What Goes Into an Effective Engine Monitoring Program
When you mention the concept of trend monitoring to aircraft owners, you'll likely just get a whole bunch of eye rolling and deflections that trend towards the statement, "I just fly my Cessna on the weekends. Only the big guys need to worry about that fancy stuff." And, although this stereotypical reply is bemusing at first blush, it shows a deep misunderstanding between aircraft owners/operators, engine manufacturers, and the engineers who originally designed them.
Sure, oil analysis was more-or-less unheard of back when many of the engines on aircraft were originally designed, but that doesn't mean that it doesn't have any place in the modern operational environment. This goes for everyone, from the largest operators of large turbine engines, down to the weekend warrior and his 150.
So how can a trend monitoring program be established for those operating smaller equipment on an infrequent basis be established?
Well, the first step is to develop a list of parameters that can be easily measured, and then reported. This includes things like RPM, manifold pressure, oil pressure and temperature, vacuum, oil filter contamination levels, CHTs, and EGTs. Be creative and flexible. Although we at Gemco are firm believers that a multi-probe CHT and EGT sensor system is one of the best pieces of equipment you can install on your aircraft, if you don't have it, don't sweat it. Instead, collect what you can. Don't collect information you know has no bearing on the health of your aircraft, or engine. Those who are enrolled on a Gemco program will have a copy of our Trend Monitoring forms that list a variety of useful parameters that can be easily measured. Use these as initial guidance on what you want to collect data on.
Once you've established what you want to record, the next step is to develop a system that allows you to record things on a consistent basis. Even if you only fly once a week, it's important that you continually collect the information you've decided to collect. Information is worthless if you don't collect it. Use a form similar to those developed by those of us at Gemco, and stick with it. If you find that something isn't working on your form, change it. If the form you use works, you'll be more inclined to use it.
The last step in the process is data analysis. This is where things can get more difficult, but not necessarily. One of the easiest, and most important things you can do is graphically plot your data in a program like Excel. All you are looking for are wild deviations from the normal, or a noticeable trend. You can then ask yourself if what you're seeing is what you expected. If not, you can start to work with a certified mechanic to determine what is causing the abnormal activity. The important part is you don't have to be a statistician to analyze your own information. Instead, all you need to do is be able to know what looks normal, and what isn't normal. If you notice an abnormal, then all you need to do is bring the information to the attention of someone who is more knowledgeable about the innards of your aircraft who can track the real problem down.
Oftentimes, when you collect information, multiple data points can reflect a growing problem, so you can verify a growing divergence from the norm by collating different information. This kind of information is invaluable to mechanics and other maintenance professionals. Instead of just coming into the shop and saying "it makes a weird noise," you can walk in and say that, and present them with hard information and trends that can allow them to quickly hone in on a particular problem. This will save you money, and them frustration.
So, the next time you see the words "trend monitoring," don't just shut them out. Instead, develop your own system. Look at what your aircraft is telling you, and you'll find that you experience fewer unexpected problems, have less downtime, and have a better working relationship with your maintenance professionals.