(Adds detail on KC-46 program delays)
March 7 (Reuters) - The U.S. Air Force said the first delivery of KC-46 aerial refueling tankers from Boeing Co , scheduled for the second quarter of 2018, is more likely to occur late in the year.
"This assessment is based on known risks and predicted impacts associated with airworthiness certifications and slower than expected flight test execution," the Air Force said in a statement on Tuesday.
These potential delays will not result in additional program cost to the taxpayer, the statement said.
Boeing could not be immediately reached for comment.
The world's biggest maker of jetliners is expected to deliver 18 tankers.
In the third quarter of 2017 the company took a $329 million charge for its KC-46 aerial refueling tanker program in its quarterly results, hurting profit. Charges related to the program have reduced profit by $1.9 billion after tax. (Reporting by Ismail Shakil in Bengaluru and Chris Sanders in Washington; editing by Susan Thomas and Grant McCool)