two Airbus Super Pumas in which the HUMS apparently didn’t clearly identify component breakdown. At the same time, he notes, early HUMS were famous for false positives. “As a result of these issues and the fact that


some systems weighed in excess of 120 lb. and could cost several hundred thousand dollars, adoption was limited to large helicopters in military and offshore energy segments,” Swayze says. He points to a 2013 RotorHub article titled “Bad Vibrations” in which an engineer is quoted as saying, “It would be fair to say that HUMS has not lived up to early expectations.” After roughly 25 years since HUMS was


introduced, GPMS estimates that approximately 85% of commercial helicopters in service still aren’t HUMS equipped.


HUMS Technology Matures By the 2000s, the technology that HUMS depended on began to change, coupled with the proliferation of smart connected devices and shifting customer expectations. “Te technology is now available to enable


Improved


technology brings HUMS to light, medium markets.


quick and reliable remote download,” says Mayhew. “Tis also offers opportunities to incorporate the collection and harvesting of FDM with HUMS information.” “We saw an opportunity to modernize


HUMS, address its earlier shortcomings, and make the technology accessible to all operators,” says Eric Bechhoefer, PhD, founder of and chief engineer at GPMS. “Te initial HUMS systems were designed for heavy aircraft and for oper- ators that had staff dedicated to data interpre- tation. But today’s systems are lightweight and designed so that the average maintainer can use them to solve everyday problems.” Bechhoefer and his team put their HUMS


you had to get the data off manually. Te cloud wasn’t around, so the aircraft data could only be accessed from a local PC. And the user interfaces were terrible, so you needed experts in signal processing for interpretation.” First-generation HUMS were also questioned,


fairly or unfairly, after some high-profile acci- dents, according to Andrew Swayze, head of strategy and marketing for GPMS, a HUMS developer and manufacturer in Cornwall, Vermont. Specifically, Swayze cites two acci- dents—one in 2009 and one in 2016—involving


system, Foresight MX, through extensive hardware and software development. To address false positives and improve detection, sensor processing and threshold settings were greatly modified. “Our health algorithm typically improves the signal-to-noise ratio by 3 to 4.5 dB. Its fault-finding capability is about 5 to 10 times more sensitive than in other systems,” he notes. “In practice, this means we can identify individual components showing wear, see faults at an earlier stage, track their propagation, and then layer in estimates of remaining useful life


to simplify logistics planning and reduce unplanned aircraft downtime.” Foresight MX was certified on the Bell 407GXi in 2019, under an amendment to the prior 407GX certification. Tis August, it is slated to be certified on another light utility helicopter, the Airbus AS350 AStar. Bell confirms that it’s moving HUMS tech-


nology into its lighter aircraft. “Bell is the only OEM to offer a HUMS for a light single-engine helicopter,” says Brian Tucker, manager for Connected Fleets at Bell. “Currently, we’re working to make HUMS a part of the type design for the larger Bell 525 when that aircraft is certified.” Asked about the advantages that the new-


generation HUMS will offer, Tucker cites the automated alerts to help users know immedi- ately—whether in flight or upon landing—if something needs attention. “Foresight’s pre- diction of remaining useful component life is truly unique and helps operators plan for maintenance,” he says. Tucker also notes Foresight’s bused smart-


sensor architecture. Tis, he explains, puts the data acquisition and processing into the sensor itself, so all data can be acquired simultaneously. “While older systems might acquire data once per hour, the HUMS on the Bell 407GXi acquires data 20 times per hour. In addition, the wiring is simplified,” he says. “Te data bus wires string among the sensors like Christmas tree lights, unlike analog systems with dedicated wiring for each sensor. Tis results in lower weight— just 8.8 lb.”


Using HUMS to Solve Problems Prior to using Foresight, Jeff Byrne, a helicopter pilot and aircraft maintenance engineer for Municipal Enterprises Ltd. in Halifax, Nova Scotia, had no experience with HUMS, but he’s now a fan. “Te Foresight system is too easy,” he says.


“When you land, it uploads the aircraft data automatically, and within two seconds the new information is there on your tablet screen. You look at the component dashboard and if you see all greens, you know you are good to go.” Te system’s troubleshooting and diagnostics features, says Byrne, take the guesswork out of formerly complex diagnostic procedures,


2020 Q3 ROTOR 35


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