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Military Aerospace Technology

A Quiet Revolution in Aircraft Maintenance

The handheld digital revolution is gaining ground with maintenance teams worldwide.

By Patrick Chisholm

The need to be global, mobile and deployable applies just as much to aircraft maintenance capabilities as it does to the aircraft itself. And in recent years, the process of repairing and maintaining military aircraft has become dramatically more global, mobile and deployable thanks to portable maintenance aids (PMAs) and electronic technical manuals (ETMs).

Maintenance technicians are not necessarily turning wrenches faster - the difference is that they are getting information much faster, thanks to e-tools. PMAs and electronic documentation allow the technician - whether on the flightline, in a hangar, depot or office - to perform tasks without leaving the duty location.

Surprisingly, aircraft mechanics spend as much as 40 percent to 50 percent of their time looking for information. The more complex the equipment, the more time they typically have to spend on research. The key is to reduce that research in order to have the maintainers focus on what they are paid to do - and above all, to improve the readiness and effectiveness of U.S. air power. "The faster you can get them the information that is relevant for the problem they are trying to solve, the more efficient or productive they are going to be," said John Snow, vice president of marketing and business development for Enigma Inc., Burlington, MA.

Thanks to advances in computing speed, storage, voice recognition, miniaturization and wireless communications throughout the Air Force - as well as in the other services - maintenance technical data is gradually being converted from paper into ETMs, and the use of manual documentation is gradually being converted to electronic means. Going hand-in-hand with that change is the growing use of PMAs.

Aircraft with digitized technical data include the F/A-22, CV-22, C-17, B-52 and the next-generation Joint Strike Fighter. All technical data for new aircraft, and almost all data for engines, have been digitized. Some older aircraft have digitized data as well. However, most of the latter - particularly those potentially going out of the inventory - often lack such digitalization. "Economically it might not make sense to digitize that tech data because there is a cost there. But data for all of our new aircraft and equipment are digitized," said Lieutenant Colonel Mack Breeland, chief of the Air Force's Maintenance Information Systems cell at the Pentagon.

Types of digitized documentation involved may include task cards, inventories, mechanical drawings, technical orders, maintenance manuals, parts illustrations, service bulletins, job guides, fault isolation manuals, illustrated parts breakdowns, structural repair manuals and inspection work cards. Basically, anything that currently exists in technical data format can be transferred to electronic format.

While desktop computers cannot be used at the flight line, PMAs can. These are mobile e-tools used at the point of maintenance, typically taking the form of a ruggedized laptop computer or a handheld device.

The Air Force began studying PMAs in the early 1990s and started using some devices in the mid-1990s. But it only has been within the last few years that PMAs have become more common.

Under the Integrated Maintenance Data System, all logistics information components will be integrated into a single, Air Force-wide maintenance information system, providing technicians with software, hardware and infrastructure solutions at the point of maintenance, while also providing integrated capabilities across the entire maintenance enterprise.

One E-Tool for the Job

PMAs enable four basic capabilities: to open and close work orders; to order parts; to track parts through the system (thanks to automatic identification technology or AIT); and to access and view technical data. They also can be used to perform advanced diagnostics and interact with experts at remote locations.

"Those are the four pieces we are trying to put on the one e-tool for a job," said Breeland. "We don't want our technician to have a computer for documenting the maintenance, a computer to order the parts, a scanner to read the barcode label, and then one to do the tech data. We want all that on one e-tool. That's what point of maintenance is."

PMAs are typically small instruments but can be large as well, weighing up to 25 pounds. They range from inexpensive commercial off-the-shelf (COTS) devices to ruggedized units customized for military use, which can cost as much as $20,000. Generally, PMA hardware takes two forms: "thin-client" and "thick-client" devices. The thin devices contain very little memory, but can be updated frequently. Thick-client PMAs are larger, containing memory and more processing power.

Depending on the type of PMA, the Air Force has used various brands. For hand-held terminals, they include Intermec and Symbol. For ruggedized laptop computers, Itronix and the Panasonic ToughBook are common brands. The Air Force's air logistics centers are commonly using Fujitsu. The Air Force also has tested Xybernaut wearable computers, which are worn on a vest or a belt.

There are many other products as well, including DataTrak products, Sanders' Enhanced Diagnostic Aid (EDNA), the Walkabout Hammerhead, AMREL Rocky Patriot III ruggedized notebooks, Compaq & Palm handheld devices, and the Dolch NotePAC II.

There is also the CROC - compact ruggedized operational computer - manufactured by Tactronics, Westhampton Beach, NY. It was originally designed for special operations, but Tactronics found that it is conducive to maintenance environments as well. "A lot of the same reasons why the special ops guys want that laptop are extremely germane to other people, like maintenance technicians, who have to operate in rugged environments - where there's dust, dirt, rain, and those kinds of things," said Bill Silhan, president of Tactronics. The CROC, he says, is also useful in bright sunlight, thanks to a special optically bonding coverglass to the display.

Tactronics also makes the Tri-Sector Access Point, enabling portable Wi-Fi networks that can be placed in hangers or elsewhere where maintenance technicians operate, giving them connectivity to the central server. "They access the main database with a laptop and the schematics come up locally on the laptop," said Silhan.

One type of wearable computer projects what is on the screen onto the inside of one's glasses, letting a technician read instructions while performing a repair, freeing up both hands to do the work. This technology was tested at Hurlburt Field and Tinker AFB. However, Breeland said sunlight and other factors reduced the practicality of the product.

PMAs improve data accuracy and speed of information flow by doing it at the point of maintenance versus waiting to subsequently document. The information is automatically fed into a database. The Air Mobility Command (AMC) has phased in other functions to include links to the illustrated parts breakdown and quick reference list, as well as e-mail access through the local intranet. In cases where a wireless LAN is being used, the data is immediately transferred to the main database, improving data speed and accuracy.

"In addition to the standalone PMA out in the field that helps with productivity and efficiency, data can be sent back to a central mainframe server or a cluster of client/server servers and really help in knowledge management," said Mike Binko, director of communications for Xybernaut, Fairfax, VA. "So it's a symmetrical data flow - not just taking data out into field, but also bringing more accurate data back in."

Paper documentation is still used frequently in maintenance activities. When members of the aircrew show up at the aircraft, they typically review the paper forms to ensure they know the aircraft's current status. Then, when they are ready to document their maintenance actions, most technicians enter the information in electronic form, albeit not until returning to their duty station where desktop computers are located. "Our future concept is for maintenance data collection to be completed at the point of maintenance. Using wireless technology, the data will immediately be updated in the system," remarked Breeland. It is anticipated that this practice will be available to maintenance technicians whether in garrison, deployed to an established forward base, or when establishing a presence at a bare-base location.

"There can be a maintainer on the flight line, and by the time he gets back to his shop to put his entries in there, he may have forgotten what exactly it is he did to take care of the maintenance. Or he may be in a hurry and make shortcuts, so he doesn't get the same opportunities to input the same kind of data as could be captured automatically," said Frank Hale of ARINC, a contractor with the Maintenance Information System cell.

In the future, PMAs may be able to communicate directly with weapons systems. "Direct connections between PMAs and the equipment being repaired facilitate rapid analysis of system performance characteristics and allow faster transfer of critical information for ordering parts, reporting work performance, and receiving updated technical information," according to a report carried out by the McLean, VA-based Logistics Management Institute (LMI) on behalf of the Department of Defense. Current obstacles to such direct communication include information security concerns - particularly when dealing with wireless - and bandwidth. Fortunately, because most maintenance information is sensitive but unclassified, sufficient protection may be available through COTS products such as data encryptors and virtual private networks.

For wireless operations, advantages include time savings/instant data access, more accurate and up-to-date data, and more efficient utilization of personnel, where more people perform direct maintenance rather than support functions.

Software, of course, is also key to enhancing the efficiency of maintenance technicians. Snow explained that each piece of equipment has to be tracked independently and each has a different maintenance history. What one jet engine may need another one may not, or they may have different attributes and therefore may require different replacement parts. Mechanics may spend a lot of time just trying to decipher what it is that they need.

Snow's company develops Enigma 3C, an interactive product encyclopedia that allows technicians to type in the serial number for a particular piece of equipment and get access to the most up-to-date service bulletins and other data that is relevant to that component. "What you start to find out is that there are anywhere between five and 10 different places that mechanics typically have to go to find information about how to fix equipment, which is why they spend so much time looking for information," said Snow. "What we do is consolidate all that diverse information into a single, integrated product encyclopedia."

Enhancing Data Mobility

In the Air Force, many major commands and bases have implemented PMAs. The Air Force has formally sanctioned two point-of-maintenance test bases, Hurlburt Field, FL, and Nellis Air Force Base, NV. Testing at Hurlburt Field has focused primarily on development of point-of-maintenance software to be used on hand-held devices, and testing at Nellis has centered on use of ruggedized laptop computers.

Twelve AMC bases have fielded wireless technology on their flightlines, and they are using e-tools to document maintenance. Other bases have fielded, or are in the process of fielding, point-of-maintenance-type capabilities using various types of e-tools. All three of the Air Force's air logistics centers are using e-tools and wireless technology to document various maintenance and financial actions.

The EDNA device has been used with the F-16, F-117 and B-2 aircraft since the mid-1990s. According to the LMI report, the device appears to be virtually indispensable for complex diagnostics, operational flight plan upload, and flight data download. The DataTrak Model 20 has been used with the F-22.

In the Marine Corps, technicians working on the AH-1W Super Cobra helicopter have tested a maintenance mentoring system that aids in troubleshooting and diagnostics, according to LMI. It consists of a ruggedized tablet-style computer, developed by Intelliworxx Inc., which a maintenance technician can wear or carry. The primary interface is voice recognition, with a touch-sensitive screen as a backup. There is a Web browser as well, from which the technician can access additional information.

The Air Force Research Laboratory has conducted usability studies of various e-tools including the Xybernaut head-mounted display wearable computer and wrist-mounted wearable computer. "We anticipate that once fully tested and found effective by the testing community, widespread use will be forthcoming," declared Breeland.

Challenges Remain

LMI concluded that before PMAs can be effectively employed in DoD maintenance environments, several challenges must be addressed. They include poor readability in sunlight, short battery life, and environmental factors such as temperature extremes, moisture, corrosion, vibration, electromagnetic interference and dust, which can seriously degrade the performance of some PMAs. However, sunlight problems can be overcome with photo sensor technology, which can enhance readability. Obviously, these are not as large concerns in the hangar environment compared with the flight line. However, with wireless communication there can be a slow response time due to the amount of metal in the hangars. Remedying this requires upgrading wireless LAN infrastructures.

For portable electronic display devices, other problems have included the following: touch screens sometimes stopped working, batteries died quickly, words were sometimes too small on the screens and schematic displays could be hard to read.

Also, carrying the tablet in a pouch suspended from a strap around one's neck can be awkward, and the cord connecting a headset to the tablet is a potential safety hazard. In addition, the pointer used to interface with the tablet's touch screen can be a source of foreign object damage.

Insufficient integration with existing maintenance management systems and emerging maintenance automation initiatives have adversely affected some DoD PMA initiatives as well, such as with the F/A-18E/F program.

Cultural resistance is another challenge. In the LMI study, about a quarter of the technicians were initially uncomfortable with computers and were reluctant to use the EDNA. Researchers found that older technicians seem more resistant to the technology, while younger ones are less critical of it. To help overcome cultural obstacles, effective management focus and adequate user training are essential.

Breeland expects manpower studies conducted in the future to help quantify specific improvements provided through use of e-tools and new technology, but currently, the only quantification of performance is done in an informal, indirect manner (i.e., word of mouth, trip reports, etc.). The activities are not well enough implemented to warrant the development of an evaluation program/module. Nevertheless, there can be no doubt that PMAs and ETMs are revolutionizing the way military aircraft are maintained.