Adams has been scrutinized as part of a wider corruption probe.
Scrutiny of the flights is part of a wider corruption investigation involving a top Turkish Airlines executive, aides to the mayor and Adams, who previously had his phones and other electronic devices seized.
Sources have said at least part of the investigation involves whether donations from Turkey were traded for political favors, including possible pressure exerted on the New York Fire Department after a delay with the operating certificate of the new Turkish consulate.
A spokesman for the U.S. Attorney’s Office for the Southern District of New York declined to comment.