TINKER AIR FORCE BASE, Okla. -- The KC-135 Stratotanker program was generating 30,000 mission incapable hours on balance panels and it drove the effort to find better repair mechanisms for programmed depot maintenance (PDM).
There are 23 panels per aircraft and the panels are the part of the wing that controls flight direction.
"We were to the point of pulling replacement panels from the 309th Aerospace Maintenance and Regeneration Group assets, and that limited the 76th Commodities Maintenance Group," said Sharmeitra Threatt, the 424th Supply Chain Management Squadron flight control program manager with the KC-135. "We were spending more money on repairs than it would cost to buy new parts."
Threatt said they were spending approximately $340 per hour on maintenance, or $25,000 to $30,000 per panel, just on manpower.
"Add in the additional man hours when it rolls over to a Management of Items Subject to Repair, after exceeding all of our repair capability. That drove up the price to $36,000 to repair a panel," she said.
PDM for the KC-135 takes place every four years. Overall, the savings for two balance panels over five years (75 aircraft per year) will be $3.2 million per year.
"This is a phased approach program, so we will gradually add two to four balance panels per year to the overhaul program until we have successfully overhauled all 23 balance panels," Threatt said.
Over the entire fleet of 447 planes, the panel repair savings is estimated to be $200 million and includes all 23 balance panels over 10 years. The savings are on repair cost-hours and material costs.
The 76th CMXG is creating an organic workload. The work is 90 percent of piece parts, but the goal is to get to 100 percent of in-house manufacturing. Currently the group is working to purchase the tooling needed to make hinges, then repairs will be 100 percent in house.
According to Threatt, the process of creating the new workload began with the delamination of the panels. Each panel is covered with a thin bonded aluminum skin, and when the skin delaminates, it allows moisture intrusion causing corrosion.
Part of the new workload would involve the manufacturing of bonded skin panels, development of crushed honeycomb core tooling and potentially the manufacturing of piano type hinges. The 424th SCMS partnered with the KC-135 System Program Office to get the integrated parts breakdown (IPB) drawn to accurately identify the piece required to build the balance panel.
"We need the IPB, it is (a) very important component," Threatt said.
Hinges are a major constraint for the balance panel project as well as other platforms.
"With the hinge manufacturing capability, we'll be able to build hinges for various weapons system including the B-52 (Stratofortress), B-2 (Spirit) and aircraft from other bases as well," Threatt said. "The technology is called gun-barrel drilling and we're conducting research now for getting the tooling so we can add that to our capabilities. This all stemmed from the balance panel project."
The new workload is a collaborative effort between the 424th SCMS, the KC-135 SPO and the 76th CMXG, Threatt said.
"No aircraft was grounded but it was getting to the point that the engineers said, 'we need better assets than this,'" Threatt said. "We would have depleted our spares pool by 2027 if we continued to pull from AMARG."
According to Threatt, the 100 percent panel overhaul program will begin in fiscal year 2016, with each section being phased in over the next five years.
"We can't do it all at once," Threatt said. "We have to give the manufacturers adequate time to get parts on the shelf."
There have been two actual fit checks on aircraft at Tinker Air Force Base for the first two panels and they were successful.
Threatt said the 76th CMXG kicked in repair capabilities in order to keep the planes flying when they couldn't receive parts off the shelf.