NTSB Identification: NYC02LA169.
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Accident occurred Saturday, August 17, 2002 in Guilford, CT
Probable Cause Approval Date: 09/01/2004
Aircraft: Bellanca 8GCBC, registration: N86714
Injuries: 1 Uninjured.

NTSB investigators may not have traveled in support of this investigation and used data provided by various sources to prepare this aircraft accident report.

At 1,300 feet, while towing a banner, the airplane's engine experienced severe vibrations and a loss of power. The pilot located a field where he could safely drop the banner, and descended to 500 feet to make the drop. After the drop, the airplane would not climb, and the vibrations increased, so the pilot decided to land in the field while he still had control of the airplane. During the approach, the pilot had to clear trees, and "came in a little high and fast." After touching down on a grassy field, he "tapped the toe brakes," and the airplane nosed over. A post-flight examination of the engine revealed that the number 3 cylinder was cracked and its exhaust valve seized. Further examination revealed a continuous fracture around the head, in the vicinity of the fourth and fifth cooling fins, with a surface consistent with fatigue cracking. The cylinder barrel had been remanufactured, then joined to a new cylinder head. Threads 1, 2 and 3 of the cylinder barrel displayed protruding material that matched corresponding thread indentations in the cylinder head. There was no evidence of material defect or dimensional anomaly from manufacturing processes. There was also no evidence as to the specific nature or extent of possible crack initiation forces. According to logbook information, the cylinder was installed in 1999, and had approximately 635 hours of service. Two accident investigations involving similar issues are CHI01FA329 and NYC02FA178.

The National Transportation Safety Board determines the probable cause(s) of this accident to be:

Fatigue cracking of the number 3 cylinder head. A factor was the presence of protruding material on the cylinder barrel.

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