Thomas Barré started The Common Language project internally at Airbus. Now, the effort is on its way to becoming an industry standard for OEMs.
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Stepper motors provide precision for aircraft electronic expansion valves • Page 68 ALSO INSIDE:
Reimagine aircraft design with decentralized hydraulics • Page 64
With 3D printing, brushless dc motors, and high-speed digital controls, Domin is at the forefront of revolutionizing how the aerospace industry uses hydraulics.
Aerospace dramatically influenced hydraulics’ evolution in the last century. The move from manual to hydraulic actuation happened quickly in the 1950s and 1960s, yet fundamental hydraulic designs in aircraft have not changed as much since.
“If you look at some of the pumps on the 787, for example, they are probably identical to the ones that were on the 747 in terms of design — even though there were 40 years between them — for several reasons, not least of which is that they work and they’re good,” said Simon Jones, CTO of Domin.
Today, many aircraft have three central systems, each with multiple pumps and reservoirs. Power transfer units may be present if a pump fails to transfer pressure
between different systems. Each actuator also has redundancies with separate hydraulic and electrical systems. Plus, all this equipment requires extensive piping that adds immense weight, complexity, and assembly time.
“What you end up with are planes lugging between one-and-a-half and twoand-a-half tons of hydraulic equipment around with them all the time and burning hundreds of kilos of fuel per flight just to lift these hydraulics,” said Jones. “They generally all have two-stage valves constantly taking a few kilowatts of quiescent loss the whole time you’re flying. For an eight-hour flight, that’s a huge number of kilowatt hours just to power the hydraulics to do nothing. So, you’re caught in this world where
hydraulics are great, but having that hydraulic system on board is hugely costly in terms of infrastructure, size, weight, and power.”
Jones has an aerospace background and previously worked on gas turbines to reduce the weight of certain parts by tens of grams, even single-digit grams at times. He was hard-pressed to take every little piece of weight he could off the engine to get more out of the fuel. Every hundred grams of weight salvaged improved fuel burn by 0.1% and saved the company hundreds of thousands.
“The scale of waste in terms of the amount of energy needed to carry huge systems around on these aircraft is just baffling,” said Jones. “Hydraulics is great, but electrified systems are also great. The
best solution, therefore, should be bringing those two together and using the best of hydraulics without the clunky central stuff, giving it full digital control, and putting it into an electrified system.”
Domin poses to decentralize hydraulic systems and move toward hybrid-electric aircraft to leverage the best of both worlds while shrinking components, reducing weight, and decreasing energy consumption. Jones stated that hydraulics persists because of its power-dense force transmission but doesn’t lend itself well to lightweight electrified architectures, where digital signal transmission enables asset monitoring and optimization.
“The other nice thing is that you can manage redundancy by having multiple units or multiple redundant systems within a given actuator, for example. You can also locally manage energy storage, harvesting, and reuse,” he said.
However, capturing and reusing energy may not be feasible for all systems. For example, braking would be challenging due to its immense energy requirements, whereas flight controls have fully reversible cycles. Today, a big pump applies constant pressure through valves that are always on alert to lift and lower the flight control surfaces. This could be an opportunity to manage energy and eliminate losses so that no energy would be consumed.
“The reason it’s not done today is because it’s really hard to shrink hydraulics and get them to a point where they are efficient, small, compact, and lightweight. If you buy a pump, a valve, and an accumulator and bring all those together, you then have a big block. It just doesn’t work,” said Jones. “If you look at electrohydrostatic systems today, they look like a Frankenstein thing. There’s a few flying, but it hasn’t taken the industry by storm yet because it’s big, clunky, and generally prone to reliability issues.”
Since hydraulics don’t naturally shrink very well in this case, electromechanical actuators may seem like the sensible solution. However, for applications with high levels of shock, vibration, dirt, and temperature fluctuation, as is common for aircraft brakes, landing gear, and flight controls, such solutions can jam and compromise safety. They also must be sized according to the largest force they’d
have to exert and hold, drawing power the entire time.
“There have been billions spent on electromechanical systems for aerospace, and there are almost none flying. And the ones that are aren’t competitive with traditional hydraulic solutions,” said Jones. “So, we’ve identified this niche in the market where everyone wants to use less energy and have less weight. Everyone wants these modern digital systems, but no one can shrink and integrate traditional hydraulic systems nicely. That is the sweet spot for us.”
Domin’s core technology comprises ultracompact, high-performance pumps and highspeed switching valves. The company uses enabling tools, including metal 3D printing, to develop hydraulic products that allow electricity to generate and modulate pressure in a very complex, high-bandwidth manner. Though large-scale commercial aircraft are on their radar, the team has progressed in validating its products on helicopters.
“We’ve done a lot of work on helicopter braking systems. Today, they’ve got a pump on the top deck and pipe all these things down to the cockpit. The pilots have some pedals, and they control some valves. Then, there are more pipes down to the brakes, and you have a separate parking brake with another pump and accumulator. All those things can come out, and we can drop in a really small — the size of an apple — little hydraulic system next to the brake. That’s all control over wire, effectively, and we’re talking tens of kilos of weight savings, which is significant on one of those aircraft,” said Jones.
Shown here is an exploded view of Domin’s S4 Pro, its smallest direct drive servo valve.
But Jones and his team aren’t just looking to compete in the market — they want to make a positive impact on society while decreasing humanity’s footprint. He isn’t convinced that hydrogen and other solutions will be ready for a long time, so he’s thinking about what he can do right now to improve flying today.
“There’s obviously a trend of people who are motivated to look at the sustainability of things and the scarcity of resources,” he said. “But being sustainable doesn’t mean that people shouldn’t fly. It just means that we should make flying easier with a lower overall penalty to the environment.
“Engineers have the power to increase prosperity across the world. We have the power to deliver things that allow more people to do great things and give more people choices. We would love it if we made technology that meant there weren’t necessarily fewer flights, but more people would get on a flight and go and connect with people or see the world or travel — but while recognizing that the [resources] we have in the world … are scarce. Therefore, we should do our best to deliver things that let more people experience all that, but at a lower penalty than today. That’s where we’d love to get to.” A&D
Domin • www.domin.com
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STEPPER MOTORS PROVIDE PRECISION FOR
AIRCRAFT ELECTRONIC EXPANSION VALVES
Rachael Pasini • Editor-in-Chief
Precise, repeatable valve control within an aircraft’s environmental control system is critical for regulating cabin temperature. Here’s why engineers typically select stepper motors for the job.
An environmental control system (ECS) regulates an aircraft’s cabin pressure and temperature and includes an electronic expansion valve to manage air conditioning. This valve is integral to the system and requires precision control to efficiently regulate refrigerant flow, and subsequently, maintain crew and passenger comfort.
An electric motor actuates the electronic expansion valve via signals received from the ECS controller, which monitors cabin temperature. The motor drives precise valve regulation to control refrigerant flow into an evaporator. The evaporator receives air from outside the aircraft, which is heated by compression or through bleed air from the engine, and the blend of refrigerant balances air temperature within the cabin.
The electric motor and controls provide variable modulation, which
requires precision to refine refrigerant flow. Engineers typically choose stepper motors to open and close the expansion valve in small, controlled steps, with each step corresponding to a fixed angular movement. Depending on the motor's resolution, these steps or increments are measured in fractions of a degree, achieving the needed precision and repeatable control. The stepper motor also generates sufficient holding torque to maintain the valve’s position without losing steps when under pressure from the refrigerant.
“Depending on how the motor is designed, you can have large or small steps. For such applications, the best solution is to have quite small steps. So roughly, we can say, the step size is 7° with an accuracy of ±0.5°. In most applications, this is good enough,” said Adrien Mettraux, industry manager for
aerospace and defense at Portescap, a Regal Rexnord brand.
Although an aircraft’s ECS should include redundancy, protecting against motor failure is vital for minimizing maintenance costs and time. The stepper motor's design is inherently durable, as it does not rely on mechanical brushes to achieve commutation, nor does it need a feedback device or a complex closedloop controller. This simplicity also helps decrease procurement costs.
When selecting a motor for an electronic expansion valve, important considerations include torque, temperature, pressure, flow rate, reliability, and weight. Low weight and size improve an aircraft’s fuel efficiency and cargocarrying capability. Stepper motors achieve high torque density for their lowspeed operation requirements and do not require complex external electronics or
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This simplified diagram shows how high-pressure and high-temperature liquid from the condenser flows through the electronic expansion valve and into the evaporator. The controller receives signals from the pressure and temperature sensors and sends a signal to the electronic expansion valve to adjust refrigerant flow. Rachael Pasini/Design World
feedback. This advantage reduces the total weight and size of the package.
“We are in an aerospace environment, so weight is an important criterion,” said Mettraux. “Most of the time, weight is not as important when you have, let’s say, a system in an industrial building. Ultimately, the systems work in the same way, but in aerospace, you also need to consider weight when designing the complete system. Even at motor level, this is something we consider.”
The motor must also resist corrosion and operate for an extremely long time under varying environmental and operating temperatures.
“Now, we are using more sustainable fluids inside of the system. And the new challenge it creates is that the working temperature of the system is higher than it was in the past. So, we have developed hightemperature stepper motors, mainly driven by the fact that the temperature of the refrigerant is higher in the system,” said Mettraux. “We simulate and calculate the performance of the
motor at different working temperatures — not only at room and environmental temperature, but we also help our customers understand the behavior of the motor when the temperature is very low. You can start the plane at -40° C, so the system should work the same when the motor will be quite hot due to the high temperature of the fluid.”
Stepper motors are not the only solution, but they make sense for an ECS and operate as part of a closedloop system. Engineers often use
Can stack technology achieves reasonable accuracy and moderate torque. Portescap
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stepper motors in open-loop systems and can close the loop directly with an encoder that measures the motor's position. However, in an ECS, sensors measure the fluid pressure and temperature. The ECS controller closes the loop by sending a signal to the motor to move the expansion valve and adjust the refrigerant flow. The feedback is not directly done on the motor but through its sensors that communicate to the ECS.
“We are not speaking about extremely high speed compared to other applications for which the motor needs to rotate at 15,000 or 100,000 rpm. So, the stepper motor, in this case, is a good solution because it's open loop and the speed is not extremely high,” said Mettraux.
As an alternative to stepper motors, brushless direct current (BLDC) motors could enhance the speed and efficiency of control, while minimizing form factor and weight. While this design adds cost and needs external electronic controls, it could provide an advantage for aircraft that need more rapid changes in cabin temperature control. The more efficient operation of a BLDC motor can also add reliability and minimize the potential for overheating when under duress. However, engineers must also consider simplicity and cost-efficiency when selecting a motor for an aircraft’s ECS electronic expansion valve.
“The stepper motor is not extremely complex compared to a BLDC motor. It is simpler and more cost-effective for the application than a BLDC,” said Mettraux. “The stepper is a kind of BLDC because
it doesn’t have a brush, but a traditional BLDC motor could be a solution. It has very good efficiency, the speed capability is higher, and one of the main advantages of the BLDC is that you can work way above its continuous operation range. With a stepper motor, you can go above the continuous operation range, but with a BLDC motor, you can go way beyond [it], meaning you can get … more torque. This is due to the way the BLDC motors are designed compared to steppers. In some cases, BLDC could provide advantages … but it also needs a more complex controller driving system, and most of the time this is not required for electronic expansion valves.”
In addition, stack stepper motors can also be advantageous for some electronic expansion valve applications. This permanent magnet stepper motor uses simple techniques and designs to create an effective solution with reasonable accuracy and moderate torque. Customization might be required as part of the motor specification, particularly to enhance design integration. Features such as customized mounting plates, output pinions, and modifications to the motor itself might be necessary. A&D
Thomas Barré started The Common Language project internally at Airbus. Now, the effort is on its way to becoming an industry standard for OEMs.
TFOR AEROSPACE & DEFENSE
he creation of a common language to store and query data for the aerospace and defense (A&D) industry is underway, with original equipment manufacturers (OEMs) such as Airbus and Boeing set to benefit from widely recognized and accepted terms for parts and operations.
In late January, Thomas Barré, solution architect at Airbus, gave a presentation and answered questions about The Common Language project that he initially developed for internal use at Airbus. He shared this information in a webinar hosted and moderated by James Roche, A&D practice director for CIMdata, an Ann Arbor, Michigan-based
global strategic management consulting and research company focused on product lifecycle management (PLM).
Barré said that by mid-2026, The Common Language project is expected to be ready for application at scale. The language will offer OEMs beyond A&D with easy paths for people and machines to clarify, federate and pose questions to blocks of data.
“Prior to the development of this common language, OEMs have spent tens of thousands of hours searching for data without a Rosetta stone to navigate terminology and definitions. Point-topoint mapping across hundreds of IT applications must be updated each time
an application is added or modified. The [way] to overcome this obstacle is to create a standard — which is a consensus by nature — with key players of the domain. [This is] then available for application within aircraft programs as needed,” said Barré.
The language is built on International Organization for Standardization/ International Electrotechnical Commission (ISO/IEC) 81346, a series of international standards originally developed for construction projects such as buildings.
A next step for supporters of the language could be finishing the introduction of the knowledge created by Airbus into the ISO/IEC 81346 series and
Jessica Zimmer • Contributor
Adobe Stock
A
timeline of progress on The Common Language project. Thomas Barré of Airbus and the Aerospace & Defense PLM Action Group
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potentially Institute of Electrical and Electronics Engineers (IEEE) standards, with support from experts of the domains. Additional steps could include expanding the recognition of the standard to other standardization bodies and continuing to promote the language. Adopters and developers could work to set up internal and collaborative use cases of the language. With the support of the authors of the standard, Airbus has already developed extensions for additional domains, including energy transformation plants, manufacturing, processes, aircraft, and properties.
How the language works and solutions for legacy systems
The key action necessary to create the language is the attachment of a common language tag for definition to an object or process. For example, the tag “MMA” would be attached to a hydraulic cylinder. An OEM would not be required to rename the part.
An OEM should clearly differentiate between the tag and the elements that provide meaning about the object. Tags should not carry any meaning. Tags are stable over time and serve only to distinguish one object from another. This allows OEMs to continue using their own naming conventions for data and files. Currently, each actor in the aerospace industry has different naming and modeling policies.
“It would be utopia to move to a single naming and modeling convention. It is acknowledged [this] may be unrealistic,” said Roche.
By connecting data to a shared definition through the common language, the system can retrieve related information from different parties. This enables each actor to maintain their own naming and modeling conventions. This approach simplifies data
Software that automatically suggests definitions for aircraft components.
Thomas Barré of Airbus and the Aerospace & Defense PLM Action Group
management, promotes access and eases integration between OEMs and their supply chain.
According to Barré, the best way to promote the new language is to create a pilot project by using an existing project in which data is already being shared. Alternatively, an OEM could create the pilot program by shadowing the current data exchange methods to demonstrate the language’s performance. If there is no current project, the OEM could develop a new test project to apply the common language principles and showcase the benefits for interoperability.
Infrastructure for implementation and the standard for digital twins
An OEM using the common language should create a reference model that uniquely identifies each element without modifying its existing legacy system. An important step will be to distinguish between conceptual elements and their specific instances. For example, the idea of a bolt versus individual bolts used in operations.
A structured approach should simplify a user’s navigation of data and reduce complexity. The model offers flexibility and acts as a universal framework. An OEM should carefully consider implementation details. Legacy systems and new processes need to coexist.
Another ISO standard, ISO 23247, is applicable to digital twins. The latter is defined as digital models of a physical
product, simulation or process. This ISO standard provides some guidance on naming and identifying a subject’s digital twin. An OEM could merge the two approaches because ISO 81346 and ISO 23247 are fully complementary.
“ISO 81346 provides a language of concepts and definitions, acting as a dictionary and grammar to describe a system. ISO 23247 serves as a framework for digital twins in the industrial sector, helping create specific models of industrial systems for various purposes,” said Barré, adding that an OEM should use the common language from ISO 81346 to describe the elements within the models defined by ISO 23247. ISO 23247 specifies the key information to be included in a digital twin, while ISO 81346 ensures that each item within the model is described unambiguously.
The common language can be applied across industries because it provides a solid foundation for broader adoption.
“Organizations in any domain are encouraged to use this approach to enhance cross-industry understanding and interoperability,” said Barré.
Other requirements to work with the language
Through his last seven years of work developing and promoting the common language, Barré says the ability to label items required four elements: a standard for naming items that was based on
characteristics of that item, a protocol to attach a label to an item based on characteristics of the item; a means to extract those characteristics from sources in multiple formats, including tables and free form text; and automation of the process for labeling billions of items with a practical level of effort and in a practical timeframe. These elements helped the labeling proceed efficiently and on a massive scale without disruption to a business. Barré also developed artificial intelligence (AI) tools for automated labeling.
Barré is now freely offering the four methods and tools that he developed to peers. OEMs interested in The Common Language project can test the language for their own applications or participate in the standardization of the language by sending an email to common.language@ airbus.com.
One of the most significant statements that Barré made in the January webinar was, “Data is the new gold.” He added that OEMs that can manage and utilize data about parts and processes will be ahead of their peers. They will be able to retrieve any needed information from billions of data. A&D
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