Progress in avionics technology used to make MRO service providers happy because it meant new opportunities to offer cockpit upgrades. That is still the case, but greater integration in avionics systems is creating a new challenge. While integration may help with predictive maintenance, it also makes it trickier to repair cockpit components—a key business for MRO service providers.
Airspace evolution capability, like Automatic Dependent Surveillance-Broadcast (ADS-B), is an example of a driver to update avionics, says Joel Conrad, Rockwell Collins principal program manager for air transport aftermarket. In European airspace, the TCAS II 7.1 standard has been mandatory since the end of last year, notes Sven Biller, head of avionic engineering at Lufthansa Technik. “This program was quite a challenge for the industry because all operators flying into Europe needed to complete this upgrade on schedule and all at the same time,” he says.
This kind of implementation of new operational requirements can easily turn into a major modification campaign for operators and MRO service providers, involving line replaceable units (LRU) modification, upgrading and replacement. “We completed this program in close cooperation with our customers and OEMs in a timely manner, but it took quite some effort, especially in the last two years,” Biller adds.
Sometimes an upgrade market is created by the obsolescence of an existing component. CRT displays, which have long since been replaced with LCDs in production, still have repair processes and spare parts available. Therefore, some operators never saw the necessity to upgrade to state-of-the-art LCDs. “But now the end of the tubes in the cockpit seems to be very near, since one of the last CRT manufacturers has just announced it is to discontinue manufacturing of CRTs,” Biller says. This could lead MRO service providers to another major upgrade and modification program, similar to the one for TCAS II 7.1 but this timne triggered by parts obsolescence.
Rockwell Collins already has developed a display replacement alternative for the Boeing 757 and 767. But sometimes operators choose to keep old technology flying. In that case, “our main problem is support from the OEM,” says Phillip Camp, European sales representative for Avionics Specialist Inc., an MRO service provider. To cope with obsolescence of spares, the company uses a variety of methods. These include Parts Manufacturer Approval (PMA) replacement, teardown of serviceable units and sourcing original makers of the parts for the OEM.
New technologies also prompt MRO engineers to devise innovative repair methods. Wear and tear affects panels and displays in the cockpit, which are quite heavily used. “Like on your smartphone or tablet, cockpit displays might receive scratches,” Biller says. A typical issue is scratches on the display of the electronic flight bag (EFB). But replacing such a unit would be too expensive. Lufthansa Technik has found a way to replace only the touch panel of the display assembly. “This is the most cost-effective repair,” Biller says.
One challenge is that this method requires skills beyond the typical avionics spectrum. “You need to establish a proper process for debonding the touch panel from the display and bonding the new one perfectly, both from optical and mechanical standpoints; it takes quite some labor, but the result, especially from an economic point of view, is worth the effort,” Biller says.
LED lighting is another of the new cockpit technologies having an impact on maintenance. Compared to neon and bulbs, “LEDs are much more reliable; and repair processes are a bit different,” says Olivier Boina, director of industrial development for Air France Industries-KLM Engineering & Maintenance’s (AFI-KLM E&M) component shop.
Self-programming components have an automated configuration procedure that depends on the aircraft to which they are fitted. They are easier to install, but an issue arises about the intellectual property (IP) in the software. To test a component, the MRO service provider needs to communicate with it, which requires access to the software. “We can reach an agreement with the system manufacturer or the airframer, enabling us to repair the component while complying with IP,” Boina says. This is only one example of IP becoming a widespread issue in cockpit maintenance, he notes.
A paradoxical challenge in cockpit maintenance can be found in the increasing reliability of computers. “We lack failure experience feedback,” Boina says. Meanwhile, control panels remain very repairable. Maintenance technicians mainly have to deal with electromechanical wear. Connections can easily be repaired and electronic components are accessible, Boina says.
A major trend in aircraft system architecture is greater integration. Avionics reflects the movement in two ways—it needs fewer components and it is at the center of a network. The latter can be seen as beneficial for aircraft design. For example, “this results in fewer LRUs, which have reduced weight and size,” Rockwell Collins’s Conrad says. In turn, the higher level of integration reduces the amount of wiring.
The tendency also can benefit maintainability. “Systems used to be relatively independent and are now increasingly part of a network—the Airbus A380 is the first aircraft with a really complete network,” Boina says. Even a pneumatic system can provide information, thanks to sensors. This opens the door for predictive maintenance.
FAILURE MODE AND EFFECT ANALYSIS
“When sensors on system A give indications of fragility, it may mean system B is about to fail,” Boina says. AFI-KLM E&M creates algorithms and uses its own expertise to improve failure mode and effect analysis.
A system network, combined with enhanced connectivity via satcom, cellular or Wi-Fi, is expected to facilitate maintenance. “Applications will continue to evolve that will provide improved efficiencies, both in the flight operations and maintenance operations domains,” Conrad says.
But the trend toward increased system integration also challenges engineers and technicians. “It becomes important that the ability to diagnose the system is retained, since the ability to just swap out an LRU will no longer be the standard troubleshooting method,” Conrad says. Instead, sophisticated maintenance logic will be developed, customized maintenance reports will be produced, and sending this diagnostic information off the airplane for analysis will become commonplace, he predicts.
The trend toward more integration started in the 1980s on the Airbus A320, but then it was at an embryonic stage, Boina says. The Boeing 777 followed suit, but its network was too small to exploit the capabilities of the concept, in his view. He adds that the A320neo, 777X and 737 MAX have stronger system networks, but they are not as capable as those on clean-sheet designs like the Airbus A350 XWB and Boeing 787.
Greater integration can be seen at the circuit card level. This is a major issue for MRO service providers, which want to keep the ability to repair them. “Electronic boards are becoming less repairable because of the higher level of integration,” AFI-KLM E&M’s Boina says. One circuit card can perform more tasks, which translates into trickier access to components. Some circuit cards even feature a multi-layer design.
“OEMs do not develop component maintenance manuals any longer because they estimate replacing a component on a circuit card is no longer economically or technically doable,” Boina explains. For an OEM, it is more economical to just supply a replacement card.
Yet “continuing to repair at the electronic component level is very important for us and for our customers,” Boina adds. First, replacing a resistor or an LED costs only a few cents or dollars, while circuit cards cost hundreds or thousands of dollars. Second, component improvement is at stake. “If we see that one area on the card repeatedly shows signs of fragility, we may want to talk to the OEM to make the system more reliable,” he says.
Dramatic changes in the use of cockpit equipment may be in the offing, as avionics can be expected to be at the heart of the “big-data” revolution. A recent Oliver Wyman study suggests the global fleet could generate upward of 98 million terabytes of data by 2026. The advent of big-data technologies will bring airlines unprecedented transparency into the condition of their aircraft, Oliver Wyman predicts. Computers in the cockpit and the avionics bay will process a lot of this data, providing maintenance technicians with more in-depth knowledge of an aircraft’s health.