In December 2019, Aerospace Tech Review published, ‘Twinning: Digital Twins Show Their Power’ by Louise Bonnar, one of ATR’s regular contributors. (It can be found online at www.aerospacetechreview.com.) This article explained the concepts of digital twins and digital threads, and how the aerospace industry is using them to significantly improve equipment design, performance, and maintenance.
Two years after publishing ‘Twinning’, ATR contacted aerospace companies who are using digital twins/threads to update us on their progress. Here’s what they told us.
A Digital Twin/Thread Refresher
Before delving into this progress, it seems sensible to reintroduce the concepts of digital twins and threads, so that the updates that follow are in context.
According to Dale Tutt, vice president of Aerospace and Defense with Siemens Digital Industries Software, “the digital twin is the precise virtual representation of a physical product or process. In aviation, the digital twin is being used to help design new products or make changes to existing products faster, because engineering teams have a rich, robust understanding of the product and how it performs.”
Although digital twins are virtual representations of physical products, they are more than just 3D models residing in cyberspace. To faithfully recreate these products and support realistic testing to aid their physical counterparts, digital twins incorporate “all of the data and models needed to represent the different aspects of the products’ behavior or production process,” said Tutt. “This can include requirements, simulation models, analysis models, bills of materials, and any other data that is needed to define the product or process. Most importantly, the comprehensive digital twin evolves over the full product lifecycle so that it can be used to simulate, predict and optimize the product or production system.”
Meanwhile, the digital thread “is the interconnection between all the different representations and models, linking all of the digital twin’s capabilities and providing digitalization and traceability throughout the product’s lifespan,” Tutt explained. “In aviation, the digital thread provides seamless transitions from the product design to production to maintenance and support, establishing the flow from ‘as-designed’ to ‘as-built’ to ‘as-maintained’.”
Now that we have refreshed the concepts of digital twins and digital threads, here’s how they are being used by OEMs and MROs.
Boeing Using Twins/Threads in Commercial and Defense Aircraft Sectors
Boeing has adopted digital twinning/threading as fundamental tools to advance aircraft manufacturing and maintenance operations in both its commercial and defense businesses.
“In the commercial aircraft sector, our data analytics team uses digital twin and model-based engineering tools in working with airline customers to address issues, for example, the air-conditioning system,” said Darren Macer, Predictive Maintenance and Health Management technical fellow with Boeing Global Services. “The team has created and currently maintains operational digital twins of components to track each individual component’s unique characteristics and detect degradation rates.”
Boeing has the capability to create digital twins whenever new physical components are installed. It can then use digital threads to update these digital twins to reflect changes to physical components when the data exists. “With this capability we can identify proactive removals of components that have degraded and are able to suggest targeted maintenance actions, such as heat exchanger cleaning, to prolong the on-wing time of other components,” Macer told ATR. “In short, operational digital twins can prevent unscheduled or reactive maintenance with scheduled, targeted maintenance actions.”
In the defense aircraft sector, the U.S. Air Force is using Boeing’s digital twin methodology in the B-52 Stratofortress’s Commercial Re-Engining Program, (CERP), in which the BUFF’s legacy Pratt & Whitney TF33 engines will be replaced by yet-to-be-chosen modern commercial alternatives. (The B-52’s popular BUFF nickname is short for “Big Ugly Fat Fellow” according to the USAF, or something less polite but equally respectful in common parlance.) “These 3D and mathematical models of all physical hardware allow us to evaluate airplane performance without ever touching the airplane,” said Macer.
Meanwhile, Boeing is using digital twinning to predict and find possible fatigue maintenance hot spots in the F15 Eagle. “Using crack and corrosion findings from the fleet, depot maintenance, and customer feedback, we’ve created a digital twin to plot the data and identify or modify inspection areas more accurately,” Macer explained. As well, “Boeing built the new F-15EX on a digital thread to maintain low operational and maintenance costs: By analyzing identical processes and infrastructure as other F-15 variants (supply chain and maintenance procedures), we’ve developed a digital twin to predict depot maintenance and aircraft fatigue.”
GE Aviation Harnessing Twins/Threads to Increase Aircraft Availability
For GE Aviation, the true power of digital twinning/threading lies in its ability to improve the management and maintenance of components, aircraft, and fleets, all with the common goal of increasing their reliability. This approach should ensure that aircraft are available more often, while unpredicted maintenance events and their consequences are reduced.
“Digital twins enable us to exercise and understand the behavior of an asset in states/situations likely to be encountered in its lifecycle,” said Dinakar Deshmukh, GE Aviation’s vice president of Data and Analytics. This intelligence is then used by GE Aviation to maximize the performance and reliability of an asset in-service, optimize asset/component in-service life and maintenance, and forecast/balance shop visits for overhauls while optimizing repair/overall workscopes.
Overall, “GE Aviation is using these technologies to invest in improving the accuracy of our Off-Wing/In-Shop analytics,” said Deshmukh. “We are continuing to monitor our deployed digital twins, and are embedding advanced machine learning techniques to adjust/adapt the analytics automatically, using statistical and reinforcement learning methods.”
A case in point: GE Aviation’s Analytics Based Maintenance (ABM) software collects sensor data from physical engines and inputs it into their digital twins to better predict unscheduled maintenance issues before they occur.
“Unscheduled engine removal (UER) and in-flight shutdown (IFSD) of engines are one of the drivers of delays and cancellations,” Deshmukh told ATR. “While delays and cancellations adversely impact profitability, having engines running longer on aircraft improves profitability. Operators expect to maximize ‘Time on Wing’ (TOW) and have predictable engine removals for service (to avoid UER). GE has made this expectation a reality for some of their customers through ABM. In ABM, digital twins of key engine parts have been developed, and these individual twins are aggregated to ‘predict’, well in advance, the likelihood of engine removal.”
The power of the ABM approach speaks for itself. “By using digital twinning, GE Aviation has been able to improve the overall efficiency of engine monitoring by double digit percentage improvements in coverage, lead time and false positives,” said Deshmukh. “One of our customers has acknowledged that ABM has improved their TOW by 20%, and reduced their UER by one-third.”
IFS Boosting Aircraft Uptime
Enterprise software developer IFS takes a Big Picture view of digital twinning/threading. “Digital twins, alongside AI (artificial intelligence), IoT (Internet of Things) and more, is all about gathering key data insights into a digital thread that will enable predictive maintenance to make even greater strides in the coming years,” said James Elliott, IFS’ principal bbusiness architect of Aerospace & Defense. “For example, as of 2020, Rolls-Royce — supported by IFS — is using AI forecasting to help airline customers automatically update predicted maintenance deadlines for every life-limited component inside their engines. This is a key part of the Rolls-Royce Blue Data Thread strategy, a digital information thread connecting every Rolls-Royce powered aircraft, airline operation, maintenance shop, and factory.”
IFS has also been assisting in the development of Rolls-Royce’s IntelligentEngine concept, “a form of cyber-physical service where the physical engine, the services that surround that digital engine and Rolls-Royce’s digital capability are indivisible,” Elliott said. In the IntelligentEngine universe, a physical Rolls-Royce engine is in constant contact with its digital twin, updating it with data about the physical engine’s operating conditions and flying environment. This provides operators with the data they need to make smart decisions to maximise aircraft availability, while minimising engine maintenance costs and flight disruptions.
“By mapping the data on how an airline expects to fly a particular engine and combining it with the airline’s specific data on expected part life and so forth, IFS can use this technology to provide companies with accurate predictive maintenance deadlines right down to individual part and serial numbers,” said Elliott. “The stats tell the story: Data from IFS aviation customers over the last five years shows that 45 percent of all airline parts removals were unexpected, so the industry is in serious need of more intelligent predictions for maintenance on AOG faults, remaining operating life and repetitive defects.” Based on IFS’ own data, migrating engine maintenance to AI-based aircraft analytics such as digital twins can lead to a 30 percent increase in aircraft uptime.
Lufthansa Technik’s AVIATAR Delivering Solid Results
ATR’s 2019 Twinning article spotlighted Lufthansa Technik’s (LHT) AVIATAR platform as a digital twins pioneer. “We launched AVIATAR in 2017 as the independent platform for digital products and services developed by Lufthansa Technik and as the digital twin of aircraft fleets,” said Peter Isendahl, LHT’s senior customer success manager of Digital Fleet Services. “AVIATAR combines fleet management solutions, data science and engineering expertise to provide a comprehensive range of integrated digital services, applications and products for airlines, MRO companies, OEMs and lessors that seamlessly integrate with physical requirements in TechOps and beyond.”
Four years later, AVIATAR’s suite of 50-plus predictors are delivering value for its users. “For instance, the IDG (Integrated Drive Generator) Predictor avoids up to 30 percent of unscheduled removals for some airlines and could generate several hundred thousands of Euros saved each year for a fleet of 100 A320s,” Isendahl said. “Meanwhile, the digital AVIATAR Technical Logbook reduces manual efforts by up to 80 percent compared to a paper logbook and reduces the defect closing time by 50 percent on average, which improves turnaround time and maintenance efficiency.”
AVIATOR doesn’t just use digital twins and other advanced digital tools to alert customers to possible problems before they occur. The system offers technical solutions to address these problems as well.
In addition, “AVIATAR’s ability to interface and combine this data with other digital solutions — such as Maintenance & Engineering systems like AMOS or TRAX or ERP systems like SAP — allows our customers to create a single source ‘digital truth’ network of systems,” said Isendahl. “Digital Threading is a key element in this context and already in operation at Lufthansa Technik with AVIATAR.” Recent signups to LHT’s AVIATAR program include United Airlines and Sichuan Airlines.
Siemens Committed to Digital Twins/Threads
Siemens has fully embraced the concepts of digital twinning/threading and made them integral to Siemens Digital Industries Software’s Xcelerator portfolio.
“Xcelerator provides solutions across the full product lifecycle, from the earliest concept design through certification and into production and maintenance operations,” said Dale Tutt. “It provides the most comprehensive digital twin for the product, production process and maintenance operations, connected by digital threading in a flexible and open ecosystem that provides seamless transitions and traceability across the full lifecycle from engineering to production and maintenance.”
“Aerospace companies that are embracing the digital twin and thread are seeing transformational business results,” Tutt added. “They are developing new products faster, improving production line quality while reducing the time and cost to build aircraft, and reducing the time required to maintain aircraft.”
Based on Siemens’ own data, aerospace companies who are using digital twinning/threading are achieving an improved first pass yield of 75 percent for engineering designs, resulting in fewer design revisions. At the same time, these companies are able to reduce physical test programs up to 25 percent by using virtual testing.
Other advances driven by twinning/threading include improved engineering productivity due to 60 percent fewer hours being spent on projects “by using the digital twin and thread to minimize data management and automate updates for design changes,” said Tutt. This process also leads to a 50 percent reduction in assembly hours on manufacturing lines — with a 90 percent reduction in change orders and quality issues — and a 25 percent reduction in scheduled maintenance hours through optimization of maintenance processes.
Advances to Come
It is clear that digital twinning/threading is already providing substantial benefits to the aerospace industry, from component manufacturers and OEMs to operators and their MROs. But according to the companies we spoke with, the future promises bigger and bolder advances. Here are some of their predictions, again on a company-by-company basis.
Let’s start with Boeing: “As we continue to develop and enhance our analytics capabilities, we anticipate integrated products that support airline operators,” said Darren Macer. “By integrating the various applications airline engineers or crew use to complete their daily tasks, we can deliver efficiency and analyze local data to derive insights in real-time. This will move prediction models beyond day-of operations to weeks or months in advance.”
With digital twins constantly monitoring and mirroring the performance of physical aircraft systems, operators will be able to predict and prevent a far larger range of issues before they occur. This will result in significantly enhanced uptimes and aircraft availability.
“Already, digital twin technology bolstered by AI and machine learning tools is enabling us to offer more prescriptive maintenance,” Macer said. “This prescriptive maintenance goes beyond individual recommendations to enable all the maintenance necessary to maintain operations from predicting and identifying parts to replace (as Airplane Health Management already does today), to automatically updating maintenance task cards, notifying the technicians, and automating requests to order the parts ahead of the next landing.”
The best part: “These preventative maintenance diagnoses can take place while the plane is still in the air to ensure everything is ready to go for the maintenance crews before it even lands,” he told ATR. “We are already seeing scenarios like this happen with the technologies we have available today, and this will continue to improve as we incorporate newer technologies into airplane maintenance applications for airlines.”
At GE Aviation, Dinakar Deshmukh foresees a number of exciting applications for digital twinning/threading. They include deploying more Near-Wing and On-Wing monitoring/predictive solutions to improve aircraft availability, and using AI-enabled systems to “learn” from new data as it comes into digital twins. “These technologies also create new datastreams and metadata, which can be further leveraged in future to build advanced AI solutions forming a close loop cycle,” he said.
Citing Rolls-Royce’s Blue Data Thread as “a prime example of how technology is transforming aviation,” IFS’ James Elliott underscores the benefits delivered by this OEM’s digital twinning/threading approach. “By providing a digital backbone it not only allows exchange of critical engine health and maintenance information, but also provides the analytical insights to truly realise the potential of predictive maintenance,” he said. “This translates into daily improvements, significantly less unexpected failures and maximum possible time on wing.”
“As the aviation industry moves towards a greener future, digitalization and predictive maintenance will play an important part,” continued Elliott. “For Rolls-Royce, the Blue Data Thread programme aligns perfectly with these priorities. By reducing the need for maintenance interventions, part replacements and overhauls, manufacturing use of energy and resources is reduced, and the emissions footprint of part and engine logistics is minimized.”
For LHT’s Peter Isendahl, digital twinning/threading is not only a growing trend in aviation, but an absolute necessity for MROs to effectively support the world’s expanding aircraft fleets. “Nothing is changing the MRO industry and is driving the development of new solutions more than digitalization,” he said. “It is the only game changer of this decade. With 50 times more data being generated by new aircraft types and approximately 50 percent of airline operating costs consisting directly or indirectly of MRO services, further cost reduction can only be accomplished through MRO and operational optimizations. Before the next generation of aircraft technology after 2030, no major other cost savings potentials are to be expected.”
“We are in the midst of a very exciting transformation, as we partner with companies that are obtaining significant reductions in manufacturing time by 50 percent through digitalization, and seeing similar results with maintenance operations,” concluded Siemens’ Dale Tutt. “This transformation will continue to grow in coming years as more companies and suppliers adopt digitalization.”
In 2019, ATR’s Twinning article introduced many readers to the concept of digital twins and digital threads. Two years later, this update shows how much progress has been made since that article was published. And by 2023? Given the clear economic, operational and safety advantages offered by this approach, it won’t be surprising if digital twinning/threading has become an integral aerospace industry practice by that point in time, like Lean Management and Just-in-Time Delivery did in previous years. Check this space in two years to find out! THE LATEST ON VIRTUAL MODELS