Narrative:

While in cruise flight on an IFR flight plan for a weekend of flight training; I was being vectored toward my intended destination. The engine began to knock loudly and the cockpit filled with the smell of burning oil. There was no smoke. There appeared to be a power loss also; but since I reduced power immediately; I cannot be certain. After reducing power; the knocking continued. I declared an emergency and asked for vectors to the closest airport with a 3000 ft runway. I was advised that an airport was nearby and had equipment. Using the 'nearest' function on my GPS; however; I determined that a different airport was also nearby. Although the ceiling was broken at my altitude; I was able to see the second airport but not the first so I advised the controller I intended to perform a straight in landing at airport I could see; which was approximately seven miles from my position. The controller acknowledged and provided the CTAF frequency. I advised the controller I was going to go off center frequency to announce on the CTAF and land. After announcing my intentions on the CTAF; I learned another aircraft was in the pattern. This aircraft acknowledged and cut off its approach. My landing was uneventful. While taxiing to parking; the engine quit. I tried to raise my controller from the ground to advise that I had landed safely but the reception was poor. I therefore telephoned FSS to advise that I was on the ground and to close my flight plan. As it happened; the pilot of the other plane in the pattern was an airline pilot and a mechanic. He offered to look at my aircraft and after an examination was able to determine that one of the cylinders had cracked. He was of the opinion that if I had not landed promptly the engine would have been destroyed.

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Original NASA ASRS Text

Title: A BE35 Pilot reported engine failure in cruise flight. He declared an emergency and diverted to the nearest suitable airport.

Narrative: While in cruise flight on an IFR flight plan for a weekend of flight training; I was being vectored toward my intended destination. The engine began to knock loudly and the cockpit filled with the smell of burning oil. There was no smoke. There appeared to be a power loss also; but since I reduced power immediately; I cannot be certain. After reducing power; the knocking continued. I declared an emergency and asked for vectors to the closest airport with a 3000 FT runway. I was advised that an airport was nearby and had equipment. Using the 'Nearest' function on my GPS; however; I determined that a different airport was also nearby. Although the ceiling was broken at my altitude; I was able to see the second airport but not the first so I advised the controller I intended to perform a straight in landing at airport I could see; which was approximately seven miles from my position. The controller acknowledged and provided the CTAF frequency. I advised the controller I was going to go off center frequency to announce on the CTAF and land. After announcing my intentions on the CTAF; I learned another aircraft was in the pattern. This aircraft acknowledged and cut off its approach. My landing was uneventful. While taxiing to parking; the engine quit. I tried to raise my controller from the ground to advise that I had landed safely but the reception was poor. I therefore telephoned FSS to advise that I was on the ground and to close my flight plan. As it happened; the pilot of the other plane in the pattern was an airline pilot and a mechanic. He offered to look at my aircraft and after an examination was able to determine that one of the cylinders had cracked. He was of the opinion that if I had not landed promptly the engine would have been destroyed.

Data retrieved from NASA's ASRS site as of April 2012 and automatically converted to unabbreviated mixed upper/lowercase text. This report is for informational purposes with no guarantee of accuracy. See NASA's ASRS site for official report.