Strain Gage Sensors for More Electric Aircraft (MEA) and Fly-by-Wire (FBW): From the Drawing Board to Reality
“Sit back, relax, and enjoy a smooth and safe flight.”
From the drawing board to reality, commercial and military aircraft manufacturers are replacing older hydraulic and pneumatic control systems with lighter, more-efficient electrically driven systems; a trend known as MEA (More Electric Aircraft). Less weight, easier installation with simpler redundancy, rock-solid reliability, quicker response times, and lower damage vulnerability are all hallmark features of electrically driven control systems.
Hydraulic and pneumatic systems are subject to replacement. Hydraulic systems can be found in several flight controls such as secondary flight control systems, environmental control systems, landing gear, brakes, steering, doors, and many other actuation functions. Pneumatic methods can be found in systems for flight controls, cabin pressurization, cabin energy recovery, the engine, wing ice protection, and engine ignition.
Aviation design experts are convinced that newer electrical systems are more reliable and more efficient; they are encouraging many countries to invest in this direction and transfer more resources to it. The shift to MEA is expected to reduce the cost of production and the final product, improve propulsion efficiency, contribute to global green energy efforts, and reduce the environmental impact of aviation. By giving a direct input through electrical signals, commands can become sharper and more precise with less noise – providing overall safety to the passengers and more confidence to the pilots and crew.
Another trend in the aircraft industry is long-term structural monitoring throughout the aircraft, including airframe and engines. This requires monitoring the stresses experienced by various parts of the aircraft during flight. Wing stress, which can be related to wing-tip deflection, is one example. Strain gages, like the CEA-series offered by Micro-Measurements, are bonded to wing spars and the stresses calculated from strain data are reviewed during routine maintenance. These calculations expose the service loads experienced by the wings during flight. If found excessive, then the airframe is tagged for further review and possible reconditioning.
Detailed strain measurements can be used to understand the subtle influences on design and performance from every piece of the aircraft. Accurate flight data could also be used to conduct better flight performance from an airliner in turbulent conditions. Cracked, worn, or damaged parts can be detected early, before they cause problems
Another component of MEA is Fly-by-Wire (FBW), a class of control systems that are now becoming standard and common in many commercial and military aircraft. A FBW system replaces the manual flight controls of an aircraft with electronic interfaces. FBW aircraft controls allow for the replacement of traditional control yokes with computer flight controls that can be easily customized for different aircraft models.
Proper test procedures and the right strain gages and data acquisition systems will increase flight safety and further improve aircraft reliability. The weight savings resulting from programs like FBW and MEA can be re-allocated to additional revenue-generating passengers and cargo, while at the same time reducing maintenance costs and improving passenger satisfaction through fewer repair-related flight delays. Certainly, technological developments have reached the point where the values of control and system safety are well understood and have been applied to the flight control systems of many popular aircraft by Airbus and Boeing. These companies are working to reduce aircraft operating costs, reduce fuel, and, hopefully, make air travel an affordable option for passengers who must now rely on slower and a possibly less safe means of transportation.
We should also remember that the complexity of this process has increased as designers work to solve conflicting interactions between several equipment systems by enhancing the efficiency of each. Research in the last several years in the alternative energy and smart grid technologies has shown electrical systems tend to be more energy efficient and environmentally friendly than their hydraulic counterparts. To achieve the right solutions, each application and function on the aircraft must be considered on its own merits.
Using the best-quality strain gage sensors will contribute greater efficiency and understanding during program implementation. CEA-series strain gages and System 8000 data acquisition systems are expertly designed and manufactured to simplify the task of improving aircraft safety and efficiency.