Beckhoff control technology supports test rigs for aerospace applications

Futura Systems, a UK-based engineering specialist in complex test and control systems, was tasked with developing a new suite of aerospace fuel pump test rigs for Eaton Aerospace. The brief was not simply to replicate existing systems, but to create a more flexible solution capable of supporting a wide range of pump types.

Rather than designing dedicated rigs for individual products, Futura developed a suite of general-purpose rigs capable of testing 23 different existing pump variants, with flexibility to add even more future products. This introduced significant mechanical and control challenges, as each pump had different physical characteristics, pipework configurations and connection requirements.

A unique project

"On a normal test rig, you might have the ability to test three, four or five units, maybe seven at most," explained Jon Allmark, managing director of Futura Systems. "Twenty-three plus future unknown products is a different kind of challenge. At that point, you can't treat it as a series of small adjustments. You have to design flexibility into the system from the very beginning."

The rigs simulate real flight operating conditions, including pressure, temperature, flow rate and fuel behaviour. Test tanks rotate during testing replicating demanding scenarios such as starvation and repriming caused by the banking of an aircraft.

Accommodating multiple pump designs required extensive modelling and iterative design work. Futura overlaid all different pump configurations to ensure each rig could support the required range, while also allowing for future variants.

"The customer wanted to avoid ending up with another set of dedicated rigs that only worked for a narrow group of products," added Allmark. "The aim was to deliver a test rig with ultimate flexibility and future proofing so future products could be easily integrated into the test platform with having to buy a whole new rig each time.

Because the rigs use aviation fuel as the test medium, the electrical and control systems had to meet hazardous-area requirements under the ATEX Directive. This meant designing instrumentation and circuits suitable for potentially explosive atmospheres, which added another layer of complexity to the project.

The way it has always been done

In hazardous-area fuel testing, much of the instrumentation must be intrinsically safe. In simple terms, this means the electrical circuit must be designed so that there is not enough energy present to create a spark.

The traditional approach is to use a control system or data acquisition system, then install separate intrinsic safety barriers between that system and the instrumentation in the hazardous area. Those barriers perform an essential safety function by limiting the energy that can reach field devices, but they also add hardware, wiring, panel space and installation effort.

Many aerospace test systems have been built around established control and data acquisition platforms for many years. In some cases, the technology was selected when fewer integrated alternatives were available and has remained the default approach because engineers know it works.

"Separate barriers are a well-understood way of doing things, so engineers are comfortable with them," said Allmark. "The main downside of this approach is unnecessary additional cost. You have the control or data acquisition hardware, then the additional cost of the barriers on top. If you can build that function into the I/O system, you start taking cost and complexity out of the project."

Building the barrier into the I/O

For the Futura test rigs, Beckhoff's ELX terminal range became central to simplifying the control architecture, removing the need for additional barriers. The ELX terminals provide intrinsically safe I/O for hazardous-area applications, integrating the barrier functionality into the I/O system itself.

"With the Beckhoff ELX terminals, the clever part is not that the safety requirement goes away," explained Adnan Khan, business development manager at Beckhoff UK. "You still have to design the system correctly for the hazardous area. The difference is that the barrier function is integrated into the terminal, so you are not adding a separate barrier for every signal in the same way."

For Futura, this had practical benefits across the rig design. Reducing the number of separate devices helped reduce wiring, simplify installation and reduce the amount of hardware required in the panel.

"That is where the saving starts to build," said Allmark. "If you take out a layer of separate barriers, you are not just removing boxes from a cabinet. You are reducing the number of things that need to be wired, checked and maintained. On a complex rig, that makes a real difference."

One control platform

Beckhoff supplied more than a single component for the application. The system brought together Beckhoff PLC technology, standard I/O, ATEX-rated I/O, EtherCAT communication and integrated safety functions within one platform.

In conventional hazardous-area systems, control, data acquisition, safety and intrinsically safe instrumentation can often become separate layers of hardware. Each layer adds integration work, wiring and potential duplication of signals.

With Beckhoff, Futura could combine standard automation functions and hazardous-area I/O within the same architecture. EtherCAT communication also supported the use of distributed I/O, helping to reduce the wiring burden across the rigs.

"The ELX terminals are a big part of the story, but the wider point is the platform," said Khan. "You can bring standard I/O, ATEX I/O, safety, measurement and control into the same Beckhoff architecture. For a test rig builder, that gives you a cleaner system to design, commission and support."

The integrated approach extended to safety. Instead of using a separate safety system, Futura implemented safety functions within the Beckhoff PLC architecture, reducing duplication and simplifying system design.

Built to adapt

The result is a flexible, compliant test rig platform capable of supporting a wide range of aerospace fuel pumps. Instead of relying on dedicated rigs, the customer now has a modular system that can adapt as requirements evolve.

"The modularity is important because these rigs are not just being built for one moment in time," said Allmark. "The customer can prepare a new unit on a spare skid, bring it in and connect it up much more easily. That gives them a test platform they can keep adapting as their products develop."

The project demonstrates how new technology can reduce complexity in demanding test applications while delivering flexibility and compliance. By combining PLC, standard I/O, intrinsically safe I/O, safety and communication within one platform, Beckhoff supported Futura in developing a future-ready solution for aerospace fuel pump testing.

"A lot of the time, people stay with the architecture they already know because it feels proven. The opportunity is showing that there is another way to meet the same hazardous-area requirements, but with fewer separate pieces in the system," Khan concluded.