Boeing will have to fix two more Category I deficiencies in the US Air Force’s new KC-46 aerial tanker, increasing its price.

The issues, both of which are going to be addressed at Boeing’s expense, involve receptacle drain line tubes and Flight Management System software.

The problems were discovered in March 2021 in what the United State Air Force called “isolated incidents” and did not result in any emergencies. 

“There are no operational restrictions on fielded KC-46s due to either of these deficiencies nor do they affect [the] plan for KC-46 Interim Capability Release,” USAF spokesperson Joshua Benedetti said in a statement.

Benedetti also confirmed that Boeing will address both deficiencies at its own expense, as per the fixed-price contract. According to that contract, any expenses that exceed the initial $4.9 billion price have to be covered by Boeing. 

In January 2021, the overruns have already exceeded $5 billion, overtaking the initial contract cost. Previous critical deficiencies included fuel leaks, unsecure cargo fasteners, and refueling booms incompatible with some aircraft, not including hundreds of Category II deficiencies.

Despite long-running problems, USAF has expanded the initial KC-46 order several times since the resumption of its deliveries. The current plan totals 179 aircraft, of which 46 have been delivered.