While the positives and negatives are well-known, the behind-the-scenes impact is less clear. One area that could change significantly is maintenance, repair and operations (MRO). Airlines and specialised companies work around the world to ensure aircraft comply with regulations, minimising time on the ground and protecting passenger safety. Providers have enjoyed relative homogeneity in the technology used by fossil-fuel-powered aeroplanes, but might now have to learn new skills and techniques thanks to the introduction of pure-electric and hybrid powertrains in planes and flying taxis.
According to Kevin Michaels’ MRO Industry Outlook, 40% of the money spent on air transport MRO in 2016 was on engines. Hybrid systems using turbines to charge batteries could shrink and simplify engines and lead to a decrease in the MRO aftermarket, Nikhil Sachdeva from consultancy Roland Berger told MRO-Network.com.
Batteries will inevitably decline over time, however. They can degrade in high operating temperatures, while high discharges over time can have negative effects. Harmful structures known as dendrites and whiskers can form in lithium batteries, potentially breaching separators and causing fires.
New inspection and repair protocols are needed for high-power batteries, according to research entitled Maintenance Considerations for Electric Aircraft and Feedback from Aircraft Maintenance Technicians from the Georgia Institute of Technology. Thankfully, MRO providers should be able to replace batteries rather than repairing them on the aircraft, potentially simplifying the process.
Elsewhere in the powertrain, the researchers said electric motors will create new challenges. “Although an electric motor may generally require less maintenance than an internal combustion engine, motors are not maintenance free,” said the team. “High-speed bearings inside the motor cores will need to be monitored for condition and replaced at regular intervals. Windings can short out from contaminants, abrasion, vibration or voltage surges, which would require the motor to be removed and rebuilt. Thermal damage of insulating components is also possible, which could result in performance loss.”
One firm aiming to simplify motor maintenance is MagniX. Developing and using its motors in a modified Beaver seaplane and the nine-seater Eviation Alice, the firm has designed its technology to be easily maintainable.
“Right now electric motors are all podded as a single unit to maintain or reduce complexity, but that means you need to replace the entire motor [after a fault],” said MagniX CEO Roei Ganzarski at the 2019 Paris Air Show. “What we’ve done is make it completely maintainable… you can take one coil out and replace it, you can take one magnet out and replace it.”
This modular and reconfigurable approach “allows a much higher degree of maintainability, which to airline operators is very critical because they want longevity,” said Ganzarski.
New approaches to MRO necessitated by electric aircraft will coincide with wider technological changes. Research institutions and companies are increasingly developing inspection and repair robots, such as the CompInnova project’s suction-enabled Vortex Robot. Autonomous drones could cheapen and simplify inspection of large aircraft, while human workers are being tooled up with more ‘smart’ technology such as tablets and mixed-reality headsets.
These technologies could ease the introduction of electric aircraft, working seamlessly with the simpler powertrains. Batteries and motors can be designed with software integration from the start and will easily join Internet of Things networks, enabling predictive maintenance and automatic component ordering.
Despite the potential improvements to emissions, the industry will be slow to electrify. MRO must nonetheless be agile and responsive to stay ahead of developments, ensuring aircraft stay in the air and passengers travel with the same level of safety as they do today.
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Content published by Professional Engineering does not necessarily represent the views of the Institution of Mechanical Engineers.