Condition-based maintenance (CBM) is an unremarkable name for an unremarkable concept—don’t fix what isn’t broken. But while this approach to equipment maintenance and sustainment sounds ordinary, it is having an extraordinary impact on improving the maintenance cost and readiness posture of military assets.
“Our cost-benefit analysis is showing about a $200 million cost avoidance for last year,” said Christopher Smith, director of the condition-based maintenance program at the Army Aviation and Missile Life Cycle Management Command (AMCOM), referencing fiscal year 2010. It has also “saved up to four aircraft and their crews where we’ve been able to detect a flight-critical failure before it has occurred,” Smith said.
Condition-based maintenance is the ultimate form of preventive maintenance. Using sophisticated sensors and data analysis, engineers can predict how long a piece of equipment or part will last, and schedule maintenance to take place at the optimal time, which is near the end of its life but before it fails. Sensors that measure vibration, temperature, pressure and other indicators are placed on crucial components of equipment, collecting performance data as the component operates. Those data points are collected and analyzed by engineers who can predict component failure and plan maintenance intervention.
Although in use in the private sector for a few decades, condition-based maintenance has only recently been embraced by the military sector. “CBM is a new mindset and a paradigm shift for the maintainers who do this on a daily basis,” said Deborah McLemore-Baugh, acting deputy director to Chistopher Smith. “We think CBM is a critical new tool for doing ultimately less maintenance because we are getting information ahead of time that allows us to be forward thinking. It is the new normal of maintenance.”
The Army aviation community was the first to adopt condition-based maintenance, partly because the consequences of equipment failure on an airplane can be catastrophic. Right now 65 percent of the aviation fleet is equipped for condition-based maintenance, and Smith expects AMCOM to be finished equipping the fleet by 2014.
“Our maintenance posture in aviation especially tends to be preventive maintenance focused. We don’t want stuff to break when we are out on a mission,” Smith said. “The consequences of unscheduled maintenance or failure can be fairly dire. Our goal was to find out how we could not do as much maintenance and still maintain the same level of readiness.”
Pinpointing the optimal time with an ever-improving degree of accuracy is the pinnacle of achievement in the field of condition-based maintenance, because it minimizes costs associated with maintenance and maximizes safety and readiness of equipment.
“We are two-thirds toward our ultimate goal: predicting with a high degree of accuracy when a system will fail,” said Dr. Abdel E. Bayoumi, director of the Condition Based Maintenance Center at the University of South Carolina, speaking about the progress the industry as a whole has made since condition-based maintenance was first researched in a laboratory setting. Bayoumi said that improvements in wireless remote sensing capabilities and computing power will help condition-based maintenance become more widely used by the military and industry.
“Any component has two points: the beginning and the end. It is easy to define those two points. The trick is to define where the system is right now and the ability to predict the remaining useful life of the component, subsystems or whole system,” said Bayoumi. Bayoumi’s research program began when the school was asked to help develop a cost-benefit analysis of the Army-developed Vibration Enhancement Management Program, a vibration monitor developed to help the South Carolina National Guard to help find a way to reduce vibration in its helicopters and predict the source of vibration. His program grew to include test facilities and equipment that allowed the center to accumulate data much more quickly, and gather more information about component performance.
Findings from the University of South Carolina research center make it quickly into the field. Last month, Bayoumi said, a maintenance process change was made because of research that found that helicopter hanger bearings could handle 3,500 flying hours of use and there was not need to overhaul them at 2,500 hours, as current practice dictated. Bayoumi expects this will save millions of dollars in terms of cost savings, maintenance time and availability of the helicopter.
Cost savings in replaced parts is another benefit of condition-based maintenance. AMCOM’s Smith said that they traditionally troubleshoot machinery in a linear fashion. “You start with part A, and then to part B, and so on until you find the problem,” Smith said. “But time is of the essence in combat and we don’t always have time to work our way to part F, the problem, by replacing parts A through E, which were in working order, by the way.” Condition-based maintenance allows part F, in this example, to be identified at the outset as the problem, saving time and unnecessary purchase of spare parts.
Universal Synaptics has another solution for this problem in electronics. Its intermittent fault detection and isolation system (IFDIS) is new test equipment that continuously and simultaneously monitors all circuit paths in complex electronic chassis so that intermittent failures can be detected and isolated to their precise locations. These intermittent or no fault found events can cost the military in excess of $2 billion annually, according to Universal Synaptics Vice President Ken Anderson, who explained that approximately half of all the line replaceable units (LRUs) and weapon replaceable assemblies (WRAs) that are returned to DoD repair depots do not have the problem identified and repaired. LRUs are modular components of airplanes or ships that are designed to be replaced quickly at a deployed location. When they fail in an operational environment, they can be immediately replaced and the old unit is sent back for reset.
“The classic repair sequence where a part within an LRU fails, the LRU is sent to the repair depot, the depot tests the LRU to identify the failed part, the failed part is replaced, and the LRU is returned to service, is only now working about half of the time,” said Anderson. “The other half of the time a part within the LRU has not failed, but rather there is something wrong in the chassis wiring that interconnects all the parts, such as a cracked solder joint, a broken wire, a loose wire wrap, a loose crimp connection, etc. The legacy testers at the repair depot were not designed to detect, and cannot detect, these intermittent wiring problems.” Therefore, Anderson said, the LRU is either returned to service without the problem being identified, located and repaired, or the LRU is determined to be irreparable.
These LRU and WRA components that have experienced intermittent faults during operation are sent to the field or flight line as fully operational equipment items, Anderson said. The IFDIS tests the LRU chassis wiring and identifies the location of each defect, enabling the chassis wiring problems to be repaired. Currently, an IFDIS tester is in use at Ogden Air Logistics Center, U.S. Air Force. Of the F-16 LRUs tested with IFDIS to date, 68 percent of all LRU chassis tested had one or more intermittent faults which had gone undetected with conventional test technology. Additionally, the IFDIS has recovered $36 million worth of flight assets previously considered “un-repairable,” eliminating the need for the government to issue new procurement contracts for similar equipment that will be riddled with the same failures.
The IFDIS was recognized as the winner of the “Great Ideas” competition at the DoD Maintenance Symposium 2010, and has been honored with a Tibbetts Award from the U.S. Small Business Administration for technology innovation excellence.
The ability to collect, store, correlate and move data is the limiting factor for condition-based maintenance in a deployed environment.
“Bandwidth is the primary distinction between a deployed and non-deployed environment. The data that we collect has to leave the deployed environment and come back to headquarters,” said Smith. “You can imagine the difficulty of moving a file. Some aircraft collect data at a rate of 50 megabytes per flying hour. You can imagine the difficulty of moving 50,000 megabytes from Kandahar, Afghanistan, to Redstone Arsenal through very thin bandwidth pipes.”
Additionally, the ability to analyze massive amounts of data in real time is a complex computing task, to say the least. Starview Technology, a nine-year-old semiconductor manufacturer, has developed a product that helps move the information generated for condition-based maintenance. Starview’s Smart Enterprise Platform enables businesses to improve operational efficiencies, minimize risk and immediately see the impact of any individual event across an enterprise, identify event patterns and trends that represent opportunities or threats, and then provide analysis needed to automate instant actions.
Steve Baunach, co-founder and chief technology officer of Starview Technology, said that their algorithms are designed to analyze moving data. “Our process pulls in data as it is happening to evaluate and make optimum decisions,” Baunach said. “Something just changed; what do I do?”
Starview developed the technology originally to help solve other manufacturing problems such as factory scheduling and machine calibration. Baunach said it has also been used to determine optimal throughput. But the technology is useful in other ways.
“What we’re doing is going horizontal. We believe the technology is applicable to multiple areas—monitoring residual gases at utility plants, for instance. From gas signatures, we can understand when transformers are going to fail,” Baunach said. “It looks at what’s going on in my infrastructure. And then computed the trend. Because we can look at large volume of data, can make correlations and conduct analysis of the trend line.”
Large manufacturing enterprises are similar to military environments, Baunach said, in that both require tight reign on logistics and usually involve the collection of data from many locations.
Industry has long recognized the multiple applications of condition-based maintenance—reduce unnecessary repairs, improve readiness, look for process efficiencies and higher performance. In recent years, the military has adopted what’s called condition-based maintenance plus (CBM+), which reflects some of the changes taking place in industry.
For the military, the “plus” designation encompasses equipment and maintenance process improvements that occur because of maintenance planning and technology development for capturing, storing, analyzing and communicating information. Changes in maintenance process and equipment are taking place because of this paradigm shift. Laptops and other portable computing devices are much more common now in a deployed environment for maintenance applications. With weapons systems and equipment available digitally, repair, replacement and part ordering can take place much more locally and immediately, reducing or eliminating the logistics tail that accompanies a deployed force.
All branches of the service are developing programs based on condition-based maintenance. The Army is branching into condition-based maintenance for land-based equipment. The Navy has launched its Integrated Condition Assessment System, which is an automated machinery condition monitoring and assessment tool. This system gathers and processes real-time equipment data from sensors and monitors. According to a 2011 Department of Defense briefing, the ICAS is installed on over 100 ships across 12 classes throughout the fleet and is considered integral to new construction and new ship design. The Marine Corps is using a program called Autonomic Logistics to implement CBM+ into its weapon systems. According to the 2011 briefing, the Marine Corps approach goes beyond conventional CBM to include monitoring other logistic functions such as fuel and ammunition levels. Air Force instructions and policy are being rewritten to incorporate CBM+ concepts and initiatives.
An unintended consequence of condition-based maintenance may be that operators and maintainers are less practiced in performing routine maintenance operations. Ngrain, a Vancouver-based modeling and simulation firm, has developed a 3-D virtual training environment specific to maintenance training and performance support that is currently deployed in Afghanistan.
Gabe Batstone, chief operating officer of Ngrain, said 3-D training provides the just-in-time training concept necessary in a condition-based maintenance environment. “You don’t give people knowledge until they need it. The key to all of this is to teach at the teachable moment, which is rarely in a classroom. By using interactive manuals, you can bridge the gap between the classroom and the field,” Batstone said. The training is provided on existing mobile technology and accessible to the maintainer at the point in time that he or she needs it. Ngrain is currently working with branches of the military in Canada and the United States.
Condition-based maintenance is providing us the information we need to be proactive,” said McLemore-Baugh. “From a logistics standpoint … because we know the status of the aircraft, we now have a better idea of how to maintain it and know what parts we need and how much to keep in stock.
“This is a complete paradigm shift. And it will take another generation to get truly institutionalized. This will have a positive effect on reducing demand on the entire logistics system.” ♦