Losses and Aviation Safety

USAF grounds entire fleets of KC-135 tankers, RC-135 reconnaissance planes, and WC-135 “nuke sniffers” to replace faulty tail pins

The inspections should take just 30 minutes and even before the order was issued, at least 90 KC-135s had already cleared the inspections.

Faulty tail pins caused the US Air Force (USAF) to order safety inspections for its entire fleets of KC-135 tanker aircraft, RC-135 reconnaissance planes, and WC-135 “nuke sniffers.”

These aircraft will be grounded until the faulty tail pins are replaced.

According to Air & Space Forces Magazine, the Time Compliance Technical Order (TCTO), issued Feb. 14, affects hundreds of aircraft. But the Air Force Life Cycle Management Center (AFLCMC) said the inspections should take just 30 minutes and even before the order was issued, at least 90 KC-135s had already cleared the inspections.

The Life Cycle Management Center confirmed to Air & Space Forces Magazine the authenticity of a memo (from which came the order) detailing the issue first published on the unofficial amn/nco/snco Facebook page.

The memo says that the USAF bought 280 vertical terminal fitting pins—tail pins—from a supplier between 2020 and 2022, but a subsequent quality deficiency report concluded the parts were faulty: actually the pins were the incorrect size, made with the wrong material, and insufficiently plated.

The memo stated that engineering analysis was underway to determine the durability and damage tolerance of the pins. But as said by Air & Space Forces Magazine the memo warned that the aft pins in particular carry much of the weight for the tail fin—and if one of the pins failed, the other would be unlikely to handle the load, a potentially catastrophic risk.

Although the memo does not say exactly how many of the 280 pins in question were ever installed, it states the tail pins on each aircraft are replaced during programmed depot maintenance. At least 200 aircraft could be affected according to a preliminary analysis of the depot maintenance data from 2020 to 2022. At the start of 2022, the USAF’s inventory included 394 KC-135s, 22 RC-135s, and three WC-135s.

This print is available in multiple sizes from AircraftProfilePrints.com – CLICK HERE TO GET YOURS. WC-135W Constant Phoenix 55th Wing, 45th Reconnaissance Squadron, 61-2667 – Offutt AFB, NE – 2015

Col. Michael Kovalchek, senior materiel leader for the Life Cycle Management Center’s Legacy Tanker Division, said in a statement that the decision to stand down the entire fleet for inspections was made “out of an abundance of caution, after consulting with our engineering experts. We are working closely with Air Mobility Command and all operational users and anticipate all potentially affected aircraft will be inspected.”

“We’re taking this action out of an abundance of caution, after consulting with our engineering experts,” said Col. Michael Kovalchek, Senior Materiel Leader with the Air Force Life Cycle Management Center’s Legacy Tanker Division, in an AFLCMC news release. “We are working closely with Air Mobility Command and all operational users and anticipate all potentially affected aircraft will be inspected.”

As of February 12, 90 aircraft had been inspected with 24 found to have non-conforming pins. Although no mishaps have resulted, leaders elected to accelerate the inspection due to a lack of information to assess the risk of materiel failure in non-conforming parts. Aircraft found to have non-conforming pins will be authorized a one-time flight to a repair location. The KC-135 Program Office anticipates aircraft which require only a swap out of new pins can be accomplished within a day. Most pin replacement work will likely be accomplished at the Oklahoma City Air Logistics Complex, where the KC-135 fleet also undergoes depot maintenance.

The 66 other inspected aircraft have been cleared to fly again.

From reconnaissance to airlift to flying command post, the C-135 has the versatility needed for an ever-adapting Air Force. The C-135 Stratolifter was the first strategic jet transport purchased by the USAF as a long-range cargo aircraft. The first C-135 was delivered to the Military Air Transport Service in 1961, five years after the KC-135 Stratotanker made its first flight for the Air Force. Boeing Aircraft built 820 –135s of which 732 were tankers.

Photo credit: U.S. Air Force

Dario Leone

Dario Leone is an aviation, defense and military writer. He is the Founder and Editor of “The Aviation Geek Club” one of the world’s most read military aviation blogs. His writing has appeared in The National Interest and other news media. He has reported from Europe and flown Super Puma and Cougar helicopters with the Swiss Air Force.

View Comments

  • This same inspection was done in the late 60's. We folded the fin and removed the pins. It was not a 30 minute job for sure. NDI folks used dye penetrant to complete the job. Of our fleet of WC-135B's we found at least 2 pins that had to be replaced. Remember we flew through a lot of turbulence. Later I was a flight engineer on the WC-135B's. Always a thrill a minute!

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