Reducing FMEA analysis time by 50 percent via modeling using mission-driven model-based systems engineering practices

Sustaining assets for the U.S. Air Force

Aircraft owners are increasingly prolonging the operational life of aircraft that remain relevant for today’s mission requirements. To keep the aircraft at a high level of operational performance over long periods requires systematic engineering, maintenance and supply chain programs. However, safety is also paramount. Although operators want to extend the life of their investment for as long as possible, their tolerance for safety risks are low.

This is where Skypath Analytics comes in. The company, based in Georgia, United States (U.S.), provides reliability, availability and maintainability analyses for aircraft systems and other critical assets. They also work with engineering, supply chain and maintenance, repair and overhaul (MRO) to help improve their processes by using the digital twin and simulation technologies.

One customer, the 448th Supply Chain Management Wing of the Air Force Sustainment Center, is responsible for sustaining the landing gear for all U.S. Air Force aircraft. To maintain system performance, it requires periodically updating the reliability, availability and maintainability analysis for these systems.

Skypath Analytics used the model-based reliability analysis tool, Maintenance Aware Design Ecosystem (MADE), to implement a new model-based systems engineering (MBSE) reliability analysis process for the KC-135, a Boeing 707 variant. MADE is part of the Simcenter™ software portfolio and integrates into Teamcenter® software, which are part of the Siemens Xcelerator business platform of software, hardware and services.

Double bogie main landing gear assembly on a KC-135.

Analyzing historical data

Landing gear is a safety critical system for any aircraft. One challenge is the landing gear and the electromechanical factors, including hydraulics, exposure to the elements. This increases the risk of corrosion, which can affect the structural integrity of the system; thus, requiring close monitoring and inspection.

Since the KC-135 is an older aircraft, the U.S. Air Force stores a large amount of its historical data and analysis in various legacy data systems, which are not well integrated. Therefore, the analysis involves analyzing various sets of siloed data, and then manually integrating them to see the entire picture. In this case, the digital thread is not connected digitally, so it requires a manual process.

James Hill, director of business development and operations at Skypath Analytics, explains that the first task was to analyze all the failures that occurred in the various landing gear subsystems across the fleet over the last decade.

“We imported all the raw data and generated a report of the drivers that cause maintenance work on the system,” says Hill. “We also analyzed which factors degraded aircraft availability, which could be reliability, maintainability or supply chain drivers. For instance, if a part that needed replacing wasn’t available.”

MADE model of the landing gear.

Aiming for accurate root cause analysis

Hill says that the aim of the reliability analysis was to do more than just look at issues with a particular subsystem. “Typical analysis identifies a failure of an isolated system, but a landing gear consists of many interconnected subsystems that can have an effect on each other,” says Hill. “This doesn’t tell you how issues affect adjacent subsystems. We wanted to look at it from an overall system perspective to show the bigger picture of why failures are happening and what the overall effect is. This helps with root cause analysis
rather than just looking at the symptoms of a failure.”

Skypath Analytics used MADE to create a model-based digital risk twin of the landing gear. Then they ran failure injections to compare the model’s top failure drivers with real-world data and identified discrepancies to investigate further.

“Rather than look at the top drivers of failure, we looked at each component’s actual performance relative to expected,” says Hill. “For instance, landing gear tires are designed to wear out after a certain amount of time. Using the MADE model helped us baseline the expected performance and analyze how the actual performance of a subsystem will affect the overall landing gear system reliability, which we couldn’t easily do with our previous analysis process.”

After identifying the top causes of failures, engineers ran a business case analysis on how best to mitigate them. This could involve redesigning a part, finding a new supplier, adjusting maintenance plans or other changes. They gave the customer the benefits of each, allowing them to make an informed decision on how best to proceed.

It was critical that the analysis and recommendations were accurate. If a root cause was misdiagnosed and the problem persisted, despite making changes, then they not only lost the money spent on the changes, but also the opportunity cost of not improving reliability and availability.

“We created a model of the landing gear that had all the failure modes for every subsystem,” says Hill. “This allowed us to generate failure diagrams and simulate those failures on the model and see how they affect the entire system, all with a click of a button. We then used the same model to carry out the cost benefit analysis of various corrective actions to give the customer an accurate picture of the options.”

MADE failure diagram.

Saving costs and time using MBSE

Hill explains the key factors in choosing the solution. “We needed a cost-efficient way to carry out the analysis, produce reports and provide ongoing support. MADE is designed to perform analysis at the full system level, using mission-driven MBSE methods, so it was the ideal solution.

“We pride ourselves on being a forward-thinking company, and MBSE is at the forefront of the latest developments in the industry. We work with customers who are also forward-thinking and want to take advantage of the latest technology. Although there was more of an upfront investment to build the model of the landing gear, we were confident it would lead to more efficient analysis and be an asset we could reuse going forward.”

In terms of savings, Hill is confident that the new solution made a significant difference, especially concerning failure modes and effects analysis (FMEA). “FMEA was the most costly and labor-intensive aspect of the project,” says Hill. “However, since this functionality is built into MADE, we could do this task in approximately 50 percent less time. Because the digital risk twin model built in MADE is a functional model and contains all the failure modes and effects, we created a dynamic FMEA model. Then, producing a report from that is an automated process. We have now replaced a static report with a dynamic model that we can leverage for a range of reliability and maintainability analysis tasks. This was great, not only for keeping costs down on this project, but also for enabling us to complete the work sooner and move on to other projects.”

KC-135 landing.

Integrating with Teamcenter

With MADE now a key component of Skypath Analytics’ toolset, Hill is looking to take advantage of its links with other software to connect the digital thread.

“Many of our customers use Teamcenter, so we’re looking to use the integration between this and MADE,” says Hill. “This will allow us to synchronize with the bill-of-materials and the rest of the digital sustainment thread to provide better traceability and streamline sustainment processes, reducing manual effort and improving efficiency. Then, if the design changes, we can run the reliability and cost benefit analysis in MADE and pass it back to Teamcenter to integrate into the digital sustainment thread.”

The Boeing KC-135 Stratotanker, a military aerial refueling tanker aircraft.