Plane & Pilot
Tuesday, April 5, 2011

Caring For Your Aircraft

Part II: All About Engine Monitors

After landing, many pilots do a magneto check before engine shutdown, and again this is a good time to look at the bar graph for a uniform rise in EGTs. If one cylinder isn't behaving itself, have a mechanic check the plugs before flying the airplane again.

J.P. Instruments' EDM-930 (left) is STC'd and TSO'd to replace standard engine instruments. Flightline Systems offers AuRACLE engine management systems (center) for both single- and twin-engine aircraft. Garmin's G1000 glass flight deck (right) offers a leaning function that displays per-cylinder CHT and EGT info.

An engine monitor can be a lifesaver in flight. Plane & Pilot Publisher Mike McMann found that out in his Bonanza some years back: "I was taking off from Montrose, Calif., and the engine started running rough. Looking at the engine monitor, I saw a problem with the #5 cylinder. Returned to the airport, found a mechanic, told him there was a problem with #5, and he found a loose sparkplug wire."

Beyond the basics of CHT and EGT for each cylinder, many engine monitors offer additional options. I personally am a big fan of fuel flow: For many years my wife (a pediatrician) and I have participated in medical mission trips to Mexico with Liga International ("The Flying Doctors of Mercy"). When an unexpected headwind develops, or word comes over the radio that the airport we planned our first stop at has run out of avgas, knowing exactly how much fuel remains becomes critical information. My personal rule is to divert if it looks like I'm at risk of landing with less than a one-hour reserve—and to do it early, because there aren't a lot of airports available in the Sonoran desert!

If you don't have glass, then adding an engine monitor can be a helpful upgrade. it will help YOU operate THE ENGINE efficiently and safely, avoiding early, expensive cylinder overhauls.
Data logging can be a useful feature for monitoring trends, and in some cases dealing with problems—both Mike and I have identified cylinder problems in airplanes we bought after adding engine monitors to them. A pilot interviewed for this feature told us that he had loaned out a high-performance turbocharged single to a friend, and suspected when he got it back that the borrower had abused it. Downloading data from the engine monitor showed that excessive leaning had been used at high power.

Whether you add an engine monitor or have one already, spend a little time with the POH and any other documentation to make sure you know how to get the most from it. Knowing what goes on in your engine will help you fly efficiently and safely!


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