Wireless Sensors To Increase Aircraft System Monitoring Possibilities
Increasing use of sensors is about to give maintenance providers an exhaustive view of an aircraft's health - we have just installed the first system on the Bombardier Q400
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Thierry Dubois - MRO-Netwrok
The ever-growing power of data processing is converging with another, less well-known trend to improve reliability and make predictive maintenance a reality: the increasing use of sensors, which are becoming cheaper or much smarter for the same cost. With a greater number of sensors or more intensive use of them, operators and manufacturers are better monitoring and understanding the behavior of many aircraft systems. Now the advent of wireless sensors is creating a new range of possibilities.
A combined enhancement in sensing and software solutions for the permanent assessment of systems is on the way to make aircraft more intelligent—and maintenance department managers will see it first-hand. "We are seeing an increased volume of new sensors available and more applications, which is starting to bring prices down," says Bjorn Stickling, manager of diagnostics, prognostics and health management at Pratt & Whitney Canada. Meanwhile, the materials and components that enable modern sensors
Still, what most users perceive as a tendency toward cheaper components is not so straightforward. "Sensors are becoming more intelligent through added software, computation and connectivity functionality; this functionality is providing great value to intelligent aircraft systems, but not without a cost," says UTAS's Wiegele. In other words, manufacturers can expect either a lower price or better value for their money. Nevertheless, "price is still a challenge on smaller aircraft," Stickling says.
Conventional wired sensors have been used mainly for control and fault monitoring; now they are increasingly being adopted for use on other systems, such as integrated health management. For example, Embraer is developing a scheduled structural health monitoring (S-SHM) solution. "It can replace complex and time-consuming inspections with simple and fast automatic evaluations of structural condition," says Bordais. "Our S-SHM solution is already flying with one of our E-Jets customers."
ATR and Meggitt Sensing Systems are developing a propeller-balance trending system. Vibration is monitored continuously, as is already the case for engines. Instead of having to arrange regular ground testing or putting maintenance personnel on revenue flights, the operator can receive much more frequent, automated reports. The bottom line is improved reliability, as an unbalanced propeller has an impact on engine accessories, ATR's Darsonval says. Maintenance costs are therefore predicted to decrease.
Among the factors enabling the design of such systems is the recent improvement of data-acquisition units, which are now more compact. ATR hopes to offer a retrofittable option.
Pratt & Whitney Canada is developing a similar system. "We expect to go into production in June on ATR aircraft, and we have just installed the first system on the Bombardier Q400," Stickling says. "It will allow airlines to put propeller-balancing maintenance activities into 'on-condition' mode, for a truly optimized environment."The next step for sensors is wireless communications, which is certain to be a far-reaching technology. For two years, ATR has been using wireless sensors for flight-testing purposes. Engine data are concentrated at the nacelle level and then sent to a central system. The experience gained in flight testing could be used to extend the capability to certified aircraft.
"We expect non-safety-related systems to be the first adopters of wireless," says UTAS's Wiegele, citing examples such as climate control. Next in line may be "smoke detectors, emergency lighting, cabin-pressure sensing, engine sensing and eventually flight-control actuation systems."
Wireless sensors currently certified for civil aviation offer higher memory capacity, improved wireless offload capability and longer battery life. As a result, they can record a greater volume of high-quality data in terms of sensitivity and frequency, Stickling says.
Embraer's Bordais is more circumspect. "We expect improvements on sensor resilience to interference such that new implementation possibilities are created," he says. The World Radiocommunication Conference in 2015 agreed on spectrum for wireless avionics intra-communications (WAIC). Standardization bodies RTCA and Eurocae are targeting the first half of 2019 to issue minimum operational performance standards for WAIC.
The potential benefits of wireless sensors are immense...