New Engine Health Monitoring System Adds Safety, Saves Money

Air Safety Week, August 2, 2004

'Predict the unpredictable,' developers proclaim

A new engine monitoring system is demonstrating its potential to save money and improve safety through increased powerplant reliability and earlier warning of potential problems.

Originally developed for the nuclear power industry, where tracking reactor operation was critical to anticipate and prevent such things as pump failures, the system has been adapted for aviation use. Developed by an Illinois-based company called SmartSignal, its so-called eCM software is touted as a considerable advance over traditional engine monitoring programs. It employs more sensitive monitoring based on the known operation of each engine, as opposed to tracking engine performance relative to a "baseline" of all engines.

While there often can be a big difference between what might be called "brochure-based performance" and actual experience in the field, this system seems to be living up to its proclaimed advantages. After a two-year development trial, it has been fully in use since July 2003 at Delta Air Lines [DAL], the launch customer, monitoring 1,100 of the giant carrier's engines - nearly all of its stock.

SmartSignal's John Kerastas said, "We've helped prevent delays, in-flight shutdowns and diversions." To David Garrison, general manager of propulsion engineering at Delta, the system has been a boon. "It's exceeding our expectations," he said. "We felt that the system would pay for itself within a year, and we're on track."

Garrison said the system has contributed to a threefold improvement in the carrier's in-flight shutdown (IFSD) rate, which is now at its lowest in Delta's history.

The business case, however, was not based on operational reliability, but rather on engine materials (i.e., parts) savings. Garrison estimated those savings for an engine undergoing overhaul at anywhere from $1.5 million to $2.5 million per engine. Given the size of Delta's engine inventory, those savings over the course of a few years amount to hundreds of millions of dollars.

Through more sensitive monitoring of engine performance, potential failures can be predicted more accurately. "A cracked blade is a lot cheaper to repair than a failure that trashes an entire engine," Garrison said. With vibration monitoring, for example, "we can proactively address a problem before a pilot reports, it," Garrison added.

The new engine performance monitoring system also measures additional parameters than more traditional systems, Garrison explained, such as stator vane angle positions.

The heart of the system is the way it tailors monitoring to each engine. "The older technology looked at variations in engine performance from a manufacturer's baseline," Garrison said. "It was more generic; now we see variations that we didn't see before," Kerastas explained, "We shrink-wrap our software to each engine's operating profile. By this personalized approach to each engine, abnormalities are flagged earlier."

The data for each engine is transmitted from the aircraft at take-off, when stabilized cruise flight is established, and at hourly intervals thereafter. The data is transmitted via ACARS (airborne communications addressing and reporting system) to a ground site for processing.

The development from a prototype to an operationally useful technology involved challenges. Garrison recalled, "Since it was new, we had to do a lot of customization." Having paved the way, he believes the system can be implemented more smoothly at other airlines. For example, Southwest Airlines [LUV] recently signed a contract to employ the eCM system.

Now tailored to Delta's needs, Garrison said the benefits are becoming more evident as the system matures in service. "My engineering organization has a much better feel for how the fleet's running, so we can better design our overhauls," he said. Those overhauls, tailored to each engine, he added, represent "a lot of value" - as in cost savings.

An engine "watch list" is one of the system's features. "Because we monitor so many engines with five engineers, we've developed a 'watch list' built on rules developed in collaboration with SmartSignal," Garrison said. "Without desensitizing the system at all, we've brought the list of engines on that watch list down from 300 to about 50 engines."

The system has been successful enough to prompt Delta to explore other applications. Tests now are underway at Delta to apply the eCM monitoring system to auxiliary power units (APUs) and environmental control systems. In other words, the cost savings are being proliferated. >> Kerastas, e-mail jkerastas@smartsignal.com; Garrison, e-mail david.garrison@delta.com <<

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