More Factory Than Flight Line

Dec. 1, 2011

The US Air Force’s fleet is feeling the strain from pushing past two decades of nonstop combat operations in the Middle East and a decade of kinetic war in Southwest Asia. Airmen must continue to meet global demands with a thoroughly battle-worn force—one showing its age. Even if all the Air Force’s modernization programs stay on track, for the foreseeable future the fleet will continue to get older. USAF’s depot maintenance program is therefore a critical factor in keeping these aircraft healthy.

There are few places where this dynamic is more evident than the floor of Building 3001—the nerve center of the Oklahoma City Air Logistics Center at Tinker AFB, Okla. The 62-acre building, seven-tenths of a mile long, once housed a bomber assembly line, but today is jammed with widebody aircraft fuselages, engine work stations, sheet metal refurbishment shops, and other processes.

Along the KC-135 line, technicians work over an Eisenhower-era aircraft, stripping its paint. Nearby, several structural parts laid out on a table show exactly what ALC employees look for when a Stratotanker comes in for its five-year checkup and teardown.

A B-1B undergoes work at the logistics center at Tinker AFB, Okla. (USAF photo by Howdy Stout)

Tools and methods, such as using ultrasound technology, have evolved over the years, said Marshall Riley, sheet metal chief for the KC-135 line. But much of the work still relies on experience and eyeballs. He pointed at an aft fitting, a large structural spar near the middle of the fuselage, taken out of another aircraft and replaced.

“These were never supposed to come out of the aircraft,” he said, and when technicians do it today, they have to be careful replacing them; the engineering specs of the slide rule era of the 1950s and 1960s are often different from those of the computer-aided processes of today. It is fairly rare to replace spars, Riley noted, and a great deal more work goes into dealing with corroded wing skin, areas around the landing gear, and other common problems.

“It’s important to notice trends. If I find something common, I tell [inspection dock workers] to look at a certain area early on,” Riley said. Finding problems early on is as important as fixing them—it keeps the programmed depot maintenance (PDM) line moving.

Serious Business

This is daily business with Team Tinker, where more than 16,000 civilian ALC workers and airmen carry out this task painstakingly on some of the Air Force’s most in-demand but aged assets—from the KC-135 tanker to the B-1B and B-52 bombers.

The depot has its own rhythm and metrics, several leaders point out, as the enterprise has responsibility for delivering combat-capable aircraft to users around the world—and doing it quickly, cheaply, and effectively. In short, Oklahoma City ALC—the Air Force’s largest depot—bears more of a resemblance to a factory than a flight line. This factory will become even more important in the near term, as dollars and schedules receive scrutiny across the force.

Tinker, while the largest of Air Force Materiel Command’s depots, is one of three USAF locations where the service performs its heavy non-flight line maintenance, repair, and overhaul tasks on the bulk of its fleet. The other two locations are at Robins AFB, Ga.—home of the Warner Robins ALC—and Ogden ALC, at Hill AFB, Utah.

“Speed and quality,” Col. Cedric D. George, commander of Tinker’s 76th Maintenance Wing, said in an October interview when asked what factors he tracked in his daily work. George, a 24-year veteran maintenance and acquisition officer, had been on the job for six months, on the first depot assignment of his career. The maintenance wing has more than 9,420 personnel—making it the largest maintenance wing in USAF—and it annually racks up 8.5 million hours of labor on a range of aircraft and systems. Over the past two years, as depot maintenance processes have been scrutinized, more employees have been hired at Tinker, and performance metrics have steadily crept upward. “This is not just a pickup game in a resource-constrained environment,” George noted. “This is how we do business.”

The reality of maintaining and upgrading an old fleet—in an environment where funds will become scarcer in the coming years—is not lost on the ALC’s top leadership. “I think we’ve barely scratched the surface of our capability,” said Maj. Gen. P. David Gillett Jr., the ALC commander, during an October interview. He added there is “tremendous potential” to deliver capability more cheaply than today through improvements in process and productivity. “The challenge going forward in an austere environment is we are compelled to achieve those kinds of results.”

Johnney Kunnath, a sheet metal mechanic with the 565th Aircraft Maintenance Squadron, removes a panel for replacement on a wing trailing edge. (USAF photo by Margo Wright)

This is the basic tension of everyday business for USAF’s depots—with no significant infusions of cash for maintenance activity, and the possibility of cuts looming, gains will have to come almost exclusively from productivity and process improvements. The workers at Tinker know this well. According to most metrics, the PDM operations at the center have seen drastic improvement in the last two years alone.

Gillett, who retired last month, noted that when he arrived at Tinker nearly three years ago, the center had promised the Secretary of the Air Force it would reduce its flow days—the number of days an aircraft was worked on—and put more aircraft out in the field to meet demand. “We were not delivering to our promise in terms of PDM. Our programs were fine, but we seemed to be off track in depot maintenance,” Gillett said.

One example of success has been flow days for the KC-135 line. This is the largest programmed depot maintenance line in the Air Force, responsible for 447 airframes (as well as foreign military sales aircraft). The KC-135s averaged 226 PDM flow days in 2009, but had steadily come down to 159 days by the end of Fiscal 2011.

The Staggered Line Concept

The net result has been more aircraft to active, Air National Guard, and Air Force Reserve customers—from 46 deliveries in 2009, to 54 in 2010, to 58 this year, and 64 anticipated next year.

In 2010, the line exceeded its goal of delivered aircraft, implemented “kitting” programs, which slashed inspection times in the initial dock phase, and instituted a host of rapid improvement events cutting down time on tasks, such as installing carpet in cockpits, and speeding up supply time.

For its efforts, the center was awarded DOD’s 2011 Robert T. Mason Depot Maintenance Excellence Award, recognizing the KC-135 team’s efforts to transform its processes in 2010.

Other than safety, three metrics pervade the center’s work: speed, cycle time reduction, and quality.

In the KC-135’s case, officials with the PDM team implemented a “staggered line concept”—basically splitting off two lines of aircraft based on an initial inspection. Col. Robert Torick Jr., C/KC-135 system program manager, equated this to a triage point for the aircraft coming into depot. Based on what workers find, they then point the aircraft in one of two directions.

Most intense is the extended teardown cycle, involving major structural repairs that cannot be done concurrently with other tasks and taking about 82 days.

The speedy cycle, consisting of more routine tasks, only takes about 42 days.

“While the average age of the [KC-135] fleet is now 55 years, still, most of the fleet comes through and goes to a speedy PDM—about 60 percent,” said Torick.

Tinker’s depot must also care for some of USAF’s most in-demand combat aircraft, such as the B-1B fleet. While the Lancers are one of the Air Force’s newer aircraft types, they pose their own sustainment and maintenance difficulties.

“We have a lot of electronics on this aircraft, wiring harnesses, and other sensitive parts,” said Capt. Frank Faulhaber of the B-1B PDM shop, 565th Aircraft Maintenance Squadron. Much like other depot program improvements, Faulhaber said, the B-1 shop’s processes were “all over the map” in Fiscal 2010, but his team has worked hard to streamline procedures in order to turn aircraft faster.

The B-1 team has seen some success already. Work-in-progress aircraft, the number of airframes in depot not being worked on at any given point, have been reduced from eight to five, and “days in dock” for actual structural work are down to 87 from 99. The use of kits for parts and tools has expanded significantly, and flow days are down.

Aircraft work leader Russell Parris (l) and material expeditor Wesley Hugert check a KC-135 kit at Tinker. Having kits ready when needed has saved time that used to be spent waiting for parts and supplies to be gathered. (USAF photo by Margo Wright)

Even with PDM visits scheduled every five years or so, plenty of Southwest Asia’s combat trends have forced changes, Faulhaber said. New engine pre-coolers are being installed in the fleet, because there have been many maintenance issues with the older models in high Middle East temperatures. The component is crucial to regulating bleed air, for example, and if it breaks, hot air sprays all over other components surrounding the engines—creating big problems.

“When one breaks, it’s a pain for guys in the field,” Faulhaber said, and it can take upward of 18 hours to swap one out of an engine. That is 18 hours the aircraft is not turning sorties.

Every five years, the landing gear must be taken out and swapped—a process that can take under five days if done correctly, according to Jeff Spears, a section chief who works with most nonavionic components on the aircraft. Wheel well fires have been an especially pernicious problem in theater, Faulhaber said, so flex lines are replacing older fluid lines. These lines help contain hydraulic fluid leaks and lower accident rates as a result.

Maintenance is only one part of the equation. Sustainment—the engineering and upgrade work performed by engineers—must figure into it as well. “It’s not one in isolation of the other,” said Col. Mark T. Beierle, head of the ALC’s Aerospace Sustainment Directorate. “First and foremost, it is the user who sets requirements,” he said, then you have to look at the back end—the technology side and the laboratories—to anticipate what is possible in the future. If a given program can spend a certain amount of dollars to fix a sustainment issue, or a similar amount of money to fix a modernization issue, a choice often must be deliberated carefully.

Beierle points to the KC-135 line. While pushing down its flow days, the program also carries out some “ambitious” modifications, such as the just-completed multiyear $420 million Global Air Traffic Management avionics upgrade, the second major cockpit upgrade for the fleet. Now, the sustainment directorate has begun examining moving forward on the next upgrade for the aircraft’s avionics—new Communication, Navigation, Surveillance, Air Traffic Management (CNS/ATM) requirements for international flight.

Even with the new KC-46A program now progressing, the program office has to pay close attention to Stratotanker modernization, as the fleet will be in service for decades to come.

Sustainment is also an issue in smaller fleets, such as the B-2 stealth bomber or E-3 AWACS aircraft, Beierle said. Parts are critical, as the small fleets don’t necessitate large supplier bases. Engineering support from contractors is crucial; programs such as the B-2 have specialized engineering and materiel requirements. “These planes are art, and as you lose some of the artisans who built and designed them, that’s another challenge,” he added.

Elsewhere, new approaches to old tasks are taking shape, such as the maintenance of the F117 engine line—previously performed exclusively by the contractor, Pratt & Whitney, at its own facilities. Last year, P&W and the 76th Propulsion Maintenance Group signed an agreement to establish the F117 Heavy Maintenance Center at the ALC, a partnership for overhaul and repair for the C-17 fleet’s power plant.

P&W buys the maintenance labor from the ALC—from disassembly and inspection to reassembly—to satisfy the government’s requirement that no more than 50 percent of depot maintenance tasks are performed by contractors. By the time the second phase of the center is complete, more than 90,000 square feet will be dedicated to F117 maintenance at the ALC, said Floyd Craft, director of the 547th Propulsion Maintenance Squadron.

Constant Turbulence

In 2011, the center’s technicians have examined and repaired 11 engines, and Craft expects that number to rise to 46 in 2012. Currently an engine will take about 90 flow days, Craft said, but the target is to get down to 55. Many of the components and processes are proprietary to P&W, and ALC workers have a bit of a learning curve as they adapt to them.

Maj. Matthew Grimes (l) and Maj. Terrance Safforld run through a preflight check on a B-1. The aircraft, used for developmental testing, went through PDM and returned to Edwards AFB, Calif., ahead of schedule. (USAF photo by Margo Wright)

To improve performance in the future, Gillett and other leaders noted, process improvement will be first and foremost on the agenda, and this extends not only to the depot floor, but also to the supply chain itself.

Sandy Windsor, the maintenance support technical director for the 76th Maintenance Wing, must balance out the engineering requirements and personnel in a given fiscal year. Unpredictability of workloads makes the process challenging. If a forecast changes, or parts become unavailable, or not enough people are assigned a given task, the machine begins to break down. Inaccurate demand for parts, for example, leads to idle time on the depot floor. She noted, “On average, the maintenance wing has about 350 empty parts bins every day”—everything from nuts to actuators. Materiel support personnel ensure workers get the parts they need in a timely manner. One solution to improve availability and visibility was to move storage locations near the maintainer buildings. As of October, 27 shop service centers were spread across Tinker—holding key parts and components needed to complete work on a variety of systems and ensuring a supply line as short as possible.

As much success as the depot has experienced, the mission constantly evolves and the center must be prepared for the unexpected. Gillett said he is concerned about what tomorrow will have in store and what will be asked of the ALC. New programs such as the KC-46 will come online and present a whole new set of requirements and demands on top of legacy efforts.

“Things will not be like they are today,” he said. As budgets ebb and flow and hiring freezes and early retirements affect a portion of the civilian workforce, sustaining key maintenance, engineering, and contracting capability becomes a serious worry.

“Exactly the wrong people will leave or retire, and I’ll have mismatches in those capabilities,” he said. “It’s incumbent on the leadership to fix that.” New hires in areas such as engineering and the F117 engine program are great, but they must have the right skill sets passed on from more experienced workers at the same time.

The next few years will be “rough water” for the depots, Gillett said. “The one constant … will be turbulence. … The danger is, right now, we understand those processes, but in the future we’ll have to improve them. … There will be uncertainty and contradiction and lack of resources.”