Why Don't You Have an Engine Monitor?
I sometimes find it hard to believe, but lots of owners of large displacement engines don't have multi-probe engine monitors. Given what they cost—that's to say not that much—these instruments ought to standard equipment on two counts: fuel savings and safety.
In an era of $6 avgas, leaning correctly is a survival skill and you can't do that confidently without knowing CHTs and EGTs accurately. And whether you agree with it or not, lean-of-peak operation saves big on gas—probably enough to pay for the monitor in a year if you fly much.
The fine art of interpreting CHT/EGT multi-cylinder digital display indications has sometimes been accused of being akin to reading voodoo bones. That's to say there can be any one of a number of interpretations of just what the display is trying to tell you. There's a hint of truth to that claim, because it's possible for certain untoward indications on the display to have more than one possible cause.
OK, we can agree to disagree on this. But digital multi-cylinder displays have so much to offer that it's hard to see why anyone who can afford one chooses not to. If you figure the potential money saved over the life of an engine, they certainly can be justified financially. Moreover, the peace of mind you get from seeing that old friend reading happy engine thoughts does provide a measure of solace that all is well. If you're on the fence about an engine monitor, we've published a courtesy article from this month's issue of Light Plane Maintenance. Click here to have a look.
In that article, we explain some of the multiple interpretations that occasionally give rise to confusion.
Understanding the CHT and EGT indications is a good start, not only as stand-alone indications, but also how they may work to compliment each other. Consider that you can isolate individual cylinder problems, regardless of the cause, and there have been a number of engine saves from pre-ignition or severe detonation that have been credited to these displays setting off alarms of impending engine melt-down.
But it doesn't have to be dramatic to be meaningful. Long-term, low-magnitude damage can take place and be undetectable by any other means than a multi-cylinder display, but some effort at learning by the pilot is needed to maximize the utility of these devices. Check out the article to learn more.
Also in this issue of LPM, we look at fuel injection nozzles, turbo maintenance and bladder care—not yours, your airplane's fuel bladders. Check out the links in the article for more in LPM.
Kim Santerre is editor of Light Plane Maintenance.