28. August 2025From the road to the skies

For over a decade, Sonplas has supported the maintenance of fuel and hydraulic systems in the aviation industry with special-purpose machinery. Drawing on its extensive expertise from the automotive sector, the mechanical engineering company develops custom assembly and testing systems for safety-critical components—all from a single source. These solutions enable flexible testing of various pump types, along with precise control of pressure and flow.

“The aerospace industry uses fuel-carrying components that are similar to those found in the automotive sector,” says Matthias Kraml, Sales Engineer at Sonplas. The medium-sized special-purpose machine manufacturer based in Straubing, Bavaria, draws on nearly 30 years of experience in assembling and especially testing components used in injection systems for the automotive industry. These include valves, injectors, pressure regulators, manifolds, as well as injection and pre-supply pumps. Kraml explains, “In the aerospace industry, these components are simply much larger—which means higher pressures and greater flow rates.” Sonplas has successfully applied its extensive expertise to meet the demands of the aerospace sector. Since 2014, the specialists have been developing highly flexible system concepts for functional testing of components in the Maintenance, Repair, and Overhaul (MRO) sector—primarily for hydraulic and fuel systems.

Comprehensive testing capabilities under realistic conditions

The special-purpose machine manufacturer designs test systems for a wide range of fuel components—including pumps—and allows for variable testing and environmental conditions to enable realistic simulation. This setup allows for hydraulic measurement of flow, pressure, and leaks based on customer-specific requirements. Air and liquid testing can be integrated into a single system, with calibration cycles, blow-out, and flushing processes fully automated. Sonplas also offers jet test stands that measure the angle and width of the spray emerging from the fuel nozzle. Kraml notes, “We even have our own in-house development lab.” This is complemented by feasibility studies and product testing. “We measure injection rates and monitor temperature,” the sales engineer explains. Both functional and endurance testing can be performed—on individual components as well as complete systems. “We perform all tests and measurements according to customer-specific requirements—following what are known as CMM specifications,” says Kraml. CMM stands for Component Maintenance Manual.

Climate chambers play a critical role in aviation, helping ensure that components can withstand the extreme environmental conditions encountered during flight. “We’re able to simulate various environmental conditions, including temperature, humidity, and air pressure—and even incorporate vibration testing,” Kraml explains. How safe are components in potentially explosive environments—such as fuel tanks or during the handling of flammable liquids? This is another critical area tested by the experts at Sonplas. “We implement projects for potentially explosive environments and substances in compliance with the relevant standards and regulations, such as ATEX and IECEx,” explains Kraml. “What matters is not only having the technical expertise for execution but also providing guidance during the planning phase and support during operation.”

 

Driving project success

Sonplas has already successfully delivered several projects in the aviation industry. One example is the testing of the highly complex main fuel pump used in the engines of the Boeing 777. It weighs just under 30 kilograms and is significantly larger than a typical bus pump. “This is where our experience with pumps from other industries really comes into play,” says the sales engineer. For this project, a flow rate of 650 liters per minute (170 gallons per minute) was required. The customer brought this challenge to Sonplas. The testing process is fully automated, with only a few manual steps required. The system independently identifies the component and automatically adjusts it. All required test steps are then performed in accordance with the relevant specifications. “This test bench allows us to test up to 15 different engine models,” explains Kraml. Sonplas’ expertise is also in high demand for center and wing tank pumps. While the testing process is largely similar to that used for automotive fuel pumps, the flow rates—reaching up to 900 liters per minute—are on an entirely different scale.

 

 

Tailored system solutions

As a special-purpose machine manufacturer, Sonplas is able to respond flexibly to specific customer requirements and deliver highly customized solutions, which is a clear advantage over standardized mass-production suppliers.

“Typically, customers come to us with their components, and the testing procedures are usually defined by the manufacturers,” explains Kraml. “Our job is to translate these testing processes into technical solutions and simplify them through targeted automation.”

The system concepts are developed in close collaboration with the customer and precisely tailored to each specific application. Depending on the requirements, a complete pump can be analyzed on the test bench, individual components like pressure relief valves can be tested—or both can be done simultaneously. To make this possible, Sonplas can integrate multiple testing methods into a single system when needed. “We fully automate our systems for the high-volume automotive industry—and that expertise can, at least in part, be applied to the aviation sector as well,” says Kraml. “Such automation approaches are still relatively uncommon in that industry.” In addition to developing complete test benches, Sonplas also supports the optimization of existing systems.

 

From a single source

Sonplas offers both assembly and testing from a single source, seamlessly integrating both disciplines into its solutions. Customers benefit from a trusted network of carefully selected, reliable partners—while enjoying the convenience of a single point of contact. The experts integrate proven off-the-shelf components where appropriate—and rely on in-house developments when standard solutions reach their limits. This approach results in special-purpose machines that are highly adaptable, economically efficient, and functionally robust. We understand exactly what matters when it comes to these components,” says Sales Engineer Kraml. “That allows us to engage with our customers as equals—a clear added value.”

With its customized solutions, Sonplas has established a strong presence in demanding sectors such as the automotive and aerospace industries. The successful transfer of expertise from a highly industrialized field to a safety-critical sector demonstrates that Sonplas’ technological capabilities are scalable across industries. This positions Sonplas to tap into additional high-growth markets, including medical technology, semiconductor production, and energy engineering. “Our special-purpose machine approach clearly delivers value to the customer,” Kraml emphasizes.