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Central Maintenance Systems Evolving To Leverage Big Data

How central maintenance systems solutions are probing deeper into data rich resources.

Printed headline: Richer Data, Rising Opportunities


With each new generation of aircraft, the volume of data generated grows exponentially, leading to increasingly capable central maintenance systems (CMS) presenting more predictive and proactive maintenance opportunities. Opportunities to leverage condition-based maintenance on the new 777X, for example, will be five times what they are on the currently produced 777 family, according to Boeing.

“Lightweight systems that record data on a real-time basis are enabling faster and more flexible deployment of analytics onto the aircraft,” says Jon Dunsdon, chief technology officer at GE Digital Solutions. “This brings better analytics closer to the data and allows BIT [built-in test] reports to be fused with flight data, enabling the opportunity to learn from the rich data set that is collected.”

In that regard, GE Aviation Digital Solutions has incorporated analytics derived from artificial intelligence and machine learning (AI/ML) to “provide constantly improved diagnostics and early detections solutions,” he says. The CMS, Dunsdon points out, has evolved into an overall health management system, providing actionable insights for both operators and OEMs—along with the capability to communicate with the ground using a prioritized context and cost-aware management approach. “Where this technology approach has been employed for our engines, we have seen proven results with unscheduled engine removals reduced by up to 56% for some operators,” he says.


Boeing’s 777X jetliners, pictured being assembled, will incorporate central maintenance systems enabling opportunities to leverage condition-based maintenance as much as five times more than on Boeing’s current 777 family.

The OEM’s modeling approach, reports Dunsdon, enables health-aware components, subsystems and systems to report diagnostic results for themselves or for each other. For components that are not health-aware, their health status can be reported on their behalf by the CMS/OMS (onboard management system) products.

Dunsdon says that by being able to process full flight data using advanced AI/ML-based models, the technologies are able to more accurately isolate faults and better diagnose root causes of failures. “The combination of the onboard piece, right-time communications and a user-focused ground solution means that we can deliver triaged and actionable insights—rather than a cryptic set of fault codes—directly to the maintainer, who is actively trying to turn the aircraft for its next flight leg,” he says.

Christopher Thomson, vice president of sales and marketing for Curtiss-Wright, notes that the average age of a commercial airliner in service is now less than 15 years—and getting younger. A more youthful fleet means much more data is generated.

“Younger aircraft are recording more data parameters than ever before—now surpassing 100,000 parameters of data,” he says. “As the new generation of aircraft move from the drawing board to production, a next generation of central maintenance computers will evolve to acquire, store and analyze more data in an increasingly data-rich aircraft environment. This will be especially true as the industry trend toward performance-based data continues to move forward.”

But Thomson cautions that even with the technological advances in CMS, the aerospace industry has lagged behind with respect to the potential wealth of data that could be mined to ascertain system operational data and predict failure.

“While today’s jet engines are highly instrumented to acquire data regarding their maintenance and operational status, most aircraft systems have not been,” he notes. “This has become a big area of concentration at Curtiss-Wright. Our focus is on the ‘dark parts’—those with no or limited monitoring instrumentation, such as landing gear, flight control systems, hydraulics and fuel systems—and making their information available to the central maintenance computer.”

Along this line, reports Thomson, passenger air conditioning systems are presenting a significant opportunity for Curtiss-Wright, which two years ago applied a data acquisition component to the air conditioning on Boeing 737s operated by a major U.S. domestic carrier. Thomson could not disclose the airline’s name, citing confidentiality agreements, but adds that the passenger air conditioning systems generally appear to be among the most prone to failure.


Curtiss-Wright’s KAM-500 component is being retrofitted to a major U.S. airline’s Boeing 737 fleet to capture temperature and pressure data, via Boeing-supplied sensors, on the passenger cabin air conditioning systems.

Curtiss-Wright supplied the acquisition hardware to capture temperature and pressure data, while the airline and Boeing selected the number of sensors to be applied to the air-conditioning units, as well as their specific locations. The airline also developed the software algorithms and certified the system under its own supplemental type certification.

“The acquired data was fed to the aircraft’s central maintenance computer [CMC] with no changes required to its architecture,” Thomson notes. “What you have is information coming from another sensor that simply adds to the CMC’s existing data.”

Thomson says the airline has reported “seeing real benefits” in recent months and is continuing to upgrade its 737 fleet with the passenger air conditioning data acquisition system. “They also plan to install the system on new 737s upon delivery from Boeing,” he adds.

Stacy Morrissey, managing director of fleet engineering for American Airlines, says the new-technology CMS—installed on American’s Boeing 787-8s and -9s, 737-8 MAXs and Airbus A321neo aircraft—“function like a digital motion picture camera,” constantly acquiring data down to a more granular level in real time throughout the flight. In contrast, she points out, the CMS onboard the carrier’s older aircraft, such as the 767s, generate a snapshot of the aircraft’s condition at the beginning and end of the flight.

“American Airlines is in the process of deciding which fleets will be upgraded with some of the newer CMS options available from our vendors, which include Collins Aerospace and Teledyne [Technologies],” Morrissey notes. “Once the decision is made, we will retrofit with devices that will send out more aircraft condition data.” She also says a number of aftermarket options are available for CMS retrofit on older aircraft, including wireless data transmission and software for capturing additional data, both for older and newer aircraft. These options are all airline modifiable.

“The goal is to capture real-time data across the fleet, download it wirelessly and use that data predictively,” says Morrissey

“We have selected CMS with the capability to download more data and parameters, wirelessly, directly to a computer on the ground when the aircraft lands,” she adds. “This eliminates the time-consuming need for a mechanic to meet the aircraft, insert a card and download the data from the CMS computer, then go back to a facility and download the data from the card into another computer. With wireless transmission, the data is immediately available for predictive maintenance and also provides verification that a repaired component is functioning properly once

However, Morrissey points out, the full potential of the new CMS has yet to be realized. “They are an untapped resource at this time,” she says. “We are still on a learning curve.”

State-of-the-art CMS are not limited to commercial airliners. High-end business jets such as the Gulfstream G650 and G650ER have been fitted with a Honeywell CMC combined with an Aircraft Health and Trend Monitoring System (AHTMS) from GE. Colin Miller, Gulfstream Aerospace’s senior vice president for innovation, engineering and flight, says the CMC collects data contained within the jets’ PlaneView cockpit display suite. Additionally, the dedicated AHTMS culls data from a PlaneConnect HTM, which was initially introduced on those two aircraft.

PlaneConnect HTM constantly collects and transmits parametric data in real time directly to the operator and—at the operator’s discretion—to preselected reviewers, including Gulfstream’s Technical Operations. “The HTM works in the background and transmits the data to aircraft support on the ground, either by wireless network or cellular data transmission,” says Miller. “Using system features, technicians can run real-time data inquiries in-flight without having to interact with the flight crew.”

The HTM also sends time-stamped data to a website dedicated to that specific aircraft. The flight data is “prioritized and organized” and includes such aircraft performance data as fuel consumption, pressure readings and temperatures, along with aircraft operations data.

“The purpose of PlaneConnect HTM is to provide an enhanced awareness of the health of the aircraft during and after each flight. Taking this proactive approach reduces the required on-hand stock of parts [and] turns unscheduled events into scheduled events with minimal disruption to the owner’s flight schedule,”
says Miller.

PlaneConnect HTM on the G650ER and G650 interfaces with parts and components that the CMC did not interface with on earlier Gulfstream models. They include air data, engine parameters, flight surfaces and landing gear. These, says Miller, were selected in order to gain additional insight into critical systems. “We use a combination of the CMC and PlaneConnect HTM to drill down on subcomponents or parts on the G650 and G650ER. Examples are the air data probes on those aircraft. If we see a fault code or CAS [crew alerting system] message regarding a problem with the four air data probes, we can check the PlaneConnect HTM data to see if there’s a correlation.”

As a bottom line, the system provides “improved accuracy and reliability for maintenance in general,” Miller notes.

“We can use parameter information to identify when something is trending away from normal, such as an aircraft’s pitch angle, calibrated airspeed, or the time it takes to start an engine,” he says. “Then we can check across the fleet to see if that’s an area of concern or just an anomaly with one aircraft. The more information we are able to gather, process and analyze, the better we’re able to predict trends and their possible effects on reliability.” 

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