Results of tests conducted in 2018 showed the boom was problematic when the company tried to test full functionality of the boom system during refueling of A-10, C-17, and F-16 receivers.
The development of the KC-46’s refueling boom wasn’t effectively overseen by the US Air Force (USAF), leading to additional delays and costs and a lingering deficiency that prevents the tanker from refueling some USAF aircraft, according to a new Pentagon watchdog report.
According to a report released by the Defense Department Inspector General on May 27, 2021 following a redesign of the refueling boom in 2012 the service’s KC-46 Program Office didn’t effectively manage the development of the system. As reported by Air Force Magazine, that year, Boeing presented a system design during the preliminary design review that “differed significantly” from the initial design from the 2011 contract award.
Despite the new design, the Air Force did not “ensure that critical technologies for the refueling boom were demonstrated in a relevant testing environment,” and it “did not verify full functionality” of the boom in accordance with the program’s own plan when performing flight tests, the IG found.
The Program Office didn’t revalidate changes to critical technologies “at any point during the engineering and manufacturing development phase, since revalidations were not required by DOD policy,” the report states. Officials believed, since the KC-46’s boom is based on the proven system on the KC-10, further assessment of boom technologies was not necessary.
“Despite encountering flight test failures in January 2016 that required Boeing engineers to redesign the refueling boom, the KC-46 Program Office officials did not change their decision to perform reduced flight testing. This reduced flight testing did not include the stressing conditions under which the refueling boom problem could potentially occur.
Because of this, results of tests conducted in 2018 showed the boom was problematic when the company tried to test full functionality of the boom system during refueling of A-10, C-17, and F-16 receivers. According to the DOD IG, the KC-46 still can’t refuel the A-10 and some variants of the C-130, with operational limits on several other airframes.
These problems led to August 2019 and March 2020 contract modifications at a cost of $100 million to redesign the KC-46’s refueling boom, with a retrofit not estimated to begin until January 2024.
“Had KC-46 Program Office officials effectively managed the development and testing of the refueling boom for the KC-46A tanker, the Air Force would not have had to spend an additional $100 million for the redesign of the refueling boom to achieve its required performance,” the IG’s report states.
As explained by Defense News, currently the KC-46 has four remaining category 1 deficiencies [which indicate problems that impact operations or pose a safety risk]: two involving the Remote Vision System that are expected to be resolved when a new version of the system is rolled out in 2023; a problem with the stiffness of the air refueling boom that keeps it from being able to refuel some of the planes in the service’s inventory; and an issue with fuel leaks.
The aircraft has been in development since Feb. 24, 2011, and its initial flight occurred in Dec. 2014. The current contract, with options, provides Air Mobility Command an inventory of 179 KC-46A tankers. The first KC-46A was delivered to McConnell Air Force Base, Kansas on Jan. 25, 2019.
The KC-46A is the first phase in recapitalizing the US Air Force’s aging tanker fleet. With greater refueling, cargo and aeromedical evacuation capabilities compared to the KC-135, the KC-46A will provide next generation aerial refueling support to Air Force, Navy, Marine Corps and partner-nation receivers.
Photo credit: U.S. Air Force via Robert Sullivan on Flickr