PDF documents comprise the majority of service and parts information, yet it is difficult for IT systems to extract data from a PDF file. This limitation negatively impacts parts and maintenance operations for all industries; this post addresses the impact on aviation, but in future posts we’ll look at other industries beyond aviation.

The Role of Task Cards

Task cards (or “job cards”) are documents containing detailed instructions that guide aviation technicians as they perform maintenance on airframes, engines and components. Task cards are critical to ensuring fast, accurate maintenance and regulatory compliance. Task cards may be physical (paper) or virtual (electronic) documents, depending on the business process of the airline or third-party maintenance shop (MRO). Each task card contains the information (parts, procedures, tools, skills, etc.) necessary to work on a specific piece of equipment (by tail-number/serial-number) and must be signed-off when the job is complete.

PDF Maintenance Documents

The parts and procedures defined on task cards are based on OEM maintenance manuals but also include airline best practices, in the form of customer originated changes (COCs) or customer supplements. The ATA (Air Transport Association) recommends that these OEM maintenance manuals use SGML or XML as the data format; however about seventy percent of the manuals currently in use are PDF. (Component maintenance manuals, which make up a high percentage of the serviceable items on an aircraft, are provided almost entirely in PDF format.) This is a problem for maintenance organizations because SGML and XML are highly-structured formats that simplify data extraction; however, the lack of structure in PDF makes it difficult to convert the text into task cards.

Another issue is that OEMs update aircraft, engine and component manuals on a regular basis (typically quarterly), and often specify different parts and procedures for individual aircraft tail-numbers (or equipment serial-numbers). To ensure accuracy, each new OEM revision must be compared to previous maintenance manuals and combined with the relevant COCs and supplements before being converted into updated task cards. With so much PDF data being modified so frequently, airlines and MROs have difficulty synchronizing technical content for maintenance planning and execution.

PDF Limitations

Aviation maintenance manuals and parts catalogs are broken down into tasks/subtasks and assemblies/parts, which are readily understood by engineers and technicians. Regardless of the data format used for this information (SGML, XML, PDF, etc.), end-users will see little difference. It is when a software system (ERP, EAM, MRO, etc.) tries to utilize this data that the limitations of PDF become clear.

Maintenance manuals that use SGML or XML employ special identifiers that call out tasks, subtasks, parts and other relevant information. These data elements (TASK, SUBTASK, PNR, etc.) allow text within SGML/XML files to be recognized and utilized by other business and IT systems. PDF, on the other hand, is a linear stream of text without any content identifiers or embedded data elements (only formatting rules and a few metadata fields). As a result, for an IT system to extract data from a PDF file it must first search the document and the results must be interpreted to identify the proper information. This is a slow, error-prone process that eliminates the benefits of automation. To effectively use PDF, maintenance organizations are forced to cut-and-paste the necessary data from PDF into whatever planning and inventory systems they are using. To make PDF useful for maintenance automation, the SGML/XML data elements that are missing from PDF must be “inserted” in a way that allows it to act more like the other, richer data formats. Only then can the maintenance organization realize the potential of fully integrated IT systems.

Overcoming PDF Limitations

Enigma has the ability to overcome the limitations of PDF documents, processing them in a way that enables this relatively flat file format to act almost like SGML and XML data. Enigma’s tools enrich PDF files, allowing them to be leveraged by maintenance planning and execution processes, like automatic generation of task cards. With PDF data comprising well over half of the airframe, engine and component documentation, airlines and MROs are finding Enigma’s PDF tools to be critically important to improving maintenance productivity, accuracy and compliance.

To learn more about how Enigma enhances PDF, download our fact sheet, "Putting PDF to Work – Making PDF Data Interactive."

IT systems can help companies respond to maintenance emergencies. To highlight my point I’m using the situation at Southwest Airlines (SWA) as, in the wake of Flight 812, they work to address the problem of aluminum fuselage skin fatigue on their Boeing 737-300 aircraft. While I don’t know the details of how SWA and Boeing are responding to this situation, I imagine a lot of people are working long hours looking for ways to preserve safety and minimize the economic impact.

According to the National Transportation Safety Board (NTSB) the aircraft in question was in compliance with maintenance requirements, so this is not something that SWA did wrong. In fact, Boeing engineers recommended the 737 fuselage be inspected once every 60,000 take-off and landing cycles. Since SWA 737s average 6 flights per day that means an inspection every 10,000 days, or about once every 27 years. (The aircraft that suffered skin failure had only 39,000 cycles on it.) Boeing recently issued a service bulletin (SB) to change the inspection limit to 30,000 cycles (13.5 years). However the Federal Aviation Administration (FAA) has gone further, issuing an emergency airworthiness directive (AD) mandating that older 737s be inspected every 500 cycles, at least until the cause of the problem is known. For SWA, that means every 83 days almost 80 aircraft must be taken out of service to undergo electromagnetic inspection of the fuselage. For a company that runs a lean organization, changing the maintenance interval on an essential piece of equipment from once every 27 years to once every 83 days is a really big deal.

This raises a question for every owner/operator of capital equipment, “Does your IT system help you respond to maintenance emergencies?” Not every service bulletin or maintenance revision represents an emergency. However, real emergencies are unpredictable and it’s hard to know which pieces of information will be needed to resolve one. So perhaps a better question would be, “Is the information in your IT system accurate and complete?”  Since you don’t know when the next emergency is coming, and you don’t know what information will be required, it’s important that reliable maintenance and parts data is always available.

The first challenge to maintaining accurate and complete service and parts data is that different suppliers provide technical content in different formats. This makes it difficult for information to flow seamlessly across various IT systems. For maintenance departments, the time and cost required to standardize document types and data formats (e.g. S1000D, ATA 2200, PDF, etc.) can be substantial. However, during a maintenance emergency these costs are irrelevant as planners, engineers and mechanics need immediate access to all applicable parts and service information to fix the problem. In the case of an airline, the required data may come from Boeing, Airbus or any one of over 300 suppliers. (The situation is similar in other industries.) Since safety carries such high implications (both moral and economic) finding a way to resolve the issue of multiple formats, while providing complete and accurate service and parts information, is imperative.

The second challenge to maintaining accurate and complete service and parts data is the rate at which it changes. During a recent asset management conference I took an informal poll and found that maintenance planners believe about half the information in their maintenance planning and inventory systems is out-of-date. That’s not surprising because the work involved to cull through all the technical documentation and update the IT systems can be overwhelming. (Anyone who works with mission-critical databases will tell you that keeping them accurate can be a full-time job.) Technical information changes so frequently that many companies simply wait until the next scheduled maintenance, or until something breaks, to update the maintenance and parts data. (Even then, information rarely gets updated in all databases.) However, this approach leaves a company ill-prepared to meet the demands of an emergency.

Since regularly managing multiple data formats and updating multiple databases appears to be cost-prohibitive, but the cost of an emergency appears to be even higher, what should a company do? The answer is to automate. New and revised information needs to be automatically extracted from updated documentation (maintenance manuals, parts catalogs, etc.) and loaded into the various databases. This activity can be automated, occurring whenever documents are received from the OEM/supplier. Enigma’s InService Revision Manager processes updates, in multiple formats and at any frequency, to keep IT systems accurate and complete, which provides value far beyond the aviation industry.

If you have a maintenance or parts database that never seems to be up-to-date, you may be closer to a problem than you realize. Anyone that’s involved in the day-to-day scramble of equipment maintenance, or has lived through the turmoil of an emergency, knows that reliable information is critical to making good decisions. Enigma has the technology to ensure you’re prepared.

Deciding what to do when an OEM changes the maintenance procedures is a tremendous burden for many airlines. For most MRO modifications, choosing whether to adopt the new procedures is left up to the airline.

The industry hoped that by implementing XML/SGML documentation standards, smarter change management systems would emerge. And, with varying degrees of success, they have. (I’ve discussed this in a previous blog post, “Change Management for Aviation Data”.) But a lot of airline and OEM documentation exists in other formats, with PDF representing the largest share of this content. Unfortunately, PDF makes automated reconciliation more difficult than with XML. However, we find that with just a tiny bit of planning (and some smart software) there is no reason for PDF content to cause you trouble.

Many purists are quick to react to PDF content with condescending ‘legacy system’ labels. The normal response seems to be, “You’ve got PDF data? Too bad. You’ll have to deal with it manually until you replace the entire system with XML content.” As a software engineer, I understand the desire to deal with only one type of data, in a clean, structured format. But this idealism cannot withstand the realities of today’s industries, especially for airlines where the lifecycle of the equipment, and therefore the maintenance documentation, is very long.

Before describing how to implement change management on PDF content, let’s first recall the reasons change management is required: Airlines often modify the OEM maintenance manual to incorporate best practices, accomodate special needs, or include customized parts information. As a result, when an OEM revises the manual, airline personnel must:

1. Identify all the changes/conflicts between the OEM version and their own
2. Decide if the airline-generated content is still relevant in light of the OEM update
3. Choose whether to accept, reject, or edit the new OEM content
4. Then, and only then, distribute the updated airline content as the new version

In the days of paper-only distribution, change reconciliation was the #1 cause of delays in adopting new content, sometimes requiring more than 12 months to complete. Combining structured content, like XML, with Enigma 3C® Revision Manager has cut revision management from months to hours, by automatically incorporating changes wherever appropriate, and providing side-by-side comparisons for all potential conflicts. Conflict identification can occur at any level of granularity. (I.e., often a large task is split into many subtasks, and an OEM change to subtask 1 does not necessarily conflict with airline customizations on subtask 4.) When presenting the side-by-side comparison, areas of text that require review are highlighted and color-coded for fast comprehension and decision making.

Enigma’s intelligent revision management can also be applied to PDF content, allowing for granular comparison and update of PDF-based documentation. This means that PDF documents don’t need to be replaced wholesale; rather, specific PDF pages within larger documents can be reviewed and approved individually. When displaying conflicts, pages are still displayed side-by-side, with color-coded highlighting to guide the reviewer to each decision point. As PDF content often lacks metadata, we have also implemented smart file management for versioning and filename control, using Documentum® (or any popular document management system).

PDF content is viable and reliable for any maintenance environment—for airlines or any other industry. This is not to say that PDF is better than XML, which is an industry standard, but rather that PDF is more than a legacy format and should be treated as such. With the right software, reconciling changes in PDF maintenance content is a snap.