On June 2, members from the Utah Air National Guard’s 151st Maintenance Group, along with members from the 190th Maintenance Group, Kansas Air National Guard, took on the monumental task of removing the tail from a KC-135R after a hairline crack was found during an inspection. An undertaking the Utah Air National Guard has only needed to accomplish a handful of times since the 1970s.
It started when pilots from the 151st Operations Group had to declare an in-flight emergency due to un-commanded flight control movement. Once the KC-135R landed, it was impounded so a team could systematically troubleshoot the discrepancy to determine the cause of the un-commanded movement.
The un-commanded flight control movement was determined to be from a bad rudder Power Control Unit. The installation of the PCU calls for a specific inspection of the attach point from the PCU to the rudder. During the inspection Master Sgt. Amy Gauger, 151st MXG Non-Destructive inspector, found a 30 thousandths of an inch crack on the PCU mount by using an Eddy Current Machine.
“It was in an awkward location. Seeing the piece is difficult because there isn’t a lot of room,” said Gauger. “The way that the eddy current machine works, is it sends electrical currents through a solid piece of metal, and if there are any disruptions in the solidarity of the metal it will give a read out to the machine.”
After the crack was found, the aircraft was turned over to the 151st MXG Repair and Reclamation shop to be fixed. This mount is not repairable in the field, so the entire rudder had to be removed and replaced.
The KC-135R has a support bar that allows for the tail to be held at 90 degrees to facilitate rudder removal. This is called a fin fold which refers to the aircraft tail being unbolted so it physically lays horizontal while still being attached to the aircraft. In this instance, it was decided it would be easier to take the tail off completely.
“We took it off due to convenience and safety reasons, but it doesn't have to come off to work on it,” said Chief Master Sgt. Kelly Cummings, 151st MXG superintendent. “For this issue, it is easier to work with the rudder while it's on the ground. If it’s up in the air it will be difficult for maintainers to maneuver between the horizontal and vertical stabilizer.”
According to Cummings, removing the tail is rare. He said it has only been done four times at Roland R. Wright Air National Guard Base and once at Hill Air Force Base in order to transport Utah’s last KC-135E model aircraft to their museum for static display.
“It’s pretty unusual to have a crack in the tail,” said Cummings. “This particular aircraft was made in 1957 and the rudder has never been replaced, so it was likely caused from age and fatigue.”
Several years ago, retired Master Sgt. Dustin Pippen, from the 190th MXG, came to Utah to help assist and train 151st MXG members on a tail removal. To return the favor, two members from the 190th MXG, who had not completed the task before, were invited out to Roland R. Wright Air National Guard Base for this event and to train on how to successfully accomplish the large undertaking.
Extensive preparation and coordination were needed before the tail could be removed. Master Sgt. Landen White, 151st MXG Repair and Reclamation senior non-commissioned officer-in-charge, organized the project.
“We needed to coordinate with multiple shops in maintenance to help get ready to remove the tail, such as the hydraulic shop, communication and navigation shop, and the electro environmental shop,” said White.
They needed to ensure the cables were disconnected and clamped, pulleys stayed in place, hydraulic lines were covered, and many electrical wires were protected.
Since there wasn’t a crane big enough on base to pick up the tail, they rented a crane from an outside agency that could accommodate picking up and moving the 2,304-pound tail, measuring 25-feet wide by 21-feet high.
With a special cable assembly attached to the tail, safety observers, a crane operator, and those working on unbolting the four pins and bolts from the tail, safely removed, and placed it on the padded ground.
To help save costs, after hardware was removed, the 130th Engineering Installation Squadron brought their crane over to help detach the 875-pound rudder from the vertical stab.
“The 130th EIS has been helping us out a lot, and it saves us money by using their crane as opposed to having to rent another one from an outside agency,” said White. “They helped us pick up the rudder after we removed all the hardware from the tail fin, and they put the damaged rudder into the cribbing to ship to Tinker Air Force Base for repair.”
Lastly, the 151st Logistics Readiness Squadron assisted with the delivery of the new rudder. The refurbished rudder came out of Tinker AFB, Oklahoma, and costs approximately $85,000. After the refurbished rudder arrived, members from MXG quickly began preparations to reattach the tail to the KC-135R and get it safely back up in the air.
“I am impressed with the 151st Maintenance Group. They are extremely hard working and will stop at nothing to accomplish any job put in front of them,” said Col. Kurt R. Davis, 151st ARW commander. “It is truly an honor to serve with our Airmen, and to see them nurture their own capabilities, which drives and elevates the overall efficiency and credibility of this wonderful organization.”