Date: 201408
Local time of day: 1201-1800
Location: ZZZ.ARTCC, US
Flight conditions: VMC
Weather elements / visibility: 10
Light: Daylight
Aircraft: Piper Twin Piston Undifferentiated or Other Model
Operator: Personal
Operating under: Part 91
Flight plan: IFR
Mission: Personal
Flight phase: Cruise
Airspace: Class G ZZZ
ATC / advisory: Center ZZZ
Aircraft component: Cylinder Head
Component problem: Failed
Reporter organization: Personal
Reporter function: Single Pilot; Pilot Flying
Reporter qualification: Flight Crew Instrument; Flight Crew Multiengine; Flight Crew Private
Human factors: Situational Awareness; Troubleshooting; Distraction; Workload
Anomaly: Aircraft Equipment Problem Critical; Deviation / Discrepancy - Procedural Other / Unknown
Detector: Person Flight Crew
When detected: In-flight
Result: Aircraft Aircraft Damaged; Flight Crew Landed in Emergency Condition; Flight Crew Took Evasive Action; Flight Crew Inflight Shutdown; Flight Crew FLC complied w / Automation / Advisory; Flight Crew Diverted; General Declared Emergency; General Maintenance Action
Contributing factors: Aircraft
Primary problem: Aircraft

Narrative: While in cruise enroute; a sudden vibration in the airplane became quite severe in the left engine nacelle. This was quickly followed by a hole in the outboard cowling of left engine. The engine still producing power was shut down in the usual way; feathered; and fuel cut off. The propeller feathered as it should. ATC was immediately notified. I am not sure at that point that I used the word emergency; I know I didn't say Mayday. I was unable to hold my assigned altitude at that point. Advising ATC of my situation; I asked for location of nearest airport. The controller was most helpful in advising me in bearing and distance to a nearby airport. I turned in that direction and continued to control the airplane in the usual single-engine fashion. I was in radar contact throughout this; I just don't know if I actually declared an emergency. I know I was dealing with a very urgent situation. The controller asked regarding number of souls and fuel on board.The flight continued to circle over the airport as I lost altitude under control and landed. I talked with the controller until switching over to advisory frequency. He was throughout the ordeal most helpful; courteous; and professional. After landing I contacted flight service on a land line and asked them to relay my safe arrival to Center. There were no physical injuries to myself or my wife.Upon landing; I taxied to the ramp and shut down the other engine. Exiting the airplane I found the right tire flat. I had not realized that on taxiing; I suspect due to the unusual yaw and drag from the asymmetric thrust of the right engine.At that point; the plane was found to be otherwise undamaged except for the damaged cowling over the left engine which had two holes in it. The lower outboard hole was 8 inches long. Removal of the cowling revealed that the Number 4 cylinder head had completely separated from the crankcase at the junction of the cylinder barrel and the flange. The piston was completely destroyed and the connecting rod was badly distorted. Oil was streaked down the outboard edge of the cowling.I think any deviation from assigned altitudes and headings were necessary to deal with an emergency situation; but I am filing this also as I am quite concerned as to what could have caused such a catastrophic failure of a cylinder head in cruise flight. I wouldn't want anyone else to have this kind of 'stress' if it could be avoided. The engine only had approximately 250 hrs on the heads.




Synopsis: A PA-39 engine with 250 hours on the heads suffered a catastrophic cylinder failure when one separated from the crankcase in flight. An emergency was declared; the engine shutdown and a safe landing followed at a nearby airport.