He noted that while ordering kits, the first three were incomplete; the fourth kit contained the main bearing with the separate thrust washer.
The mechanic experienced difficulty keeping the thrust washer in place during reassembly. He contacted Continental Motors customer service and was instructed to torque the case down and install the cylinders last to secure the washer. He followed these instructions, installing the #3 cylinder last. The customer service representative did not verify the correct part number.