The US Air Force believes a software reprogramming could solve some deficiencies discovered earlier this year on the Boeing KC-46 tanker, following initial findings from testing earlier this month.
Though testing is ongoing, early data indicates that reprogramming could fix a high-frequency transmit and an “uncommanded boom extension” on KC-46, Gen Carlton Everhart, commander of the USAF Air Mobility Command, said last week.
During aerial refueling, HF transmitting must be turned off to avoid electrical sparking between the boom and receiver. The air force discovered the problem in 2016 but needed additional test data to confirm that when transmitting is turned off, it stays off. Recent tests have shown Boeing can maintain the same radio on KC-46, leaving room for a software fix.
“The vendors have come back and they believe the HF radio is within tolerance,” Everhart says. “So if it is then where do we stand as far as this inhibit switch. That still has to be tested, but they’re getting closer to that solution and they’re analyzing that data.”
While the “uncommanded boom extension” is closely related to another boom scraping problem on the tanker, Everhart noted the abnormality does not damage the aircraft. During ground testing, fuel flowed through boom, exerting pressure which pushed the boom forward and extended the boom into a test stand acting as a receptacle. The issue also occurs on the legacy fleet, where if a pilot somehow disconnects unexpectedly then the boom operator retracts the boom from the aircraft.
The USAF is collecting data on the boom issue and will pass it over to Boeing for assessment. A software modification could fix the push on the receptacle, Everhart says. The service does not yet have a schedule for when a solution will be implemented.
Meanwhile, the USAF has not begun aerial refueling tests on stealthy aircraft with the KC-46. That’s not due to the boom scraping issue, but rather the service is following its planned receiver aircraft schedule while comparing scraping frequency on the KC-46 with legacy tankers.
“It just so happens that we’ve got other airframes that we have to test first before we go into the fifth-generation aircraft,” he says.