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Monday, December 1, 2008

Reinventing USAF Depot Maintenance

New life for life cycle management.

By Charlotte Adams

Major changes in life cycle management are in the offing at Warner Robins Air Logistics Center (ALC), one of the service’s three major depots for heavy maintenance. These changes, aimed at increasing aircraft throughput, will embrace not only hands-on work, but the requirements development, supply chain management, documentation and tracking processes. The changes will focus initially on the C-130 fleet. If all goes well in the prototype test period, the concepts are likely to spread to the Ogden and Tinker depots, to other weapon systems, and perhaps across the Air Force inventory and to other services. The concept, an umbrella term for many interrelated reforms, is known as High Velocity Maintenance, or HVM.

One of the instigators of the new approach is the Air Force Special Operations Command (AFSOC), which uses its fleet of some 100 specially configured C-130s heavily in the war on terror. AFSOC actually told Warner Robins they needed their C-130s back faster, says Ellen Griffith, chief of the Depot Operations Division at the Air Force Materiel Command. Special Operations’ assets are "a low-density, high-demand fleet, and they need every bit of flying time we can give back to them," Griffith says. "We desperately want to reduce the amount of time that we have aircraft like gunships down at depot."

The Need

A C-130 comes in for Program Depot Maintenance (PDM) about every six years and stays an average of 164 days. As many as 70 C-130s are on the ground at one time, either in depot or calendar-based "isochronal" (ISO) maintenance. HVM promises to reduce the number of aircraft on the ground, giving as many as 55 C-130s back to the operators. That’s $1.6 billion in assets, according to Doug Keene, HVM Product Team lead, as quoted in an internal Air Force news item.

HVM represents a big change in the way the Air Force does maintenance. The effort employs a mixture of productivity and quality enhancement tools derived from Lean, Six Sigma and the Theory of Constraints, but does so on a broader basis than before. In the past, Lean activities were limited to specific "silos," such as a maintenance wing, which often suboptimizes the processes. HVM "is the first time we’ve been able to look across all the organizations and how they affect each other," says Brian Keeling, who serves as "master sensei," or teacher, for the HVM High-Performance Team, a core planning group. Keeling works for Simpler Consulting, specialists in "Lean transformations."

Commercial Model

HVM seeks to emulate the best practices that ALC personnel observed at commercial maintenance operations run by organizations like American, Delta and TIMCO. One HVM target is speed. The commercial players can get a 500- to 900-hour a day "burn rates" of productive labor on an aircraft, compared with the Air Force’s 145 to 220 hours a day on the C-130, according to presentation by Maj. Gen. Tom Owen, director of logistics for the Materiel Command. (Both sets of figures represent multiple shifts.) Airlines, further, can get some 1,000 hours a day of labor on the MD-80, says Ed Pratt, the HVM team lead for information and technology. Many traditional depot practices are inefficient and time-consuming. Moreover, the existence of two, disconnected maintenance programs, field and depot, has led to duplication of activities and unnecessary inspections, according to an HVM white paper.

Air Force personnel who visited the airlines also noted that the carriers have more frequent inspections, which allows maintainers to better understand the condition of individual aircraft and make decisions about deferred maintenance. Furthermore, airlines have detailed work plans that maximize the efficiency of their workforce, a mechanic-centric focus, and a synchronized, continuous planning process that includes daily work updates and adjustments, according to the white paper.

By contrast, C-130 life cycle management today involves extremely long intervals between PDM visits. Between these 20,000- to 25,000-hour events — which amount to about 205 days of scheduled downtime per cycle — aircraft are grounded for periodic isochronal and home station checks, lasting 20 days or 3 to 4 days, respectively. And, since the ISO and PDM cycles are on different schedules, a C-130 might fly for 30 days after a PDM and then have to be set down again for an ISO, Keeling says. The long PDM intervals have resulted from various initiatives in the past to increase the amount of flying time and reduce costs, Griffith explains.

Up to 60 days after a C-130 arrives at the depot are spent "doing an Evaluate and Inspect (E&I) to find out what they need to repair," Keeling says. Once the problems have been identified, parts and tools are ordered, but mechanics have to wait for the material to arrive before they can start the work. When a mechanic is assigned a task, it’s up to him to collect the tools, materials and information to do the job.

Another consequence of lengthy depot visits is the "must fix now" mentality, with little flexibility to defer repairs for non-safety of flight items. In the case of the C-130s, there has also been "package creep." Over time, "If we ran into various structural or system issues on the C-130, we threw them into the [work] package," Griffith says.

New Thinking

HVM is "the first time I’ve seen a ‘clean sheet of paper’ approach to [USAF] heavy maintenance," says Tom Beil, director of site operations for Intergraph-Warner Robins, a recent addition to the HVM team.

HVM will divide Program Depot Maintenance into four, 13-day cycles at about 18 months apart, for a six-year total of 52 days. Each iteration will focus on a different area, e.g., fuselage/landing gear, wing, empennage and painting. The HVM office at Warner Robins plans to prototype its processes with four Special Operations C-130s, starting next year. Each 13-calendar day cycle will boil down to an average of 8.5 work days — six in the dock and 2.5 in pre- and post-dock operations, according to current thinking.

The Air Force expects to reap numerous advantages from shifting to more frequent, less variable depot cycles. Among those cited by HVM documents and Air Force officials would be the elimination of duplication between the parallel ISO and PDM systems (which would now be integrated); increased insight into an aircraft’s condition before induction; lead time for ordering parts and equipment, aligning funding, manpower and engineering support; and flexibility to defer non-safety-critical maintenance. The new approach also would maximize the use of kitting parts, materials, tools and information for the mechanics at the point of use, integrated planning and decision making, and more granular data collection. HVM also would involve continuous analysis of progress and adjustments of plans to meet goals.

However, another reason for consolidation is the shrinking of the "blue suit" maintenance work force, Griffith says. So it’s not a matter of HVM allowing the Air Force to trim the maintenance force, she explains, but a matter of dealing with prior cuts by using the work force more efficiently. (Currently about 21,000-strong, the USAF depot maintenance work force has declined by almost 13 percent in the last decade.)

Mechanic Focus

A key thread in HVM is its "mechanic-centric" focus. Today depot mechanics work in a job shop environment. Once assigned a task, a mechanic is responsible for gathering the drawings, parts, tools and equipment. So they spend hours standing in line at tool cribs rather than working on airplanes. "We know that a lot of our direct labor is out wandering around, looking for parts and tools," Pratt says. Under HVM the tools, materials and information would be preassembled and presented to the mechanic in a kit at the point of use — the aircraft. The contractors currently advising the HVM effort won’t actually build kits, Pratt says, but they will consider such questions as what a kit will look like, whether it will contain materials and tools for a whole day’s work, and how it will be presented to the mechanic. Plans call for the Defense Logistics Agency to assume the role of supply chain integrator.

Under the HVM initiative, Derco Aerospace is working under subcontract to M1 Support Services to devise processes for integrating mechanics’ toolkits. Derco is looking at questions such as how to make sure that tools and materials will always be available when needed, how to check out and return tools, and how to ensure that there are adequate triggers upstream in the process so that "everything queues together at the point of use," says Markus Heinrich, Derco’s vice president of U.S. sales. The current process is "ad hoc and stove-piped," he says. "We’ll take a number of stove-piped systems and integrate them into one point of use." It’s really a question of eliminating waste, he adds, including materials, tools, movements, distances, time and money.

The Air Force targets a large increase in the burn rate of productive labor. HVM aims to increase the amount of "touch labor" — where the mechanics are touching the C-130 — per day. The hope is to get up to about 250 hours per day by the end of the prototype period and double that to 500 hours in about a year. Eventually, the Air Force would like to get up to 1,000 hours of work per day.

These improvements will require daily standard work — preplanned daily agendas covering whole cycles — and "choreography" of the mechanics’ activities in "parallel operations." Griffith sees choreography as at the core of HVM. When a commercial airline pulls in an aircraft, she says, "it’s got a lot of people on it, but they’re not running into each other." It takes a lot of engineering to make sure the right tasks are being done simultaneously or sequentially. Choreographed daily work implies that each day’s work has been mapped out in advance, so that a support person can anticipate which tasks are coming and which items or tools will be necessary. Another issue is to revisit labor standards, to determine how long it takes to do the work, Griffith adds.

Work Cards

A key enabler will be the mechanic’s work card. Today it looks like an old computer key punch card and describes a task in narrative form, explains Intergraph’s Beil. Intergraph will help convert work cards into a graphical format, according to best industry practices, and help provide industrial engineering support in areas such as analyzing the layout of the shop floor and sequencing tasks.

The commercial-based work cards will be about 8.5 x 11 inches in size, using "lots of illustrations and just the necessary text to guide the maintainer from step 1 to step ‘n,’" Beil says. They will be like "one-stop shopping," he says, with all the information that a maintainer needs to complete a task. The devices are intended to help deliver "standard work" with consistent results.

Another practice that will enable more comprehensive task kitting is better advance knowledge of aircraft condition. So, when aircraft come in for an HVM cycle, mechanics will not only do the repairs for that cycle but inspect the aircraft for the next iteration, so that a bill of materials can be prepared for the aircraft’s return visit.

HVM also is eyeing the preparation of a more useful bill of materials, or bill of work, the document that lists the instructions, parts and tools needed to perform a given task. TCS, a subsidiary of L-3, is developing a comprehensive bill of work for PDM tasks associated with a C-130 variant. TCS personnel not only locate the data referenced in work cards (down to the page and paragraph), but also talk to the mechanics and look at the aircraft part involved in each task, explains Ken Railey, TCS project manager. The idea is for the bill of work to list everything the mechanic needs, down to the number, types and sizes of wrenches, the special tooling, stands, consumables and protective gear, so that the scheduler will be able to give the mechanic everything he needs to complete a task.

Tail Number Perspective

HVM also envisions more tailored aircraft maintenance. Today aircraft are managed by fleet rather than by individual aircraft and limited predictive analysis is performed, Keeling says. Among other things, HVM will capture data for predictive analysis that will help anticipate an aircraft’s needs before it arrives at the depot. HVM is establishing a "cave," or data repository for storing and processing historical data by tail number. Plans also will be more individualized. In the past, although there are some 13 different variations of the C-130, there was only one depot plan, he says. With HVM there will be 13 basic plans with variations on those plans to take into account the particular maintenance and operational history of individual aircraft.

The tail number approach also implies more knowledge about how the airplane was operated in the past and its condition before entering the depot. This knowledge allows advance planning, so that funding can be provided, parts ordered, and resources assembled at the time and place where they are needed. Requirements can be tailored to the aircraft and can be validated by checking on what the mechanic is doing. HVM will "take the wall out" between planning and execution, Pratt says, making maintenance more of a "team effort."

Another problem today is that the data is not granular enough. It may indicate that a part had corrosion on it, but not describe exactly where the problem was, for example. New Expeditionary Combat Support System (ECSS) software — an Air Force-wide solution, including MRO, bill of materials, product life cycle management and other components — is expected to improve the situation.


HVM is not just about the C-130, however. Rather, it is a process that is intended to be scalable, repeatable and deployable across all weapon systems. The Ogden and Oklahoma City ALCs may focus their HVM efforts on other aircraft. Eventually the approach could spread across the Air Force inventory.

Nor is HVM just about maintenance. Better life cycle management could directly impact acquisition, for example. The Air Force could plan to buy fewer F-22s if it knew that there would be fewer on the ground in maintenance at a given time.

The challenges to HVM are schedule and risk, as work transitions to the new system. A detailed transition plan is required to ensure that once an aircraft starts on the new cycle, it continues along this path. At the same time, other aircraft will be scheduled to come in for PDMs, creating a requirement for doing HVMs and PDMs at the same time, Keeling says. Warner Robins ALC, which does the majority of C-130 heavy maintenance, is looking at having both an HVM and a PDM line, or dual capabilities, during the transition. It will take five to six years to transition the whole USAF C-130 fleet of more than 600 aircraft to the new system. Although the jury is out at the moment, HVM promises to substantially improve aircraft availability and reduce maintenance cost. That’s definitely worth the effort.

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