Aerospace & Defence

De-risking electrical compliance in the aerospace industry

6th June 2019
Joe Bush


Tony Nicoli, Aerospace & Defence Director, Mentor’s Integrated Electrical Systems Division, speaks to Electronic Specifier about the company’s new automated design-for-compliance methodology that will impact the aerospace industry.

Today’s modern aircraft systems, such as electrical flight control systems and in-flight entertainment systems, require more power, have more electrical content, and have higher compliance risk than ever before due to increased complexity.

The aircraft wire and cable market is expected to exceed more than $1bn by 2024 at a CAGR of six percent according to a recent study by Market Research Engine conducted earlier this year. However, current methods for verification and analysis of that market rely on fragmented data, typically conducted manually using drawings and spreadsheets (crucially after the major electrical design work is complete).

Uncovering problems at this late phase forces costly design iterations and missed critical milestones, thus impacting aircraft revenue. 

“OEMs increasingly need to differentiate their aircraft,” said Nicoli, “and increasingly this is done by increasing functionality. This in turn is done electrically because the OEMs get more bang for their buck by implementing additional functions electrically than they would with a mechanical, pneumatic, or hydraulic system - things like WiFi and video streaming. Also electrical systems are more maintainable, more reliable, use less energy and weigh less. And just like in our cars, electrical hybridisation is pervasive in aircraft.”

An electrifying industry
As such this aircraft differentiation has led to an enormous growth in electrification. The amount of electrical power generation in aircraft has gone up by a factor of ten over the last 50 years. However, more than that, looking at just the last 20 years, it has exploded with the advent of the Airbus A330, the A380 and the Boeing 787 - the latter can actually generate enough electrical power at full capacity to power 500 average houses. 

“It’s a power plant unto itself - it has four generators, two APUs (auxiliary power unit) and that has a huge impact on the electrical system,” added Nicoli. 

Electrification of aircraft

Above: Electrical power generationn in aircraft

This increase in complexity has led to an increase in content on aircraft’s EWIS (electrical wiring interconnect system). Nicoli explained that three percent of a modern aircraft’s weight is represented by its wiring, and the costs of that are increasing as we move towards much more sophisticated levels of data being communicated across the EWIS.

So over the course of the last 20 years the electrical content in aircraft has gone up, power demands have increased, and therefore it has become more and more of a challenge to manage. 

“Some EWIS’s are around 60ft long and 700lb. That is not something that can be moved by an individual,” added Nicoli. “So these types of systems need sophisticated design approaches that not only provide functionality, ensure safety and minimise cost and weight, but they also need to be designed in a way that they can be assembled and installed in an efficient way.”

In a typical commercial aircraft there could be around 500km of cabling; 100,000 wires; 7,000kg worth of wire weight; and 40,000 connectors. Because of this the process of designing the systems, integrating and installing them has become riskier. 

Nicoli explained: “I’ve been told by industry experts that when you perform any sort of design integration in the aerospace industry there will always be issues that crop up that you didn’t expect or anticipate, due the way that the capabilities of aircraft are stretched to increase performance. 

“Traditionally, the industry has found ways to address issues relating to mechanical, pneumatic, and hydraulic implementations. However, electrical systems don’t have that level of maturity. So when an electrical problem hits, it hits hard, and usually forces a very significant redesign, re-qualification, recertification and re-integration, and this can last for over a year and cost over $1bn. So these sort of electrical design iterations not only put the programs and the peoples’ reputations at risk, it can jeopardise the entire organisation.”

Timescales are tight in the aerospace sector and as such, personnel working on many aircraft development programmes will try to get ahead of schedule to gain an advantage in order to achieve early entry into service (EIS), as it’s not until the aircraft reaches this stage that it starts to achieve revenue. 

Therefore, it is not unusual for an aircraft to be built ahead of integration milestones in an attempt to get to the EIS quicker. However, this is fraught with danger in the complex make-up of the modern day aircraft, as Nicoli explained: “We had a customer that built six aircraft using this modus operandi. However, it was only after construction was complete that they discovered they’d missed a redundant system, which meant they couldn’t even fly. 

“This resulted in them going back and conducting a complete redesign; requalification; retest of all the electrical systems; reintegration; then they had to rip everything out of those six aircraft and rebuild and reinstall them. That took them almost two years at a cost of $1.5bn.” 

The solution
To mitigate risks such as these, Mentor, a Siemens business, has announced its new Capital software product which helps simplify aircraft electrical design compliance and certification.

Nicole added that this is the first electrical systems technology that leverages automation and digital data continuity to facilitate regulatory compliance using a digital twin to predict the aircraft’s electrical power demand.

“There are real advantages of our new Capital Load Analyser,” added Nicoli. “It will enable you, via the digital model, to conduct tasks like compliance analysis and do it consistently, and electrical load analysis at the platform level, which ensures that power management is done properly for safe and functional flight, for all flight phases and in all conditions - even emergencies.” 

Commenting on the expensive case example, Nicoli added: “If they had some of the capabilities that we’re introducing then that costly iteration could have been avoided entirely. They could have had the designer guided by a tool like Capital to highlight that particular problem. They’re not stupid. It’s the complexity that made this example difficult. They missed something because there’s just so much to do. Compliance is one of the key milestones to reach on the journey towards EIS, and often issues are found at this stage.”

Nicoli explained that not only is compliance complex, it represents the intersection between that modern system complexity and the old methods of performing the analysis. Therefore, demonstrating compliance has become increasingly difficult as the level of complexity has increased. 

He added: “Methods were developed decades ago in an era of far simpler electrical systems; and these methods are onerous and expensive due to manual processes and disconnected data sources, and as such, are extremely time consuming. In addition, it’s often not until the end of the program that compliance issues are found, forcing an expensive design iteration at a critical program phase.” 

One of the most important elements of compliance is electrical load analysis due to its close links with safety. It’s the checks that ensure all the electrical systems work in all flight phases and all conditions. However, analysing that power can present challenges.

Nicoli continued: “When we spoke to customers an issue they had in achieving effective power analysis was that they didn’t know if they were analysing current data, so they didn’t have a way of controlling the configuration and analysis of their designs. Things would change from under them, and they would find issues in peer review because of changes they were unaware of that occurred earlier in the process.”

In addition, from aircraft serial number to serial number, the electrical distribution system changes by around 30%. This is because of different configurations for different operators - Lufthansa asks for different requirements from the manufacturer than American Airlines for example. 

Also, the aircraft are not purchased over a short period of time. “The end customers don’t have the money to buy them all in a month, and the manufacturers wouldn’t be able to produce them that fast anyway,” added Nicoli. “They don’t buy them in a year either, they buy them over the course of five to ten years. During that time the OEMs find new ways of making the electrical system, new ways of implementing the functionality that the customer wants, and they will also be required to make changes in line with new regulations and the electrical systems have to be adapted as a consequence. In short, no single aircraft is the same.”

Another issue for customers is evidence generation. Customers spend weeks generating evidence reports, then something changes in the production cycle which means they have to start again. At present there’s no efficient way of bringing the analytical data into the publications teams who can then produce documentation that the regulators look at. 

“The reason for this is because the tools being used are disconnected,” added Nicoli. “They’re using ExCel and Word, plus legacy systems that were developed in the 1970s and some even earlier. They are used because the teams are familiar with them and it’s what they’re used to, however they have issues; the main one being that they are not robust to complexity or scaling to the size of the electrical systems we have today.

“Our vision is to use digital technology to reduce program risk and to improve our customers’ business processes. We call it ‘implementing the electrical modal-based enterprise’ where multiple engineering domains collaborate together, all the way from systems engineering and design through to manufacturing and sustainability.”

Nicoli added that this vision is built upon the idea of data coherency; architecture for integration and advanced automation. Data coherency is really all about the digital twin or digital thread - being able to share data innately across the tools that provide you with the ability to perform different tasks across the development lifecycle. 

Nicoli continued: “Once you have that, combined with the architecture for integration, you can automate processes to guide people interactively; build algorithms to ease work burdens; and build verification and checking into the environment so that you are aware of the requirements - both functional and regulatory - that you are trying to achieve.”

Mentor’s new tool, called Capital Load Analyser, performs electrical load analysis, which aims to accelerate aircraft certification by de-risking the environment around certification and acceptance milestones.

Nicoli added: “We’ve built our Load Analyser in conformance with MIL-E-7016F and we are also developing a Wire Derating Analyser and a 3D Signal Separation Visualisation and Checking Analyser, the former of which is in conformance with MIL-W-5088L.” The latter two products are expected later this year.

The aim of these offerings is to help aerospace developers exploit the digital twin of their product, which is then applied in the analysis environment to create a digital twin of flight performance. “We’re creating a way of verifying things accurately in a way that is scalable, automated and continuous,” said Nicoli.

“By putting this sort of analysis at the touch of a button, it reduces the time taken for verification, and you can check how your changes are impacting the electrical load and power management every time you make an iteration, in real-time - you don’t have to wait until the end. So you can check, analyse and virtually verify, as you design. So instead of finding out that you have a redundancy or load management problem during integration, you find out about it at the design stage, which enables you to avoid that costly problem which can potentially cause a $1bn impact on your programme.”

Nicoli added that the importance of reporting and evidence generation in the aerospace sector should not be underestimated. In the US, the FAA actually holds the officer who signs that compliance form, personally liable if they approve something that then fails. Therefore, they need to understand that the power management has been done appropriately and safely. 

“This needs to be in a format that they can assimilate,” Nicoli added. “The issue is that the different aerospace organisations from various countries have different report formats, different ways that they want to view the data, their offices have different requirements and individuals have differing methods of assimilating information.”

As such this proliferates the kind of reports that have to be created, shedding some light on why the compliance process can take such a long time. Nicoli added: “What we’ve done is integrate the ability to create a library of report templates into Capital and we’ve incorporated the capability to map the analysis results directly into the report. So literally, as the analysis changes, you can hit a button and populate a whole host of reports that you can provide to the people who you work with on a regular basis.”

This is just one function of Capital that has been particularly well received by Mentor’s client base. Reporting is something that they don’t want to be doing. “They want to be building new innovative platforms, not reporting on them. So they see this as a huge bonus in terms of their own personal working environment and to reduce the risk and time of reaching the compliance milestones,” Nicoli concluded.

“In summary we are applying modern methods to meet the complexity challenge in modern aircraft, so that you can reduce your program risk, avoid iterations and get to electrical compliance.”

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