This month, Boeing discovered the latest in a long line of problems on its KC-46 aircraft: some trim hanging over the emergency exit doors above the wing is preventing them from opening.
Although the KC-46 is designed as a troop transport as well as an air-to-air refueling aircraft, Boeing somehow missed this basic egress flaw in the tanker’s emergency escape system.
Every Boeing-designed commercial aircraft, including the 767 which is the base airframe of the KC-46, is tested during certification to ensure that all passengers can evacuate in an emergency within 90 seconds.
For this flaw-ridden military variant, which entered service in 2019, no such tests were carried out.
“We are carefully reviewing our processes to determine why this issue was not identified earlier,” Boeing said in response to questions from The Seattle Times.
The moment of discovery is awkward.
During a media roundtable last Friday, Air Force Secretary Frank Kendall told reporters that the Pentagon is unlikely to allow Airbus to compete for the next tranche of Air Force tankers, as planned, but will instead choose to stay with Boeing and request only “a modified KC-46.”
Secured with velcro
The newly discovered door trim issue affects all previously delivered KC-46 tankers, including the 57 already flown by the US Air Force and the two tankers in service with the Japanese military.
Boeing will have to modernize all these tankers once it finds a permanent solution.
In the meantime, Boeing issued a service bulletin to the Air Force with instructions to unscrew the piece of trim that interferes with the doors and secure it with Velcro instead.
Boeing said this provides “an interim solution to ensure the continued safe operation of the aircraft.”
In a statement acknowledging the issue, the Air Force said, “This change removes the associated emergency risk until a permanent modification can be made.”
Boeing said it identified the problem on March 17 “and immediately notified the Air Force.” The service letter with the temporary Velcro patch was issued on March 21.
The KC-46 is primarily an air-to-air tanker. For this mission, he only has one flight crew on board and they have their own emergency exit doors in the front part of the plane.
However, the aircraft can also be configured as an aft cargo cabin for an aeromedical mission transporting casualties or with passenger seats installed as a troop transport.
“There have been missions with passengers or an aeromedical configuration,” Boeing said.
The over-wing exits are there to help quickly evacuate this area of the aircraft. The Air Force statement said the door trim issue could “impede egress in an emergency.”
This wouldn’t entirely prevent passengers from exiting as there is another pair of emergency exit doors in the rear area which are unaffected by the door trim obstruction.
Boeing said no in-service events occurred that tested the overwing exit doors.
“In the more than 7,000 sorties flown by the KC-46, there have been no emergencies requiring the use of the overwing emergency door,” Boeing said.
Series of tanker problems
The company said it does not yet have a cost estimate to develop the fix and upgrade the tanker fleet.
The Army did not call the door trim problem a serious shortcoming, as is the case with the multiple previous design and manufacturing issues that plagued the tanker program and drove up costs.
Boeing has written off a total of $5.4 billion on the tanker since 2014.
In 2019, Boeing was forced to ground KC-46s while they were in flight testing after the Air Force became concerned about loose tools and other debris found at the plane. interior of completed aircraft.
The most serious outstanding issue concerns the remote vision system used to operate the aircraft’s refueling ramp. This requires a complete overhaul, a project that is expected to take several years.
Airbus, in partnership with Lockheed Martin, had hoped to take advantage of Boeing’s difficulties and offer its A330-based tanker for the Pentagon’s second major pending tanker contract.
And yet, last week, Air Force Secretary Kendall indicated that Airbus might not even have the chance to compete for this contract.
“As we…look deeper, the requirements start to look more like a modified KC-46 than an all-new design,” Kendall told reporters. “I think there is still a possibility of competition, but as we have reviewed our requirements, the likelihood of competition will decrease.”