The attending mechanic describes the probable sequence of events for this Cessna 210’s engine.

“The number two connecting rod failed, breaking the crankcase and knocking the left magneto from its mount.

The rod showed friction welding to the crank prior to failure. The counterweight was also damaged by impact with the rod. It appears the engine continued to operate briefly following the rod’s seizure. The pilot accomplished a successful landing in a soybean field, sustaining no apparent damage to the airframe. This engine had 1074 hours since major overhaul. It has a history of cylinders being removed for top overhaul, with four of them having been changed twice. The owner indicated he had been experiencing persistent over-boosting, and (this problem) had been addressed by a couple of different mechanics and shops. The turbo controller had been replaced, and subsequent to that, the waste gate had been removed, serviced, and reinstalled. Upon completion of this work, it appeared the over-boost problem had mitigated. Shortly (later) however, the engine failed. The pilot indicated engine failure was preceded by fluctuating oil pressure, loss of boost pressure, and rough operation. It is my opinion the persistent over-boosting hammered the rod bearings to the point that they were marginal by the time the boost problem was corrected. Things seemed normal until oil pressure loss through the rod bearings resulted in inadequate wastegate operation (loss of boost) and lubrication.”

Part Total Time: not given.