"Hey! This is Your Airplane Talking to You!"

Sept. 16, 2013
Innovative aircraft health monitoring (AHM) systems have taken the aircraft from an inanimate, reactively maintained object to become a fully-fledged flying CPU delivering detailed data to drive predictive, customized maintenance.

It used to be that when something wasn’t working quite right on an airplane, the technician would open up the area, look in and find the part they thought was causing the trouble, replace the part, and send the aircraft back on its way. Savvy troubleshooters knew what they were looking for and the general performance diameters (cycles or life averages) causing the components to be removed and replaced were based on generic data.

Many of today’s new aircraft fly with a central server on board, gathering data about the performance of various components on the plane, and putting together an interesting story for the ground engineers and OEMs to proactively and quickly troubleshoot before an event happens that could take that aircraft out of service.

While heavy maintenance per se will not likely go the way of the dodo bird, it is generally accepted in the industry that its footprint and type of maintenance performed during those checks is dramatically changing. Having all the performance data about a particular aircraft prior to planned downtime allows the operator to customize the check contents specifically to that tail number.

“We have a program ready which enables us to make the dynamic planning with the individual check content,” says Sebastian GIljohan, teamleader innovation at Lufthansa Technik. “But this needs regulatory agency approval, so this may take a bit longer to realize” as a shift in the way we’re working.

Both Boeing and many airline operators see this as an opportunity for industry members to lobby the respective agencies and OEMs to adjust their performance criteria thresholds from theoretical averages or generic hours/cycles to actual conditioned based maintenance based on all the data being generated.

“FARs lack the technological advances available in 2013. They contain limitations and theoretical development from the 1960s,” points out Frank Stevens, director of engineering at Republic Airways Holdings. “As an industry, we, (the operators), have to push this type of technology and say, “These advances are good for the industry and the public. Our regulators need to champion the efforts to provide updated regulations allowing operators and OEMs to take full advantage of new technology. The technology helps us make safer and smarter decisions. Lets learn from this and advance our maintenance programs.”

Helpful innovation

“Aircraft health management was driven initially for the customer benefit,” says Linda Hapgood, program manager for Airplane Health Solutions, Boeing Commercial Aviation Services. “They helped us design the system to help them minimize their operational costs and manage unscheduled maintenance.” AHM started with enabling the aircraft to be the CPU and being able to have a real-time picture of how the systems were working while making real-time adjustments.

While technology exists that allows maintenance troubleshooting traditionally performed onboard the flight deck to be performed now from quite a remote distance, for safety and regulatory reasons, the majority of the troubleshooting is still done in the shadow of the aircraft. “If you’re opening and closing digital circuit breakers and performing BITE tests where you could be moving surfaces of the aircraft and you’re not right there,” to see it, Hapgood points out, “if someone gets in the way,” it could potentially be dangerous.

“While the vision of a remote mechanic is becoming realized through technology, we foresee the result as an acceleration of teaming the technician on the ground with a remote team in an operations center. This teaming via the use of real-time data and remote access to aircraft information will speed up the diagnosis and decisions that get the aircraft out of the gate and on its way.”

Most operators have installed WiFi at their gates to enable quick downloads of data, for regular diagnostic trend monitoring, when the aircraft is at an airport. However, there’s also the possibility to troubleshoot the data while the aircraft is in flight, for certain fault conditions. Cost and data throughput volume are the main inhibitors to a constant stream of all the data from the aircraft while in flight. And while there is the ability to actually ping the aircraft and ask for specific information during flight, it’s expensive and a data bottleneck. Once a cheaper communication path to the aircraft is established, all of the systems can send data as generated, including having a potential replacement of the flight data recorder.

At Republic Airways Holdings, they’re creating reports to identify and connect events. “We use tools to review aircraft data against pilot/maintenance reports to confirm failure modes and to proactively address issues not presenting themselves directly," states Stevens. "In many cases, a technician focuses on the fault and not the reason for the fault. We use system-based data to narrow our search of the cause. We ask ourselves 'what if the valve is doing exactly what it was supposed to do?' We use this to find the hidden failure before it repeats itself. The direct fault may not be flagging on the airplane, but by sifting through the data, they can establish a possible fault chain. Technicians should not stare at the component that’s failing, they need to find out what is telling the component to fail, and go there.”

While some may see it as looking for the needle in the haystack, the operators and OEMs have come together to sift out the noise and decide what data needs to be acted upon. Some operators have trained their front line and engineering staff to interpret the data, and others have hired specific people experienced in interpreting flight data, who know the aircraft well.

By maximizing and using the right data, the operator can see a significant decrease of their unplanned events. “With a proactive review, we see about a 20 percent reduction in repeat write-ups and ‘soon to fail’ events. We also believe, through a fully implemented AHM program, we can do a lot better," Stevens adds. 

Another benefit to all the data is the operators’ ability to back up their operations performance “stories” for removal reasons. In this case, when a repair station returns a component as “no fault found” or the OEM indicates that the component “can’t do that,” the operator has data to show the repair station the fault as it occurred.

Stevens says it’s been very beneficial to creating a more proactive, collaborative relationship with the OEMs, as well. “Every day I receive emails from vendors and OEMs such as Bombardier, Embraer, Honeywell, and Hamilton Sundstrand asking for the data to be downloaded and sent in for review. These OEM connections create a collaborative effort to rectify the situation or determine the root cause of the event.”

Unfortunately, not all components are yet able to transmit data, but many OEMs are working toward that goal, by requiring certain components to be able to "plug and play" interface with the onboard servers. Some components, however, may never have or need that capability. “There’s always a tradeoff [of cost vs. data need] when looking at what systems have the most impact,” Hapgood points out. “It’s not just carte blanche ‘let’s just increase the data available’,” because the data benefit may not always be there.

Data security

With all the data hacking threats one hears in the news these days, is the aircraft of the future being set up to be another target? “Flight controls and that type of software are completely separated from the performance data,” according to Hapgood. There are also a lot of regulatory and OEM requirements that are put in place and rigorously tested to ensure that hacking of the airplane doesn’t happen. “And from a maintenance point of view, any of the data that comes off the aircraft today and is put into a system, like the Boeing AHM, is closely guarded and not public information.”

Much of the data delivered from these aircraft can be entered into and utilized by operators’ existing maintenance systems. “You do have to think carefully how you design it and who has access,” says Hapgood. It’s not the intent to have multiple systems delivering and storing the data, as this convolutes the message. The systems offered are less complex and are intended to decrease the hands-on requirement to manage and integrate the data. 

Revisiting the HAL 9000

Dave Bowman: Hello, HAL. Do you read me, HAL[RD1] ? 

HAL: Affirmative, Dave. I read you. 
Dave Bowman: Open the pod bay doors, HAL. 
HAL: I'm sorry, Dave. I'm afraid I can't do that.” 

With the computers doing more and humans needing to do less onboard, some people are having flashbacks to this scene from “2001: A Space Odyssey,” where the HAL 9000 computer takes over control of the space station. While we’re not to that stage yet, many have a fear of automation. “I think people are encouraged about what the airplane can do, but are leery about letting it go,” Stevens ponders. “They’re still a little bit leery to say, OK, I have everybody’s lives in my hands, but if I’m not watching it, who is?”

Many aircraft, particularly in the military sector, have become so automation-integrated, that they are virtually impossible to fly without computer assistance. And that goes right down to the maintenance, as well. Not only has the Defense sector mandated condition-based maintenance on their new aircraft programs, they’re implementing sensors all over the aircraft, including structural monitoring devices.

“With the ability to send a low current through the airframe, it repeatedly measures the aircraft to determine how or when a crack, dent, or scratch happens and returns a signal to the computer with the location and extent of the damage," Stevens says. "I would love to see this type of technology in the civilian sector. There are many maintenance tasks that require five hours to open an area for a two-minute inspection task.”

While the aircraft of today have significantly changed in the past 10 to 20 years to assist the operator in predicting events, reducing downtime, and finding the true cause of a problem, many in the industry still see it as just a start. “Will the technician of the future wear Google Glasses or special contact lenses that help them see through the fuselage?” asks Boeing’s Hapgood.

In an upcoming issue we’ll explore this subject more in depth, including what the technicians of today and tomorrow need to successfully support these aircraft.

[RD1]Use this statement as a pull quote in this paragraph

Karen Berg is a 27-year veteran in the aviation industry, starting at Northwest Airlines in 1986 in successively challenging leadership positions before joining KLM Royal Dutch Airlines in Amsterdam, the Netherlands in 1999. Among her roles at KLM, Ms. Berg was the director of maintenance and modifications for the KLM fleet and more recently, the VP Sales North America for Air France Industries and KLM Engineering & Maintenance.