Damage was found on an engine cylinder of the Long Island-based vintage warplane that crashed last month into the Hudson River off New Jersey, killing an experienced pilot, federal investigators said in a preliminary report.

The National Transportation Safety Board said the finding is consistent with an “in-flight occurrence” that forced pilot Bill Gordon to make a distress call to the Newark air traffic control tower during a three-plane photo shoot on May 27.

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The June 15 report does not point to what may have damaged one of the 18 cylinders on the Pratt and Whitney R-2800 radial engine. The probe is ongoing and a fuller report could take up to a year.

Oil was also found on the exterior of the engine, the report said. The plane’s airframe was generally intact, the NTSB said.

The 1944 P-47 Thunderbolt, part of the American Airpower Museum in Farmingdale, left Republic Airport at 7 p.m. and went down about 30 minutes later during a shoot to publicize the museum and the plane’s scheduled performance at the Bethpage Air Show during the Memorial Day weekend. A museum spokesman had said the pilot reported an engine failure.

The plane’s owner, Jeff Clyman, said he could not comment on the preliminary findings because he is a party to the NTSB investigation.

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The Pratt and Whitney R-2800 was this country’s first 18-cylinder radial engine and was considered the most powerful engine at the time. It was the engine for several bombers and fighters at the time, and according to the website World War Wings, many war-era airshow aircraft still fly with the original R-2800 engines.