Date: 201301
Local time of day: 1201-1800
Location: ZZZ.Airport, US
Flight conditions: Mixed
Weather elements / visibility: 50
Light: Daylight
Aircraft: Cessna 340/340A
Operator: Corporate
Operating under: Part 91
Flight plan: IFR
Mission: Passenger
Flight phase: Descent
ATC / advisory: Center ZZZ
Aircraft component: Cylinder Head
Component problem: Failed
Reporter organization: Corporate
Reporter function: Pilot Flying; Single Pilot
Reporter qualification: Flight Crew Multiengine; Flight Crew Flight Instructor; Flight Crew Instrument; Flight Crew Commercial
Anomaly: Aircraft Equipment Problem Critical; Deviation - Altitude Excursion From Assigned Altitude; Deviation / Discrepancy - Procedural Clearance; Deviation / Discrepancy - Procedural Published Material / Policy
Detector: Person Flight Crew
When detected: In-flight
Result: Air Traffic Control Provided Assistance; Aircraft Aircraft Damaged; Flight Crew Landed in Emergency Condition; Flight Crew Overcame Equipment Problem; Flight Crew Inflight Shutdown; General Declared Emergency
Contributing factors: Aircraft
Primary problem: Aircraft

Narrative: I was descending on an IFR flight plan to 4;000 FT MSL while enroute to destination. Approaching 4;000 FT MSL; the left engine made a very loud sound and shook pretty violently. I immediately began to diagnose the problem by turning the emergency fuel pump to high; which helped the engine run smoother; but did not fix the problem. During this I informed ATC that I was having issues with the left engine; but did not need any assistance at the time. I continued to test the fuel pump and monitor the engine gauges; all of which appeared normal. I requested direct to destination because they had vectored me slightly to the north for traffic. They allowed this and told me to descend to 3;000 FT MSL and contact Approach Control. I contacted Approach and let them know of my situation; and within a minute or so of contacting them I made the decision to shut down the left engine and feather it because it wasn't getting any better. I believe that it was about 3-5 minutes between the first noise and when I actually began to shut the engine down. Since I shut the engine down; I let ATC know and then had to declare and emergency. They were great and I really didn't need any extra help from them. The airplane was maintaining altitude well and the engine feathered just fine. I flew the rest of the way single engine and landed; and when I was able taxied off the runway and had a tug pull me the rest of the way in. After landing; I called Clearance and informed them I was down and just fine; and they closed my flight plan. The only real deviation that occurred during the emergency was that I deviated from 4;000 FT MSL by about 200 FT high for maybe 20-30 seconds and the descent down to 3;000 FT MSL was very slow. After I got pulled in the hanger the mechanic pulled off the cowl and discovered that my number two cylinder on the left engine had split straight in half; luckily above the piston so the piston remained seated.




Synopsis: Cessna 340 pilot shutdown the left engine in-flight after a loud sound was hear followed by violent shaking. Post flight revealed the number two cylinder was split in half.