Aircraft Maintenance Technology

OCT 2018

The aircraft maintenance professional's source for technological advancements, maintenance alerts, news, articles, events, and careers

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20 OCTOBER 2018 AIRCRAFT MAINTENANCE TECHNOLOGY AIRLINE 22 psi of differential pressure has been allowed in plane fueling. “But, the IATA study found if differential pressure exceeds 15 psi, the possibility of the extrusion of this polymer goes up dramatically,” Leonard says. IATA now requires operators to change the filter media at 15 psi and install an automatic switch that stops fueling when differential pressure becomes too high. Airlines for America (A4A) reports that “A4A and its members have already taken proven steps to reduce the risk of SAP migration from filter monitors, and this includes lowering the fuel monitor differential pressure limit. We are also working together with our partners across the industry to evaluate alternative filtration solutions that do not utilize SAP.” Proposed Solutions Further study by the special interest group revealed that addressing differential pressure was not enough. In fact, they found trace amounts of filter media can be released at any differential pressure. For this reason, the special interest group decided to outlaw the use of SAP by December 2020; putting the date out into the future to give the industry time to develop alternatives. Whether those options make it through an industry-mandated three-part certification process in time to meet the mandate, all equipment is retrofitted in time, and the industry can bear the financial costs of this change, are questions that remain. Marcus Wildschütz, president of FAUDI Aviation GmbH, states he feels some unease as the industry marches toward the 2020 deadline. “I’m surprised the whole industry is not in turmoil right now,” he says. “People are taking a wait-and-see approach, and my biggest fear for the entire industry is they will rush into a decision without any in-depth knowledge.” “Today filter companies are scrambling to come up with alternatives to fueling an aircraft that do not involve full flow monitors,” Leonard adds. “There are three options on the table right now.” The proposed options are: Filter/Water separators (also known as filter coalescers). Taking everything back to filter/water separators, which were effectively used before SAP filters became the norm. Leonard says the positive is that this is “absolute proven technology. There’s no doubt that it works.” A water separator, however, is larger and heavier than its SAP counterparts, and complicating the change is existing equipment. “Existing fueling equipment is built to handle a full-flow monitor. Is it physically possible to swap in a water separator? In most instances, it is not,” Leonard says. Though manufacturers are trying to make these units smaller and lighter in weight, Muzik states, “We can make them smaller and we can make them more compact, it will likely never get to the point where they’re the same size as a filter monitor. The reason monitors were created is because they were small, lightweight, and compact.” Water barrier approach. Currently in development with Parker Velcon, this system takes a 2-inch by 30-inch element and puts a wrap around the outside that repels water. “We’re taking a hydrophobic material that rejects dirt and water,” says Muzik. “It’s a very porous material that is small enough to block the water that’s in fuel, while letting the fuel through.” Leonard maintains he’s seen qualification numbers and believes the system has potential. The water the system collects will drop to the bottom of the housing, where an operator will need to drain the water off through a hole in the bottom of the housing each day. This is what is done currently with filter water separators. “However,” Leonard says, “a filter water separator has a sump to collect water and a sensor to alert the operator. The typical monitor vessel does not have a sump or a sensor. As a result, there’s the possibility of collecting water in a vessel that’s not designed to do it. Operator vigilance will be a necessity.” A Dirt Defense filter with a water sensor. FAUDI’s Dirt Defense filter (a micronic filter) plugs in where the existing 2-inch monitors go, and it stops dirt from going downstream into the aircraft. The Dirt Defense requires a water sensor upstream of the filter vessel. Both FAUDI and Facet have successfully passed EI’s Dirt Defense testing protocol (1599). “The Dirt Defense is available as a drop-in solution. We have raw materials in stock for 10,000 elements. It is easy to manufacture and deliver,” Wildschütz states. “This solution is ready.” This solution will work, states Muzik because “most plane fueling applications have very low water. I say most because if you do have water, then what do you do? Shut down the entire fueling system, and then what? You need to bring in another piece of equipment. You must bring a filter water separator over; this is a solution that has some hair involved in it. It also could have a very high dollar cost. There are some hydrant systems that are notoriously wet. In a very dry system, it will be a viable solution but unfortunately that’s not always the case.” Putting Solutions to the Test A4A reports that “Aviation fuel manufacturers are proposing a number of alternative filtration or sensor technologies that may replace filter monitors. In keeping focus on safety, our members are thoroughly evaluating any proposed solutions before they can be implemented.” This fact prompts Leonard to state that “though Dec. 31, 2020, seems a long way off, it’s not.” There is a global industry effort involving A4A, IATA, the Joint Inspection Group, filter manufacturers, and the EI to fully vet new sensor technologies. “The goal of this work is to identify safe and effective solutions that provide the same or better protection from dirt and water,” A4A officials say. Solutions must first pass EI testing protocols before they can be used. First, the system needs to go through a real test on a real rig, then it must go through what’s called a robustness protocol, which puts

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