Peak Is Peak, Other Temperatures Are Cooler!

In the feature article entitled “Not Flying Blind Anymore!” (Midwest Flyer Magazine, August/September 2014, page 26) which describes one pilot’s experience in using an Insight Avionics G4 Graphic Engine Monitor, there needs to be a correction pertaining to Exhaust Gas Temperatures (EGT).

The article states:

Temperatures depicted when leaning lean of peak are “hot,” or degrees hotter than peak temperature, and the temperatures depicted when leaning rich of peak are “cool,” or degrees cooler than peak temperature. Lean temperatures are depicted in “black and white,” preceded by the letter “L,” and rich temperatures are depicted in “cyan,” preceded by the letter “R.”

Based on reader input, the article should be corrected to state as follows:

Exhaust Gas Temperatures (EGT) depicted when leaning lean of peak is measured in degrees “cooler” than peak EGT, at a leaner or lower fuel flow than the fuel flow was at peak EGT.

Exhaust Gas Temperatures depicted when leaning rich of peak are also “cooler” than peak EGT, though at a richer or higher fuel flow than the fuel flow was at peak EGT.

Lean of peak temperatures are depicted in “black and white,” preceded by the letter “L,” and rich of peak temperatures are depicted in “cyan,” preceded by the letter “R.”

Additionally, in aircraft with a 24-volt electrical system, the buss voltage will be annunciated in cyan (not green as stated in the article), so long as the voltage is 24.2 to 28.7 (inclusive). Below this range, the alternator is not charging the battery, and above that, it is overcharging, and the buss voltage will be annunciated in red. End article amendment here.

NOTE: Once you find where the peak EGT is, do not spend a lot of time in that peak EGT zone, especially at high power. Once you find where the peak temperature is, you want to run either lean of peak for air-cooled fuel injected engines, or rich of peak using fuel for cooling carbureted engines.

CAUTION: You do not want to approach the maximum EGT as defined by the manufacturer for more than a few seconds. General Aviation Modifications, Inc. (GAMI) calls this the “big pull,” and “avoid the Red Box.”

EDITOR’S NOTE: The information provided here or elsewhere in Midwest Flyer Magazine is based on limited observations by one or more pilots, operating one or more aircraft, and should not be relied on as technical advice or recommendations for any other aircraft. Readers are urged to refer to the owner’s manual and DVD that come with each Insight Avionics graphic engine monitor, their aircraft operator’s handbook, and their engine manufacturer’s operation guidelines, and consult directly with Insight Avionics (www.insightavionics.com), General Aviation Modifications, Inc. (www.gami.com), and other technical sources.

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