How is BizJet Engine Maintenance Evolving?

Engine maintenance has evolved significantly in recent years, with sensor improvements and advances in analytics supporting a continuous, real-time approach. Industry specialists believe these advances will underpin an increasingly predictive service in the years ahead.

Jet Support Services Inc (JSSI) provides a range of maintenance, repair and overhaul (MRO) services for business jet operators, with engines a significant focus for the company – including routine inspections, engine overhauls and other services.

According to Timothy Ferrell, the company’s vice president of technical services, there have been significant diagnostic improvements in both aircraft and their engines, with MRO providers able to monitor faults and proactively replace failing components.

Maintenance facilities have embraced modern technologies, Ferrell says. Digital technical manuals – often accessible via mobile devices – allow for easier management of information. Specific shops have pre-determined parts requirements that can be accessed through project management software, which is delivered to the workstation “without inefficient trips to the parts room,” he adds.

Faster Data, More Efficiency

The increased availability of data is key to improvements in engine maintenance today. Historically, operators and MRO providers relied on manual data transmission, notes Axel Vöge, head of digital operations – Germany, Rolls-Royce. While this once involved the use of paper documents filled with data points, in more recent years it has involved emails being sent over certain periods (for example, monthly).

However, this could mean that by the time the company receives the data, inputs it into its models, and analyses it, the aircraft could have undertaken another 20 flights or more. “So you could only pick up slow trends – if there was some fast-moving development, you would miss it,” Vöge notes.

It’s therefore preferable to receive data immediately after each flight, or even during a flight, through an automatic transmission capability. This is also less labor-intensive for customers, according to Vöge.

The nature of automatic transmission depends on the age of the engine and the aircraft, he explains. 

For older systems, Rolls-Royce has retrofit programs where it can add additional equipment and make software changes to the airplane, enabling a data “snapshot” – a picture of the data set at one point in time, which can be compared with an earlier snapshot to detect any changes.

As an example, one snapshot could be from take-off, and another while the aircraft is in flight. With more modern aircraft and engines, however, the company is pursuing continuous data recording, where the data is transmitted constantly. 

This has progressed furthest with the company’s latest Business Aviation engines – its Pearl engine family – which include an engine vibration and health monitoring system that delivers a step-change to “on-wing” engine intelligence and supports continuous data recording, Vöge says.

The aim is to provide instant access to thousands of engine performance and health parameters with high levels of data quality, Vöge adds. The company can ‘talk’ directly to the engine health monitoring system, allowing the MRO team to ask the system to focus on different data points, for example.

Greater Number of Sensors

A spokesperson for General Electric (GE) said the company has made several changes to its maintenance programs in recent years, including through its OnPoint service, which is targeted at business jets.

The company has changed the way it prepares its newest engines, such as the Passport, which powers the Bombardier Global 7500. For this system, GE established a 12-member support team that worked over three years on both the engine and flight test programs, with the aim of involving field support engineers and the product support team more directly with the evolving project.

These advances are supported by improvements to the engines themselves. The GE spokesperson said the Passport systems have a greater number of sensors than previous versions.

This allows GE to use a digital twin – a computer-based model of a particular engine, which can be updated as new information is available, “giving owners and operators more data about their engine and its condition to plan maintenance”.

A More Continuous Inspection Approach

Modern engines are more reliable than earlier systems, with longer operational lives, according Andy Robinson, Rolls-Royce’s senior vice president for customers and services – Business Aviation. However, customers also “want them to go faster, be lighter and burn less fuel… there’s a balance between what you can do in terms of time on-wing and performance”, he notes.

Ferrell said the more modern engines have numerous sensors and signals that collect critical data from each flight, with companies like JSSI “better than ever at predicting component failure”. However, he said it is not a case of less maintenance being conducted today – rather, it is a more continuous inspection approach.

Additionally, “more complex systems and the use of exotic materials have driven significant increases in engine maintenance costs,” Ferrell notes, adding that real-time monitoring will transform engine maintenance, with systems that analyze and wirelessly transmit data during or immediately following flight.

This abundance of data will allow OEMs to evaluate reliability trends, driving maintenance schedule enhancements and eliminating unnecessary maintenance tasks.

Helping Define Optimum Inspection Intervals

The GE spokesperson said that data analytics can now be used to define the optimum inspection intervals for specific engines, reducing interruptions and minimizing unnecessary inspections. 

GE also offers a turn-key wireless data solution called Prognostic Health Management + (PHM+) that can be installed and tested in just hours, according to the company. PHM+ delivers alerts about future events, providing faster, more accurate engine field problem resolution.

Predictive maintenance has enabled Pratt & Whitney to move its customers’ engines to a more fully planned maintenance environment, according to a spokesperson for the manufacturer.

The company has worked to synthesize digital engine health management and build a proactive approach, through offerings like its FAST solution which provides advanced monitoring systems for a range of engines (including many of those typically used to power business jets).

Pratt & Whitney has worked to embed such technologies into its broader plans, like its Fleet Management Program (for fleets of six or more aircraft) or the Eagle Service Plan for individual airplanes.

The spokesperson highlighted the maintenance benefits of advances in modern engines, saying “there is no question that our newer engines were designed and manufactured with much lighter maintenance requirements”.

As an example, the PW800 engine used on Gulfstream’s G500 and G600 reduces required maintenance time in a number of areas. Additionally, the company’s new PT6 E-series engine monitors over 100 parameters for predictive analysis and maintenance planning, leading to more flight time, a doubling of maintenance intervals to 600 hours (compared with the PT6A-67P), and other improvements.

Machine Learning & Artificial Intelligence

Vöge says Rolls-Royce has developed a tool called Engine Network as part of its IntelligentEngine concept. This utilizes machine learning and artificial intelligence (AI) algorithms to analyse the data that the engines produce.

The tool enables the company to identify trends across whole classes of engines, he says, such as the context to a particular failure. “This means that we can identify engines that show similar behavior as other sets of engines in the past, and can proactively take actions before it can lead to problematic situations.”

The key data used in maintenance is the health information on the engine. However, there are additional data sets that are also essential, Vöge added, such as environmental information, which can also play a role in assessing the performance of a system. The aim is to use different sources of information to analyse performance at a deeper level.

“This helps us understand how the engine is performing, how the engine is being maintained, and how the engine is flying in its environment,” Vöge concludes. “When we understand how a specific, single engine is operating, we can learn how the entire fleet is performing.”

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