The KC-46 Pegasus tanker program has been a bewildering boondoggle. Now the Air Force says it will be years before it is fully operational as a host of critical design deficiencies continue to plague the program. Testing showed that some of these issues can have adverse impacts on the thirsty aircraft refueling from the KC-46. These include battering the receiving aircraft itself and scraping its skin with the boom. Although we don’t know when the video below was shot or the exact situation surrounding beyond that the aircraft shown is a test F-15E, it depicts a tense incident in which a KC-46 boom appears to slip off the Strike Eagle’s refueling receptacle, with its control surfaces nearly banging into the fighter’s canopy.
At the heart of the KC-46 design are the boom and Remote Vision System. The latter of which has boom operators wearing 3D glasses and sitting in front of screens at stations in the front of the 767 derivative to control refueling operations (read all about it here). Both of these key components, the boom and the Remote Vision System, do not meet the USAF’s expectations and are being redesigned. This is occurring as the jets continue to be delivered.
The video above may depict one continuing issue the KC-46 has with requiring more force to connect with the receiving aircraft than its predecessors, which can cause impacts of the boom on the receiving aircraft.
Flightglobal.com explained the issue as such:
Boeing is redesigning the actuator to address hardware specification flaws coming from the service’s initial design requirements. Designing and retrofitting the aircraft will likely cost more than $300 million, according to a Government Accountability Office (GAO) report released in June 2019. Programme officials told GAO that developing a solution, and receiving Federal Aviation Administration certification, would likely take three to four years.
The boom’s issues became apparent during developmental flight testing, when pilots of lighter receiver aircraft – such as Fairchild Republic A-10s and Lockheed Martin F-16s – reported they needed more force to connect and disconnect their aircraft from the boom, as compared to older tankers, like the KC-135 and KC-10, says GAO.
The additional force required can cause the receiving aircraft to suddenly lunge and collide with the boom, damaging the aircraft’s glass cockpit canopy or tail. It can also damage the boom.
You can read more about the KC-46 boom’s woes with ‘thrust resistance’ in this past piece of ours. At the same time, it’s important to remember that aerial refueling is hard and incidents happen regardless of the platform, especially in testing when flaws are usually identified. The fact some of those highly critical flaws are not remediated even as the KC-46s are being delivered, and won’t be in the near future, is the major issue.
On a positive note, the KC-46 can begin carrying passengers and cargo again. These important missions were restricted for months due to the discovery that the floor latches that keep cargo locked in place were inadvertently releasing. A major shift in cargo could send the plane careening out of control or it could injure or kill passengers flying in the cabin. A fix is now being retrofitted to the budding fleet that the Air Force is satisfied with. Also, on December 22nd, 2019, a KC-46 made the type’s first around the world flight.
All this is well and good, but the jet’s primary mission is refueling a wide array of aircraft in flight. As it sits now, its ability to do that to the standards the USAF requires is still very much a work in progress.
UPDATE:
Boeing has informed us that the boom did not make contact with the canopy of the Strike Eagle and they gave us some additional info about the test depicted in the video clip:
No part of the air refueling boom ever hit the fighter’s canopy, nor did it “slip off.” The operator views the image in 3-D. The video in your article is 2-D, so there is no depth to the image. The KC-46 boom operator initiated a disconnect and the boom operator flew the boom clear of the receiver with a minor contact in the area around the receptacle. This happened during a procedure called “Contact/Disconnect Testing.” Incidental contacts that occur during testing are not unusual, as seen on disconnect here. This is why we test.
This event had no effect on the certification of the KC-46A and F-15E. This was simply a valuable test condition that helped determine the compatibility of the tanker/receiver pair. F-15E was cleared as a receiver on October 30th, 2019.
Another source noted that this was a corner of the envelope point that is unlikely to occur in the future during normal operations. The test is meant to go beyond the normal operational limits of the refueling hardware and sometimes unique occurrences are found, as is shown in the video.
Author’s note: the headline and a few areas of the text were tweaked to better reflect this new information.
Contact the author: Tyler@thedrive.com