In an effort to modernize its aging tanker fleet, the Air Force awarded Northrop Grumman a contract to build the KC-45 aerial refueling aircraft in February. The new tanker is set to augment and eventually replace the KC-135 Stratotanker, currently the oldest airframe still in use by the Air Force.
The first KC-135 was delivered to Castle Air Force Base, Calif., in June of 1957 and the last one was delivered to the Air Force in 1965. This makes the average KC-135 nearly 50 years old.
Though loyal to the aircraft, those within the KC-135 community recognize the need to invest in a new tanker, not because the aircraft is not capable, but because of its age.
"It's a great airplane and it's good at what it does," said Col. Peter Nezamis, commander of the Illinois Air National Guard's 126th Air Refueling Wing at Scott AFB. "The fact that it's still flying is a testament to that. But it's old ... real old."
With this advanced age come increased problems. Fuel lines leak, gear struts break, corrosion is rampant and replacement parts are becoming hard to come by. Most of the suppliers have either gone out of business or have gone on to build parts for newer aircraft.
"The parts for this aircraft are dwindling and becoming more and more costly to procure," Colonel Nezamis said. "And when we can't procure them, we have to manufacture them ourselves."
The aircraft themselves are on a set schedule that determines when they are sent to the Oklahoma City Air Logistics Center at Tinker AFB for a complete overhaul. The tankers receive new paint and any other identified repairs, which include replacing the boom "rudderevator," horizontal stabilizer terminal fittings and fuel bladders.
"Nobody envisioned that this aircraft would be around for so long," said Gaddis Gann, chief engineer at the center. "The KC-135 was designed and built in the 1950s era of 'throw-away' aircraft. Durability was not a major concern, and manufacturers adopted assembly techniques, such as lapping two pieces of metal without sealant, that made the aircraft corrosion prone."
These overhauls at Tinker AFB are becoming more important by the day. Workers at the ALC have to keep the KC-135 in operation for at least another 30 years.
"We're starting to see things break now that typically don't or haven't before," Mr. Gann said.
Even the inspection process has increased, as pilots and maintainers now check items that were unnecessary to check during the airplane's youth.
"When I started flying the KC-135 in the early 80s, our inspections were maybe one page long," said Col. Jeffery Glass, commander of the 507th ARW at Tinker AFB. "Now, we have five pages of inspections that have to be done on the airplane because of its increased age."
The KC-135's mission for more than 50 years is to provide the core aerial refueling capability for the Air Force and to ensure the accomplishment of its primary missions of Global Reach and Global Power.
Still, because of required maintenance due to the aircraft's age, the KC-135 is becoming less and less available to the fleet.
"You have to look at reliability rates as one thing, but then you have to look at the rates of availability for the airplane," Colonel Glass said. "And that keeps dropping."
At the 507th ARW alone, the wing only has five or six of its 12 KC-135s available to fly on any given day due to scheduled and unscheduled maintenance.
The aircraft was designed primarily to be an aerial refueler. Today, though, the Stratotanker is seeing increased use as a cargo hauler and is flying numerous missions in support of operations Iraqi Freedom and Enduring Freedom.
All of this also is combining to place additional stress on the airplane.
"We're pushing an airplane that's made of metal and is fatigued and old, and getting older, and things just start breaking down," Colonel Glass said. "The KC-135 has done its job and it has done it well. But anytime you get to the point where you have a 50-year-old airplane, you don't know what's going to break next."
This, he added, is one reason the KC-45 is a necessary addition to the tanker fleet.
"Without a follow-on tanker for the KC-135, if something happens where the KC-135 has to be grounded, we can't fight a war," he said. "If we don't have refuelers, we can't keep our planes in the air."
This is a fact Air Force officials recognized when deciding to introduce a new tanker.
"Recapitalization of our Air Force's jet tanker inventory is long overdue," said Gen. Duncan McNabb, Air Force vice chief of staff. "Air refuelers are a single point of failure in modern military operations. Across the spectrum of what we do, we absolutely rely on the capabilities they give to us."
The KC-135 is anticipated to stay in the fleet until 2040, and the KC-45 is expected to join the Air Force in 2013.