Stability issues?……
https://www.defensenews.com/air/2021...-deficiencies/
More cost overruns are coming for Boeing as the KC-46 program logs another two technical deficiencies
WASHINGTON — Boeing will have to pay to fix two new technical problems afflicting the
KC-46 refueling tanker, which the U.S. Air Force has designated as “category 1” deficiencies that rank among the program’s most critical issues.
The Air Force has discovered that drain tubes in the KC-46′s air refueling receptacle — which are used to remove water from the aircraft — can become cracked when the tanker operates in cold temperatures, the service stated in response to questions from Defense News. According to the service, this issue has occurred approximately three times, when water in the tubes froze and expanded, forming cracks.
The second problem involves a software bug in the KC-46′s Flight Management System, which has triggered “navigation anomalies,” according to Boeing.
The Air Force said this issue has been limited to “isolated incidents,” most recently during a March 3 flight over the Pacific Ocean. Then, the crew “deferred to other navigation methods and did not declare an in-flight emergency” before landing safely in Honolulu, the service said.
Boeing added that the problem did not make the aircraft less safe and that each KC-46 has since been cleared for flight.…..
As a short term strategy for dealing with the cracked aerial refueling receptacle tube issue, Boeing has issued inspection guidance to the Air Force to mitigate known risk factors. To permanently fix the problem, however, it will have to redesign the drain line tubes and retrofit existing KC-46s with the modification, the service said.
General Electric — Boeing’s subcontractor for the Flight Management System — is already testing a software fix aimed at resolving stability problems.
To mitigate current risks, Boeing has issued guidance to help KC-46 crews to reset the system if a problem is experienced during flight. It has also delivered updated pre-flight procedures aimed at decreasing the likelihood of a software anomaly, the Air Force said.
The Air Force classified the two new problems as “category 1” deficiencies in May 2021.
Four other CAT-1 problems remain on the books: two issues with the
Remote Vision System —the camera and sensor suite that provides imagery of the receiver aircraft to boom operators during a refueling — which requires Boeing to redesign the system; a problem with
the stiffness of the boom that prevents some aircraft from being able to receive fuel; and an issue with
fuel leaks.……