Cessna 340/340A
Flight Crew Instrument; Flight Crew Multiengine; Flight Crew Air Transport Pilot (ATP)
Flight Crew Last 90 Days 130; Flight Crew Total 14500; Flight Crew Type 1200
Aircraft Equipment Problem Critical
Flight Crew Inflight Shutdown; Flight Crew Landed in Emergency Condition; General Declared Emergency
Aircraft
Left engine started running very rough for approximately 10 seconds followed by an immediate seizure. Propeller was not able to feather. [I] declared an emergency with ATC. Aircraft returned to land at [departure airport]. Emergency vehicles were dispatched. Aircraft landed normally. Aircraft taxied under own power to FBO. After quick inspection of the left engine it was evident an internal catastrophic failure had occurred with the crankcase being broken near the #2 cylinder with evidence of a broken connecting rod. Further investigation and analysis will be required for a proper cause. No other damage done to the aircraft.
C340 pilot reported that the left engine had a catastrophic internal failure and then failed to feather. Aircraft landed with no other issues after an emergency was declared.