Airmen from an aircraft maintenance squadron examine inspection notes. Digital conversion can make data sustainment easier and more cost-effective.
Photo credit: U.S. Air Force

If your company stands as a significant defense contractor, you’re accountable not just to individuals, but to entire countries that depend on your technology and innovation to keep them safe. It’s a tall order that one manufacturer has succeeded in filling for decades with its defense and aerospace products and services.

A company founded on innovation cannot afford systems that slow momentum. During a military aircraft project with the U.S. Air Force, the manufacturer discovered that its maintenance documentation processes were not designed for optimal efficiency. In response, they enlisted the expertise of Data Conversion Laboratory (DCL).

Massive conversion project

One of the larger craft used by the Air Force relies on aerospace technology systems to keep it aloft and out of harm’s way. Those systems require extensive daily maintenance – 20 hours for each hour of flight – with each step documented in a granular fashion.

The job requires 140,000 pages of documents – a large catalog of technical manuals continually being updated as maintenance processes get refined and improved. The manufacturer, working with the Air Force, realized its existing portable document format (PDF), published from standard generalized markup language (SGML), while functional, did not lend itself to efficient updating. Staff members were manually updating content in multiple places. It was time-consuming, impractical, and not scalable. Converting to extensible markup language (XML) using the S1000D international standard for technical manual publications was a solution.

Project startup

When converting aircraft manuals, the operating principal needs to be trust but verify, and that goes double for conversion to the complex world of S1000D.

Ready access to standardized data may accelerate aircraft maintenance.
Photo credit: U.S. Air Force

S1000D is a conceptual departure from linear information, in which data are converted into a data module (DM) collection that can be:

  • Reassembled in multiple ways
  • Repurposed for multiple outputs
  • Reused across multiple products

Each DM is assigned a data-module code, a unique code used to manage the DM in the common source data base (CSDB), providing a mechanism for preventing data duplication. For the Air Force, this allowed the standardization of data, making sustainment of the data easier and more cost-effective than prior formats.

It was also the largest conversion to S1000D XML that the Air Force had ever attempted. DCL was selected to audit the results. For the audit, DCL created automated software tools that saved the Air Force time and money and provided testing and feedback to assure accuracy and quality.

Quality assurance

Working with the manufacturer, DCL developed customized quality assurance (QA) software to optimize conversion results for the manuals. The software was subject to rigorous testing and refining, requiring regular meetings with the manufacturer and the Air Force to update progress and discuss tweaks to maximize its efficacy.

Part of the quality control (QC) effort involved monitoring the automated processes and normalizing content where necessary to ensure a uniform process. DCL customized a QA process and tools that would optimize the results, allowing the creation of reports that:

  • Identify redundant content
  • Identify typos in data
  • Identify missed or incorrectly tagged cross references
  • Provide visibility into element mapping
  • Check tagging structure completeness (for example, that table structure was fully tagged)
  • Check content tagging validity (proper alert tagging, placement)

The conversion from SGML to a content-driven XML standard covered several manual types: infrastructure planning and delivery; job guides; fault isolation; work unit code; work cards; structural repair; general systems; and wiring.


The extensive feedback from DCL’s QA processes helped the aerospace manufacturer streamline and validate its process for updating technical manuals and facilitated the smooth conversion of the more than 140,000 pages to XML, replacing the PDF library. Benefits of the S1000D environment include:

  • Faster, more accurate sustainment
  • Ability to release change-only packages, instead of entire publications
  • More searchable, usable data
  • Ability to incorporate interactive capabilities
  • Ability to use content to populate an interactive electronic technical manual (IETM), software that allows users to navigate through multiple manuals efficiently and access part numbers, related procedures, and preliminary requirements quickly

The process produced 40,000 modules, each representing a logical breakdown (trouble-shooting, maintenance, etc.). These modules are searchable and can be extensively repurposed. The data require fewer pages, and updates can occur simultaneously across all relevant content.

XML document formats save time by eliminating the need for maintainers to sort through duplicated data or incorrect references in maintenance documents.
Photo credit: U.S. Air Force

The content is also well-suited to mobile formats.

DCL’s ability in and knowledge of automating QA checks, which otherwise would have been done manually, increased conversion turnaround and quality of the final product. For example, instead of spending one minute per page looking for duplicated data, incorrect references, or incorrect table structure with a manual process, automation can cut that time in half.

Prior to this project, when changes occurred to a publication, printing and distribution costs for every base that maintains that manual became quite costly. According to the Air Force, with the converted data, maintainers can instantly download changes to their computer, reducing those costs by 25%.

A final word

This project was the manufacturer’s largest-ever legacy conversion project to the complex S1000D standard. It proved so successful that the Air Force, an initial catalyst in this project, is in early development stages on other projects to mimic its achievement.

A common obstacle in content conversion is a hesitancy to invest in the process. When considering a conversion project, proper analysis, QA, and the right balance between automation and manual review should be considered. Tapping the expertise of a conversion specialist saves time in the long run, and produces a better final product.

Data Conversion Laboratory

About the author: Mark Gross, president of Data Conversion Laboratory (DCL), is an authority on XML implementation and document conversion. He can be reached at or 800.321.2816.