By Doug Cameron Boeing Co. said its work on replacing the Air Force One presidential jets is behind schedule, taking another charge on the loss-making program that has added to the financial pressures from the stuttering recovery of its commercial airliner business. The aerospace giant is contracted to deliver two converted 747-8 jumbo jets by the end of 2024, but has been forced to switch suppliers for some of the interior work on the planes. It took a $318 million pretax charge on the project in the latest quarter, the second in a year and the latest drag from a defense unit that it is relying on to carry it through to a recovery in commercial airline traffic.