April 2006 
Volume 04, Issue 11 
Integrated Defense Systems

KC-135 maintenance transformed

New tools, techniques boost customer service and help position the program for the future


Above: U.S. Air Force KC-135s
undergo programmed depot
maintenance at the Boeing Support
Systems center in San Antonio.
Through a series of lean activities,
Boeing is shortening the amount of
time each aircraft spends at the
center, allowing more flexblity to
the warfighter.

Boeing and its supplier-partner Pemco Aeroplex Inc. are transforming the programmed depot-level maintenance (major-overhaul) processes for the U.S. Air Force KC-135 tanker fleet.

Through a series of Lean initiatives implemented at Boeing Support Systems in San Antonio earlier this year and scheduled for full implementation at Pemco's Birmingham, Ala., facility this fall, the team is accelerating the aircraft's return, thereby enhancing the customer's capabilities.

The Air Force, expected to select the prime contractor for the fiscal year 2008 KC-135 Programmed Depot Maintenance program in May, is requiring each aircraft to complete PDM in about 175 days. "At the beginning of 2005, we averaged about 214 days," said Liz Cange, an industrial engineer specializing in lean principles. "By the first Fiscal Year 2007 plane, we will be at 175 days or less."

KC-135 maintenance transformedA KC-135 tanker typically requires PDM every five years. Boeing inspects the aircraft and performs necessary maintenance and repairs, ensuring readiness for five years or more. Aircraft undergoing PDM are not available to support combat operations. Boeing's role, therefore, is to complete its work and return a quality product back to the Air Force as quickly as possible.

Lean maintenance is important, said Dave Ott, Support Systems Lean Enterprise focal, because it ensures mechanics and technicians only perform work that adds value, as defined by the customer. This process discipline improves quality, schedule and cost, in turn increasing customer satisfaction.

Boeing has transitioned KC-135 PDM from a dual pulse line to a more-efficient single pulse line that includes eight cells, or work locations. Instead of cycling work teams, tools and equipment between the two lines, the aircraft moves from cell to cell. Everything mechanics need to complete their work is located in the appropriate cell. The aircraft stays in each cell for an average of 12 to 14 days, during what is called a "pulse interval."

About 60 maintainers and managers helped kick off the improvements during a one-week workshop. "We asked the people who work on these aircraft to tell us the best way to flow the aircraft using a production/preparation/process (3P) event," Cange said.

The team is pleased with the results.

"It is amazing how much of a dramatic improvement is made by treating the mechanic as the centerpiece of the production system," said Sam Ferguson, Boeing Lean manager. "By bringing in everything and optimizing it for the person who adds the value on the production line, it's a huge shift in terms of performance."

The floor of the Boeing facility is filled with color-coded markings, so teammates know what equipment belongs in each area.

The tools to Lean

Here are some of the Lean tools used on the KC-135 Programmed Depot Maintenance (PDM) program. These tools support the companywide Lean+ initiative.

Aircraft Condition Analysis Tool: Analyzes the history of each aircraft, by tail number, to more accurately forecast needs.

Boeing On-line Management Applications: This Web-based application gives users quick, easy access to C/KC-135 engineering data. It also lets engineers make faster decisions.

Supply chain integration: Supply chain personnel are matched with and support the new production system, ensuring material is available as needed.

Job Management System: This software tool provides managers visibility into continuously updated cost, quality and schedule metrics. With a click of the mouse, they can determine the performance against contract requirements for each site, aircraft and cell. Users can retrieve data on open or closed work; against a specific tail number; and by a specific person, date, aircraft zone, part number. The data helps managers plan daily activities and address problems quickly.

Nonconformance Management System: The program uses this automated tool to log defects, create work orders and route work to the appropriate teammate. Used with iCapture, it allows inspectors to access data that helps speed the inspection process. The system's repair history feature helps Boeing predict the incoming condition of an aircraft and thus pre-position parts.

Shop Floor Management Visuals: These visual aids control the work cell by visually regulating operations and showing their status. Displays include location indicators, signboards, status boards (inclusive of performance metrics), checklists, diagrams, area maps, etc.

Support cells: Teams of estimators, supply specialists, disposition experts, quality assurance personnel and industrial engineers are assigned to support the eight PDM cells.

"The concept is much like how a surgeon operates on a patient," Ferguson said. "The tools are laid out in a standard way, and the operation is conducted in a standard pattern. Ideally what you are doing is minimizing the variation, and therefore you get a higher quality product a lot faster with consistent results."

Boeing is investing $6.5 million to implement lean improvements on the KC-135 PDM program in San Antonio. Pemco is making similar investments in its facility; once completed in September, that site's KC-135 PDM line will look exactly like the one in San Antonio.

In addition to the pulse line, Boeing has implemented

Integrated Gold (I-Gold). This third-party business-planning database provides a wealth of reports to track progress and improve processes. I-Gold integrates inventory databases with the shop floor management programs, allowing them to work together as a total enterprise package and eliminating paper-dependent processes. Using the integrated planning system, workers build job kits based on what the data tells them is needed.

iCapture. Mechanics use this third-party wireless tablet computer, which is linked to I-Gold, to document aircraft conditions that require repair or maintenance. "Our future state is to become totally paperless and to allow mechanics to access graphics and engineering drawings instantly at the point of maintenance," Ott said.

Kitting. This effort delivers to the point-of-use all parts, tools and consumables that a mechanic needs to perform a task. Kitting also involves team tools and task boxes, which prevents mechanics from checking in and out with personal tools or having to use a remote tool crib.

Task packages. Boeing has divided PDM work into easy-to-track task packages of less than eight hours work. "By breaking the work packages into less than eight-hour tasks, you can know halfway into the day whether the mechanics will complete that job, and you can more easily and accurately determine status of the work," Ott said. Workers can easily see if they are making appropriate progress, while managers know whether they are on schedule and budget. Also, Boeing can better accommodate customer changes by rebalancing the work line.

About 50 percent of PDM work is unplanned (repairs found needed when the aircraft is inspected), and most of that work is repetitive. As such, Boeing is taking a standard repair approach.

"When an unplanned maintenance action is required, and we have seen it or something similar before, we are able to readily access documentation and planning information using our iCapture tool," Ott said. "This improved process allows us to more efficiently define, order required material and schedule the repair."



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