What if every aircraft component incorporated its complete maintenance history on a computer chip embedded in a memory RFID (radio frequency identification) tag, with wireless access to the data via a handheld reader or interrogation device?
For airlines, the benefits are obvious. For example, take the maintenance records of oxygen canisters. Using an interrogator, a mechanic could walk through the cabin while the airplane is at the gate and get a quick reading as to when each canister was last inspected and what repairs were made, based on its serial number. Today, in most cases, getting that information requires taking the airplane out of service to physically remove the canisters, a time-consuming process given their installation within the overhead luggage storage bins. In addition, mechanics must hunt down the inspection records for each canister, which may or may not be readily available.
The use of memory RFID tags in aviation maintenance has moved at least to some degree beyond 2005, the start-up phase when the FAA issued its “Policy For Passive-Only Radio Frequency Identification (RFID) Devices.” That opened the door to application of the tags to flyable components. But to appreciate the potential impact on MRO, it’s necessary to have some understanding of the tags themselves, and where the concept is today.
Unlike “identification-only” tags, which contain a tiny amount of memory—usually 96 bits—to store the electronic product code number, and microchips to run the communications protocol to talk to the reader, high-memory RFID tags are embedded with additional on-chip memory storage capacity. In that regard, two types of high-memory RFID tags are available: dual-record tags, which can hold 1-8 KB of memory, and multi-record tags that can store between 8-16 KB of data. According to Bob Hamlin, chief technology officer of Tego, an RFID tag manufacturer, memory tags for aviation maintenance typically contain 8 KB of memory.
Along with a microchip for data storage, each tag is equipped with a miniature antennae. Transmission of the data to the interrogator is done via UHF waves. The radio frequency bands specifically designed for RFID tags are 915 MHz in North America and 865 MHz in Europe. The communication is two-way, which means the interrogator is also used to upload any new repair or service data to the tag.
“The tags are passive, in that they have no internal power source,” Hamlin says. “The microchips are powered entirely by the radio frequency [RF]energy received over the air from the interrogator.” He adds that the tags are compliant with the EPC Global second- generation (Gen2) hardware standard that defines the RF protocol and air interface for readers and tags.
High-memory RFID tags generally use flash memory (EEPROM) as their internal memory storage technology, enabling data storage for up to 5-10 years. However, Hamlin reports that Tego has developed an alternative technology to flash memory, allowing for data storage for as long as 30 years and at temperatures of up to 150C (300F). “Without the availability of this technology, most aerospace applications would not be able to use RFID,” he says.
The data initially loaded onto a memory RFID tag usually starts with the component’s birth record. That information, which is coded in by the OEM, includes the part’s number, description and serial number. “Multi-record RFID tags allow the technician to update this information to include every significant maintenance event concerning the part,” Hamlin explains.
Attachment of the tags by the component OEM can be done in one of three ways, depending on the part. Adhesive backing, reports Hamlin, is commonly used on seat frames, while a tie string is generally favored for oxygen canisters. For avionics boxes and engine components, tags are likely riveted or screwed in place.
Airbus plans to deliver the A350 with an approximately equal combination of dual- and multi-record tags, covering 350 part numbers and equating to 900 individual tags—all being supplied by Tego, according to Hamlin. “It will be the first Airbus product with the application of memory tags to flyable parts, including rotables, such as landing gear and repairable engine parts, as well as expendables such as life vests,” he notes. “The tags are being supplied directly to the component OEMs, which will enter the birth records prior to delivery of the component to Airbus,” he says. This enables Airbus to read the tags as part of its receiving process.
Direct delivery of the tags to the component OEMs, says Hamlin, allows them to select the best type of tag to use on each part, as well as the best way to affix the tag, taking into account possible modifications to the part in order to accommodate the tag. “Most important, the birth record data is originated by the OEM, making for a true birth record and setting up the data exchange the standard was designed for,” he points out.
Airbus has since decided to expand the tagging program to all other current production aircraft, starting with seats and life vests.
Field tests have proven the value of memory tags. In 2008, Boeing reported the results of case studies done in conjunction with Japan Air Lines, American Airlines and Singapore Airlines, involving oxygen canisters, ceiling panels, seats and crew rest areas. Citing just the time involved with inspecting the oxygen canisters’ expiration dates, cycle times of 6.5 hr. were cut to 8.5 min., for a 98% reduction. “Repairs that once required a maintenance hangar could now be done at line level, and inventory JIT control could result in a 50% reduction, with forward deployment to line stations.”
The A350 high-memory RFID tag program could represent a major milestone toward greater acceptance of the devices in aviation maintenance. It was in 2008 that Airbus issued a requirement for high-memory RFID tags to be applied to life-limited repairable parts on the A350, reports Todd Boyle, senior material and process engineer for Rockwell Collins. That company will supply Airbus with 30 different avionics components per A350, with attached 8-KB-capacity RFID tags. Each will be able to store approximately 100 maintenance records.
The components, which include communication, navigation and landing-related avionics, will be installed in the cockpit as well as in the unpressurized avionics bay. Rockwell Collins will write each component’s birth record on the tag.
Benefits will accrue to both Airbus, during forward fit, and Rockwell Collins at its service centers. “When the avionics boxes are delivered to the assembly line, the tags will make them easier for Airbus to identify and route to the correct location on the aircraft for installation,” says Boyle. “Rockwell Collins will also benefit, since the tags will provide more accurate information, especially in the event of a malfunction, because our first step will be to read the service data on the tags. If, for example, a field repair record is on the tag, we will know it, and hopefully reduce troubleshooting time.”
If the Airbus/Rockwell Collins experience with high-memory RFID tags is a positive one, it could encourage more OEMs and airlines to embrace the concept. Still, some convincing may be in order. One case in point is an experiment involving Boeing and Alaska Airlines.
In the 2011-12 time frame, Alaska Airlines implemented Boeing Commercial Aviation Services’ RFID Integrated Solutions program on its 737 fleet. “It was a well-planned, retrofit RFID-based system and process designed to improve maintenance operations,” says Mary Miller, a Boeing Commercial Aviation Services spokeswoman. “Although it gained regulatory acceptance and generated interest and enthusiasm among our customers, we found they were hesitant to implement the new technology at the time. For this reason, we pulled back the program over a year ago and are waiting for market demand to develop.”
Boeing would not cite specific issues its customer may have had with the technology, and neither would Alaska Airlines. However, as Rockwell Collins’s Todd Boyle explains, there were some problems with high-memory RFID—in a general sense—that were not necessarily related to the Alaska Airlines decision.
“Since 2008, when Airbus issued its request, several issues surfaced,” he points out. “For instance, the technology used by the readers was not quite ready. There were some reliability problems, along with a limited number of vendors. The technology had some growing pains, which have dissipated over the past two years.”
Boyle adds that a major driver for improvements to high-memory RFID implementation was a 2013 revision to ATA Spec 2000, developed as an e-business tool, and originally implemented by the Air Transport Association in 2009 for global airline and MRO use. “It was very helpful, because it provided clarifications concerning formats and data definitions related to high-memory RFID,” he says.
Kent Horton, Southwest Airlines’ director of aircraft engineering, reports that while there are no plans to add high-memory RFID as a maintenance component, any upgrades to the airline’s MRO enterprise resource planning tools are being looked at with RFID technology in mind. Still, Southwest is being cautious.
“When you get into RFID technology, you need to ensure extremely high data integrity with each RFID implementation. For us, that would mean a data capture and accuracy rate of better than 99%,” Horton says. “To do this, we would have to install new IT infrastructures to utilize the data on an optimal basis.”
The newer generation of MRO resource planning tools, explains Horton, are “mature enough and capable enough” to ensure nearly 100% data integrity. On the other side, he says, the airlines “would be facing a massive changeover” from their legacy enterprise resource planning systems to the newer-generation systems.
“The challenges with moving to an HM RFID, or any other automated data-collection process, within a legacy MRO ERP [enterprise resource planning] system are inherent in the data interfaces. There are no provisions in most legacy systems for many of the data types and fields afforded by high-memory RFID tags. Much of the integration work to be accomplished would be new programming within the legacy system. The return on any investment toward integration costs would be questionable, as some airlines look to replace their legacy MRO ERP systems in the next five or so years,” says Horton.