AIR International outlines the KC-46A Pegasus aerial refuelling tanker, America’s new air mobility workhorse, and the challenges remaining for the programme
In ancient Greek mythology a Pegasus is a mythical winged divine horse. In modern America, a Pegasus is a Boeing 767 with a few clunky subset designators, dubbed the KC-46A. It’s the brand new all-American aerial refueller that’s set to replace the god father of tankers, the majestic, 1950s era KC-135 Stratotanker. But its development and service introduction with the US Air Force has been an ugly tale of ‘big deal’ problems and a multi-billion-dollar cost tag for Boeing, which marketed the aircraft as a low-risk solution for the US Air Force’s new tanker requirement. There can be little doubt that if the Air Force had been permitted to stick with its original selection for the KC-X programme, the A330-based KC-45, new tankers would be operational in combat zones right now.
Initial deliveries
On January 25, 2019, the US Air Force KC-46A tanker programme delivered the first two KC-46As to the 22nd Air Refueling Wing at McConnell Air Force Base, Kansas. Aircraft, serial numbers serial numbers 15- 46009 and 17-46031, departed Everett Paine Field on their delivery flight to McConnell; a notable milestone for the programme.
The US Air Force posture statement for FY2020 released by the Secretary of the Air Force said: “Our aerial refuelling capability underwrites the global nature of Air Force power and enables the rapid deployment of aircraft. We recently welcomed our first KC- 46 tankers and are proposing to buy 12 more KC-46 tankers in Fiscal Year 2020.”
Colonel Rich Tanner, 22nd Air Refueling Wing commander, told AIR International: “As of October 2019 we are up to 15 airplanes. Our Airmen have worked diligently since [first] delivery to generate the sorties and fly the missions required for IOT&E and beyond. Along the way we’ve learned a lot and our hands-on work helps the Air Force and the manufacturer address the concerns from operator and maintainer perspectives.”
The second unit to receive the KC-46 was the 97th Air Mobility Wing based at Altus Air Force Base, Oklahoma; the KC-46 school house. AIR International received an update concerning operations at Altus from Colonel Matthew Leard, the 97th Air Mobility Wing commander: “The 97th received its first KC- 46A Pegasus on February 8, 2019, and is now [October 2019] home to five KC-46s. Here at mobility’s hometown, we have a long history of training our nation’s airlift and air refuelling crews and we will remain the first stop in training KC-46 pilots and boom operators. Like every new advanced weapon system, we are working through the challenges of building up its combat capacity, but we are 100% confident it will bring the right suite of capabilities to any future fight.”
On hold, off hold
However, after delivery of six new KC-46As the Defense Contract Management Agency (DCMA) halted any further deliveries on February 20, 2019 because foreign object debris was found at various locations inside the brand new aircraft; a critical issue for any aircraft. According to a March 1 report in the Seattle Times, the debris included loose tools and pieces of debris. At the time Air Force spokeswoman Major Malinda Singleton said the Air Force would not accept deliveries of the tanker until the production aircraft were cleared, and the service and DCMA had approved a corrective action plan by Boeing designed to prevent FOD in the future. A memo issued by Boeing’s factory managers, obtained by the Seattle Times, stated that eight tools were found in aircraft delivered to the Military Delivery Center at Everett Paine Field, which declared a Level 3 alert on the assembly line, one level from mandatory factory shutdown.
Following an out brief of the Defense Contract Management Agency-approved corrective action plan to the Air Force service acquisition executive and Commander, Air Mobility Command, Boeing delivered the seventh KC-46 to Altus on March 11 following a new closely scrutinized acceptance process.
With lives and billions of dollars on the line, Boeing declared a FOD amnesty day on March 15. Defense One got to see a copy of an email issued by Gena Lovett, vice president for manufacturing, safety and quality which cited multiple foreign object debris escapes involving some of the companies most critical programs. Lovett wrote: “This includes the identification and removal of unnecessary tools, equipment, electronic files, documents and refuse. We all have a responsibility to maintain safe, clean, efficient and FOD-free working areas and it’s so vitally important to who we are we’re making it a company-wide priority.”
This initial plan didn’t do the intended job because on March 23 the Defense Contract Management Agency halted KC-46A deliveries for a second time. Once again because foreign object debris was found in closed compartments on a KC-46A at the Everett production facility. This led to a more stringent pre-delivery inspection process approved by Dr Will Roper, Assistant Secretary of the Air Force for Acquisition, Technology and Logistics on April 5. This process includes very close inspection scrutiny of all the aircraft’s sealed compartments for foreign object debris. Such was the concern about the closed compartment issue that KC-46A tankers already delivered to McConnell and Altus also had to be checked. Air Force personnel at both bases were tasked to drain and inspect the fuel tanks for foreign object debris.
Boeing said it is committed to delivering FOD-free aircraft to the Air Force and is conducting additional company and customer-specified inspections of the jets, and has implemented preventative action plans.
During April 2019 Congressional hearings, then Secretary of the Air Force, Heather Wilson commented: “We expect excellence in the manufacture of our aircraft, and we are working with Boeing on corrective action plans.”
In its June 12, 2019 National Defense Authorization Report for FY2020, the House Armed Services Committee expressed concerns about the progress of the KC-46A: “The committee notes that the Department of Defense Mobility Capability Requirement Study identified a tanker force structure inventory requirement of 479 aircraft. Integral to this capability is the delivery of mission capable KC-46A aircraft and the continued development of additional tanker aircraft after the expiration of the current KC-46A contract with Lot 13 in 2027.
The committee notes that the Secretary of the Air Force has completed a capability-based assessment and signed off the initial capability document for the requirements associated with the next-generation tanker, but has not started an analysis of alternatives. The committee believes the Secretary of the Air Force has several viable options to ensure future tanker capability, to include acquiring a non-developmental commercial derivative tanker while bridging from the end of the KC-46A production to the new developmental tanker. Therefore, the committee directs the Secretary of the Air Force to submit a report to the congressional defence committees…on a 30-year vision for the tanker force structure.
The report shall include the following. One, the current KC-46A tanker acquisition timeline through Lot 13. Two, future tanker production options to include an acquisition timeline comparison of a bridging non-developmental commercial derivative tanker and new tanker development. Three, modernization options for the entire tanker force structure through the 30-year vision timeline.
Deliveries resumed
Deliveries were once again resumed. On August 8 and 9, two KC-46s (serial numbers 17-46029 and 17-46034) flew to Pease Air National Guard Base, home of the New Hampshire Air National Guard’s 157th Air Refueling Wing. AIR International received an update from Colonel John Pogorek, 157th Air Refueling Wing commander: “We received the Air National Guard’s first two KC-46s in August 2019 and expect to have our full complement of 12 aircraft on-station by June 2020. Pease Air National Guard Base has undergone $100 million in construction projects to accommodate the KC-46 Pegasus. Currently, we have pilots and boom operators training with the KC-46 at Altus Air Force Base, Oklahoma and McConnell Air Force Base, Kansas. Ultimately, these activities will result in our ability to generate the sorties and fly the missions required by Air Mobility Command.”
Cat ones
The US Air Force uses a deficiency categorization protocol for all issues with a weapon system. A category 1 deficiency is classed as one which may cause death or severe injury; may cause loss or major damage to the weapon system; or critically restricts the combat readiness capabilities of the using organization.
Boeing is working to correct four Category 1 deficiencies impacting the KC-46A tanker. Two with the remote vision system used for aerial refuelling, one affecting the refuelling boom’s performance, and since September, one involving cargo restraint devices.
Remote Vision System
The Rockwell Collins remote vision system (RVS) generates and displays video feeds on the aerial refuelling operator station using a set of cameras located around the underbelly of the KC-46.
In January, US Air Force Acquisition spokesperson, Captain Hope Cronin said the Air Force was allowing deliveries to proceed but programme issues were still to be resolved.
AIR International spoke with Michael Hafer, Boeing’s Global Sales and Marketing Director for the KC-46 Program concerning the remote vision system on the KC-46. He said: “This system is a major upgrade to similar systems developed and used on Dutch KDC-10 and Japanese KC-767 tankers. The US Air Force has done extensive flight testing with the RVS, and has identified visual acuity challenges in a small percentage of the tanker flight envelope.
“More specifically, the Air Force has an issue where the KC-46 boom operator, using the RVS, may not have the visual acuity to confirm the boom made contact with the receiver aircraft during refuelling, contacts outside of the air refuelling receptacle. Boeing and the US Air Force are working on changes to hardware and software, and a test programme to achieve Air Force certification.”
Fly-by-wire boom
There are issues associated with development and operation of the new digital flying boom used for refuelling US Air Force aircraft. A June 2019 US Government Accountability Office report said the new KC-46A boom is stiff and could affect operations and cause damage to aircraft with low observability coatings.
Explaining the fault, Mike Hafer said: “The KC-46 boom is a fly-by-wire, digital aerial refuelling boom built in house by Boeing to US Air Force specifications. The Air Force has tested the new boom with 14 different types of aircraft and has so far achieved certification with seven types of aircraft. However, light weight, thrust-limited receivers, like the A-10, have challenges for remaining in contact with the boom in corners of the aerial refuelling envelope. Testing is still underway, and hardware and software changes are being evaluated to improve and finalize the boom’s air refuelling performance”.
Boeing is also working to deliver the Wing Aerial Refueling Pod System (WARPS) to the Air Force for testing; WARPS is the system used to aerial refuel probe equipped aircraft; those operated by the US Marine Corps, US Navy and many allied nations.
A Boeing spokesperson for the KC-46 program commented: “The Wing Aerial Refueling Pod System flight testing, including WARPS receiver certification for the F/A-18 Hornet is complete. The Boeing- Air Force team will perform one more flight for electromagnetic effects testing for WARPS FAA Supplemental Type Certification issuance using a production standard aircraft in January 2020. This form of flight testing is the precursor to system delivery. Boeing is working with the Air Force on the delivery plan and schedule.”
Cargo restraint devices
According to the US Air Force, during several long-range KC-46A test flights with the aircraft loaded with cargo, multiple cargo floor restraint locks malfunctioned and came unlocked. Prior to departing on each mission, aircrew fully installed, locked and thoroughly inspected each restraint, and performed routine inspections of the restraints in flight. Despite the safety measures, the unlocking occurred during flight, though no cargo or equipment moved and there was no specific risk to the aircraft or crew.
A KC-46 is cleared to carry two types of rolling pallets; one for passenger seating (up to 58) and 463L cargo pallets (up to 18) or a combination of both. Each type of pallet is fixed to the floor of the aircraft’s cargo hold with cargo restraint devices.
Explaining the problem, Mike Hafer said: “The Air Force requirement calls for the aircraft to be able to reconfigure within two hours after landing. These locking systems secure to the floor with a switch lock, but are removable. During flight testing, dynamic vibrations caused several of the mechanisms to move out of confirmed locking position. We have developed a mechanical fix to this problem. It has passed initial flight testing and we are on path to provide a permanent fix to this problem.”
During the Air Force Association’s Air, Space and Cyber conference held at National Harbor, Maryland, Commander Air Mobility Command, General Maryanne Miller told reporters: “We are eight months into accepting our airplanes, and Boeing has not presented a solution that meets all the parameters. Boeing’s solutions for the RVS just aren’t good enough.
"The cameras used to monitor the fuelling systems feed three images to the screen and Boeing has struggled to provide effective depth perception, which makes it pretty challenging to mate the boom and manage refuelling. In a couple months, that is what I’ll be looking for… we have got to get this airplane into the fight.”
Air Force and Air Mobility Command leaders met Boeing representatives at Scott Air Force Base, Illinois, Headquarters Air Mobility Command on September 30 to discuss ongoing efforts to identify viable solutions for KC-46 deficiencies.
Creating a hot mess
The US Air Force tanker fleet comprises 396 KC-135 Stratotanker aerial refuelling aircraft (with an average age of 63 years), an aircraft which have been updated several times after deliveries between 1955 and 1965. In addition, the tanker fleet includes 59 KC-10 Extenders delivered in the 1980s (with an average age of 32 years). During a much shorter service life compared to the KC-135s, KC-10s have sustained a heavy utilisation rate to the point where today, they are a challenge to maintain.
While the KC-135 fleet is old, the airframes still have service life remaining, and the Air Force operates an established programmed depot maintenance system which keeps the aircraft overhauled and updated.
A 2018 Transportation Command study supported the Air Force’s stated requirement for 479 aerial refuelling tanker aircraft.
America’s jet-powered tanker fleet is assigned to Air Mobility Command with each air refuelling squadron supporting aerial refuelling, aeromedical evacuation and personnel/cargo transportation as their primary mission assignments.
Aerial refuelling is a core element of global reach, increasing US and coalition range and capability. Air Mobility Command’s posture priorities include readiness, sustaining nuclear response, mobility operations in a contested environment, force development, modernization and innovation.
The road to KC-46 has been long, difficult and a touch perverse. In the 1990s, the Air Force considered buying and/or leasing an upgraded version of the 767 tanker from Boeing. In 2003 the project was put on hold when allegations of corruption were discovered; ultimately the contract was cancelled in 2006.
A request for proposal was released in 2007 for the KC-X programme including 179 new tankers.
Boeing proposed its KC-767 and faced off against the larger Northrop Grumman- EADS A330 Multi Role Tanker Transport. On February 29, 2008, the A330 dubbed the KC-45 was selected. Boeing was hopping mad at the decision and protested the contract award. This was sustained by the Government Accountability Office with its June 2008 decision in favour of Boeing. Bidding was reopened in July, KC-X solicitation was cancelled in September. One year later the Air Force started its process for accepting new bids. In March 2010 Northrop Grumman withdrew but EADS soldiered on. That was in vein. On February 24, 2011, Boeing won the hotly contested contract for a new generation tanker based on a revised version of the proven 767-200LRF (flown by many cargo companies) but with a 767-300 series wing, landing gear, cargo door and floor, flight deck and glass cockpit plus other updates.
The KC-46 design includes a permanent aerial refuelling boom and wing aerial refuelling pod systems, a capacity to carry 18 463L pallets (the KC-135 holds six) and medical systems for the transportation of patients in the aeromedical mission.
The aerial refuelling boom can transfer more than 1,200 gallons of fuel per minute (7,200lb), and more than 400 gallons per minute (2,400lb) from the drogue. The mould line of the new fly-by-wire boom is similar to the KC-10 but all hardware is new.
The KC-135 and KC-10 both have an air refuelling operator, a boom operator, located in the rear of the aircraft to operate the boom from a control station, watching the receiver aircraft approaching the tanker through purpose-fitted windows.
Boeing’s KC-46 proposal elected to place the air refuelling operator near the flight deck and manage boom operations from an aerial refuelling operator station (AROS). Cameras located around the KC-46 fuselage, operating in visual and infrared modes, feed their imagery to the air refuelling operator at the AROS.
Fitted with the latest communications and networking systems, including Link 16, the KC-46 also has armour around the cockpit, explosion and fire suppression, electromagnetic protection shielding and self-protection systems. The latter include Raytheon’s ALR-69A radar warning receiver, and Northrop Grumman’s AAQ-24(V) Large Aircraft Infrared Countermeasures system dubbed LAIRCM, which provides automatic protection for large aircraft against shoulder-fired, vehicle-launched, and other infrared-guided missiles.
Programme challenges
The KC-46 contract included $4.4 billion for the development and manufacture of four test aircraft. Additionally, Boeing received a $3.5 billion engineering and manufacturing development (EMD) contract.
The first KC-46A N461FT (c/n EMD-1) flew on September 25, 2015. Four test aircraft flew many missions and the EMD programme showed progress. However, Boeing ran into problems with the schedule. This was the first major programme seeking to secure both military and FAA certification at the same time for a single platform.
Lessons were learned in flight testing and many issues and required changes were identified. Boeing decided to continue building the aircraft and incorporate changes at later dates as they were confirmed. Development and production fell behind schedule and the programme went over budget. However, the US taxpayer was protected from footing the bill thanks to the firm fixed-price contract.
Keeping a check on the KC-46 programme, like all US government programmes, is the Government Accountability Office (GAO) which performs an annual audit. In its April 2018 report titled GAO-18-353 KC-46 Tanker Modernization, the GAO assessed programme progress and challenges toward achieving its cost goals and delivery schedule. The total acquisition cost estimate for the KC-46 tanker aircraft remained stable over the last year at $44.4 billion. As shown in the table below, the estimate has decreased about $7.3 billion (14%) since the initial estimate. This decrease is due in part to stable requirements.
In September 2017, US Air Force KC-46 Program Manager Colonel John Newberry commented: ““One of the risks we probably underestimated collectively was the concurrency of doing an amended type certificate on a brand-new aircraft — the 767-2C is a brand new 767 [that] obviously takes advantage of the heritage of the 767 family. Doing that all at the same time was underestimated [as to] the complexity and scope of effort. I think Boeing is now paying for those underestimates.”
In a 2017 article, former Boeing employee, Raymond Cosner said: “It’s not so simple to convert an existing commercial passenger jet into a militarized flying gas station. I should know: I helped prepare Boeing’s proposal for the KC-46A tanker. In addition to installing a first-of-its-kind refuelling system that will use both a refuelling boom and the hose and drogue system, new defensive systems, sensors and other electronic systems, will enable the KC-46 to operate in an increased threat environment. Wiring and hydraulic lines have been extensively modified, and numerous other changes are being made to enable the aircraft to perform its missions. Many of these advanced technologies are being used for the first time.”
Given the fixed price contract form, Boeing has had to write off more than $3 billion of expenses due to changes in the development of the aircraft and its systems. In late 2018, after many serious debates, reportedly the Air Force and Boeing agreed on a revised delivery schedule. On January 24, 2019, Air Force Secretary Heather Wilson reported that 36 KC-46As would be delivered in 2019.
KC-46A Phase II certification was completed in 2018 after the four test aircraft had flown more than 3,800 hours, and refuelled nine different types of aircraft; eventually 64 types of US and NATO aircraft will be certified for refuelling operations.
On January 22, 2019 a KC-46A refuelled a US Air Force F-35A Lightning II fighter over the desert skies near Edwards Air Force Base, California meeting a Phase III milestone in the test programme; this was the first aerial refuelling of a stealth aircraft by a KC-46A. Phase III certification testing and the type’s initial operational test and evaluation, all led by the 418th Flight Test Squadron, continue at Edwards Air Force Base, California.
A divine future?
The FY2019-2023 KC-46 production plan includes $20 billion to support production of 75 aircraft plus billions of dollars for base infrastructure construction and modification programmes. Production of the KC-46A is expected to continue until FY2027 when all 179 aircraft are planned for delivery.
In 2016, the US State Department filed paperwork concerning the potential sale of four KC-46 tanker aircraft to Japan. The first Japanese aircraft is now in production and the second will start soon. Boeing projects a market for up to 60 export KC-46 tankers.
The KC-X programme called for a 179 aircraft buy of KC-46As with options for KC-Y and KC-Z tanker programmes to fully replace the KC-135s, KC-10s and upgrade of US Air Force tanker capabilities. However, as a result of changing threat conditions and defence plans the Air Force, defence companies, think tanks and other groups have advocated different concepts for future tankers. US Air Force planning for a future tanker is now being re-evaluated and some KC-135s may have to stay in service longer. However, in early 2019 the US Air Force Chief of Staff, General David Goldfein commented: “I don’t know if it’s manned or unmanned, and I actually don’t care that much as long as it brings the attributes we need to win.”
Given that in August 2018 the US Navy committed to develop the MQ-25 Stingray unmanned air vehicle with aerial refuelling as one of its primary missions, it’s likely that the Air Force’s future tanker mix will include similar unmanned tankers. The MQ-25 was born of Naval Air Systems Command’s Carrier Based Aerial Refueling System programme.
Given the KC-46’s ugly tale to date, was there any positive developments for the program this year? Yes, if you consider the appearance of a KC-46A in the static display at the 2019 Paris International Airshow in June to demonstrate positivity. From an editorial perspective, flying a Boeing 767 from the United States to France is neither a new event nor particularly impressive!
Elsewhere, and by October Boeing had delivered 25 KC-46A aircraft to McConnell, Altus and Pease where additional deliveries were expected imminently. That’s a good thing for the Air Force, but let’s not get carried away with the number. At the same point in time there were as many KC-46 jets parked up at Everett and Boeing Field in Seattle as there were in service.
Perhaps a more significant fact is that production standard KC-46 aircraft are now involved in flight testing such that operational testing has been moving forward. On October 22, the Program Executive Officer for tankers formally certified the KC- 46’s transition into initial operational test and evaluation dubbed IOT&E. This phase will test the KC-46’s effectiveness, suitability, and mission capability toward accomplishing its three primary mission sets: aerial refuelling, cargo and passenger airlift, and aeromedical evacuation. The Air Force continues to flight test its new tanker, while Boeing continues to try and correct the category 1 deficiencies in parallel, a process deemed as the most expeditious means of achieving full operational capability. Despite the problems and delays, in October the US Air Force awarded Boeing a $2.6 billion contact for 15 KC-46 aircraft, spares, engines, refuelling kits and other systems. This was the fifth production lot awarded to the Chicago Illinois-based company for a total of 67 KC- 46A aircraft.
KC-46A Pegasus timeline
- January 2013 - DOT&E approved the post-Milestone B Test and Evaluation Master Plan, with concerns about adequate calendar time for correction of discrepancies or deficiencies between the end of developmental testing and the beginning of IOT&E.
- December 28, 2014 - First flight of the first EMD aircraft, six months late, primarily due to electrical wiring design problems. The aircraft began flight testing at the end of July 2015.
- January 2015 - The Air Force accepted Boeing’s Stage 4 (final build) test plans.
- May 2015 - DOT&E approved the Air Force Operational Test and Evaluation Center’s second KC-46A operational assessment (OA-2) plan to support the Milestone C decision.
- September 2015 - The first fully configured aircraft, EMD-2 started flying; originally planned for January 2015. January and February 2016 - Initial AR testing uncovered unanticipated axial loads in the boom that approached the boom’s structural limits, resulting in temporary suspension of further AR testing.
- July 2016 - Demonstration flights of Boeing’s redesigned the boom control system were completed.
- August 2016 - The KC-46A program successfully accomplished a Defense Acquisition Board Milestone C decision.
- November 2016 - DOT&E approved the Milestone C TEMP, with concerns about adequate calendar time for correction of discrepancies or deficiencies between the end of developmental testing and the beginning of IOT&E.
- Through 2016 - LAIRCM testing provided hit point distribution data to inform the vulnerability assessment and to verify both LAIRCM system configurations (Block 20 with ultraviolet missile warning system and Block 30 with two-colour infrared missile warning system) LAIRCM performance on the KC-46A.
- July 2017 - Naval Air Systems Command conducted EMP testing at Naval Air Station Patuxent River, Maryland on behalf of Boeing. Testing was not accomplished in accordance with the DOT&E-approved TEMP and the LFT&E Strategy. The NAVAIR testing demonstrated flight critical capabilities were still available after exposure to a 6dB pulse. However, testing did not fully demonstrate AR capabilities as required. The program uninstalled or deactivated multiple mission critical systems prior to testing and, therefore, their EMP tolerance was not tested on the aircraft in mission-representative configuration, nor was the functionality of the AR boom and WARP pods tested.
- July 2017 - The KC-46 program completed all planned flight test events necessary for the FAA Aircraft Amended Type Certificate of the Boeing 767-2C aircraft. FAA Supplemental Type Certificate test events continue to complete FAA certification of the KC-46A aircraft.
- August 2017 - A KC-46A deployed to Yuma, Arizona, for hot weather testing.
- October 2017 - Flight testing began to certify the AR system and the first eight types of aircraft for receiver operations.
- October 2017 - Flight testing began to certify the KC-46A AR system and the first eight aircraft for receiver operations, and will continue into FY2019.
- December 2017 - A KC-46A deployed to Guam for extreme humid weather testing.
- Through 2017 - Boeing completed Block 20 LAIRCM flight testing at Moses Lake, Washington to confirm installed system performance.
- Through 2017 - Testing ongoing of the production-representative version of the redesigned prototype boom.
- January 2018 - A KC-46A deployed to Fairbanks, Alaska, for cold weather testing.
- April 2018 - The Air Force completed KC-46A Joint Interoperability Testing with Link 16 with other aircraft.
- June 2018 - The KC-46A program completed follow-on developmental testing of an RVS software-only fix.
- June 2018 - The KC-46 program completed flight test requirements for the first KC-46A aircraft delivery by finishing test events for the RVS and the F-16, C-17, and A-10 receivers, and KC-135 refuelling the KC-46A as a receiver.
- June 2018 - Boeing completed Block 30 LAIRCM flight testing at Moses Lake, Washington to confirm installed system performance.
- July 2018 - A KC-46A deployed to Yuma, Arizona, for hot weather testing. September 2018 - Flight tests completed for FAA Supplemental Type Certification.
- Through 2018 - Initial centreline drogue system testing revealed deficiencies in software and hardware that resulted in unexpected disconnects during AR operations. Boeing identified the root cause and implemented new coupler tolerances and updated control software logic.
