Ultra high-tech monitoring

Ultra High-Tech Monitoring

Software that learns

By Greg Napert

March 1998

One of the biggest problems the maintenance community has been faced with related to turbine engine trend monitoring has been having to interpret the data they collect. Coming up with something meaningful from the sometimes overwhelming amounts of data can be quite challenging.

A company, called Sensa Technologies, recently set out to try to solve this problem by developing software called JENA that would do some of the analysis legwork for maintenance personnel.

According to John Howell, president of Sensa Technologies, most of today's engine monitoring systems monitor a multitude of parameters that must be monitored by an individual. That individual is not only expected to find parameters that are out of limits, but is expected to interpret the data and determine what is wrong with the engine. Howell says that with so many parameters to monitor, that's just not possible.

It is possible, however, to develop profiles for good and bad engines and have computers monitor whether the engines in the fleet match any of those profiles. It then alerts maintenance personnel when an engine needs attention.

Howell explains, "To understand how this concept might work, you first have to understand how current systems work."

The current situation
The typical airline already collects operating data every day. Maintenance personnel at the airlines receive a long list of information that they have to compare against trending baseline data. They then observe the data and identify engines that are tracking out of limits and select them for removal. They have no idea what the problems might be with these engines — only that they aren't tracking properly.

"JENA," says Howell, "takes the information that the airline already collects and takes it one step further. It gives them probabilities on what the engine problems actually are and lets maintenance personnel make the decision if they want to do something about it.

"Another difference with our system is that when it finds a bad engine, it generates an exception report on that engine. The maintenance people are only getting reports on engines that are not meeting the parameters. With their current system, they are getting reports every day on every single engine and it's up to them to determine the bad engines. Some airlines are getting reports for thousands of engines. I've found that many facilities don't even bother using the report. Essentially, their current system is worthless. There is too much information and nothing to interpret it for the operators," Howell explains.

The philosophy JENA subscribes to is that any problem in the engine will actually change a number of parameters, and these parameters will take on certain characteristics based on what the problem is. Howell says, "If you look at each of the parameters individually, they are oftentimes not significant enough to tell you anything. But if you look at them all together, they form a pattern that can tell you what the problem is. In order to tell what these patterns mean, we rely on input from the operator and from past engine data that we have obtained from actual engine inspections and test cell runs. Data obtained at a particular time when an engine was taken out of service is saved as a pattern for the particular problem that was found."

In practice, the customer continuously collects data on engine problems, download operating information, and updates and improves the database.

Another major difference between existing technology and JENA is that it allows the user to improve it's data by incorporating actual findings into the database.

Howell explains, "A typical commercial airline might be pulling and tearing down around five engines per day. When they tear it apart, they look inside and verify what the problem is. This information is plugged into the system which further enhances the data."