WASHINGTON — The Air Force is speeding up its hunt for a faulty component on hundreds of KC-135 Stratotankers that, if it failed in flight, could cause an aircraft’s tail to fall off.
Air Force Materiel Command on Tuesday directed maintainers to inspect the entire KC-135 aerial refueling fleet, as well as the RC-135 family of reconnaissance planes and the WC-135 Constant Phoenix radiation‐sensing jet, for potentially faulty tail pins before their next flight.
As of Sunday, 24 of the 90 KC-135s that were inspected had noncompliant pins, the Air Force said. Planes with the proper parts have been cleared to fly.
The components, formally known as “vertical terminal fitting pins,” help attach an aircraft’s tail fin — its “vertical stabilizer” — to the rest of the fuselage. The tail gives pilots control over a plane while turning.
“We’re taking this action out of an abundance of caution, after consulting with our engineering experts,” said Col. Michael Kovalcheck, senior materiel leader in the Air Force Life Cycle Management Center’s legacy tanker division. “We are working closely with Air Mobility Command and all operational users and anticipate all potentially affected aircraft will be inspected.”
Checking the pins takes about half an hour, AFMC said Wednesday. An earlier order, issued Feb. 10, called for the aircraft to be inspected within 15 days.
The service owns about 360 KC-135s, plus around three dozen RC-135 and WC-135 variants that are based on the same Boeing-built fuselage. The Stratotanker fleet entered service in 1956, followed by the RC-135s in 1964 and the WC-135s in 1965.
KC-135s with problematic pins are allowed to fly to a repair shop that will replace the part, AFMC said. The KC-135 program office said the fix can happen within a day, and most will take place at the Oklahoma City Air Logistics Complex, which is where the Stratotanker undergoes depot maintenance.
A leaked memo that was posted to the unofficial “Air Force amn/nco/snco” Facebook page Feb. 9 first said 207 KC-135s may have had faulty pins installed. The Air Force confirmed the memo’s authenticity to Defense News.
The memo noted that the faulty pins may have been installed during planned depot maintenance between June 2020 and December 2022. Each KC-135 has a pair of pins, one on each side of the vertical stabilizer, and they are replaced during every round of heavy maintenance.
Metallurgical analysis conducted on two nonconforming pins in January found several discrepancies. They were too small, made of the wrong material, and had insufficient plating, the memo said.
If even one were to fail in flight, the results would be catastrophic, the Air Force said.
“Should one pin fail, the other would not be able to carry the remaining load and the vertical stabilizer would depart the aircraft,” the memo said.
The Air Force is in the process of retiring its KC-135s to make way for the new KC-46 Pegasus tankers. Active duty Stratotankers are based around the world at Beale Air Force Base, California; RAF Mildenhall, England; MacDill AFB, Florida; Kadena Air Base, Japan; McConnell AFB, Kansas; Joint Base Andrews, Maryland; Seymour Johnson AFB, North Carolina; Altus and Tinker AFB, Oklahoma; Fairchild AFB, Washington; and nearly two dozen Air Force Reserve and Air National Guard installations.
The RC-135 and WC-135 fleets are headquartered at Offutt AFB, Nebraska.
Rachel Cohen joined Air Force Times as senior reporter in March 2021. Her work has appeared in Air Force Magazine, Inside Defense, Inside Health Policy, the Frederick News-Post (Md.), the Washington Post, and others.
Stephen Losey is the air warfare reporter for Defense News. He previously covered leadership and personnel issues at Air Force Times, and the Pentagon, special operations and air warfare at Military.com. He has traveled to the Middle East to cover U.S. Air Force operations.