On April 1, 2012, about 1515 central daylight time, a Cessna U206B airplane, N3830G, experienced a loss of engine power shortly after departure from the Winterset Municipal Airport (3Y3), Winterset, Iowa. The commercial rated pilot and six passengers were not injured and the airplane sustained substantial damage. The airplane was registered to and operated by Des Moines Skydivers, LLC, Des Moines, Iowa under the provision of 14 Code of Federal Regulation Part 91 as a parachute jump flight. Day visual meteorological conditions prevailed and the airplane was not on a flight plan.

The pilot reported that he departed the airport on a jump flight and turned crosswind, and headed north. When the airplane was about 1,000 feet above ground level, the airplane seemed to stop climbing, so he looked at the engine gauges and everything seemed normal. However, as he turned back to the engine analyzer, the analyzer was flashing “CHT” and the cylinder temperature read 454 degrees F. The pilot then pitched the airplane’s nose down to cool the engine, and turned back towards the airfield. The pilot heard a muffled “thud” sound and white smoke poured from the engine. The pilot pulled the mixture control, turned the ignition and master switches off. He then yelled for the jumpers to get out, and four of the parachutists were able to exit the airplane. He performed a forced landing in a plowed field and the airplane came to stop near a dirt berm.

The responding Federal Aviation Administration (FAA) inspector reported that the airplane sustained extensive firewall damage, when the nose landing gear was torn from the airplane during the forced landing. The inspector also noted that there was a hole in the engine’s crankcase near the number four cylinder.

The engine was removed from the airframe and sent to Continental Motor’s engine test facility, in Mobile, Alabama. The engine was examined under the supervision of the NTSB Investigator in Charge, and technical representatives from Continental Motors.

A visual exam of the engine confirmed the hole in the crankcase near the number four cylinder; the engine was then disassembled. Various pieces of metal, including part of a “quick oil drain plug” was found in the engine oil sump. The number four connecting rod journal appeared distorted and had displayed extensive heat signatures. The crankshaft journals on either side of the number four rod journals did not appear distorted nor contain the same heat signatures and were coated with engine oil. The rod and crankshaft bearings appeared scored. The crankcase and crankshaft oil galleys appeared open. A reason for the loss of engine oil to the journal was not found.

A review of the engine maintenance log book revealed that the engine had approximately 3,233 total hours and about 1,730 hours since major overhaul.

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