Checking of the Mag


If you fly a chamber controlled plane, you in actuality were told to play out a “mag check” during the pre-flight runup. Regardless, do you understand how to do it viably, what to look for, and how to interpret the results? Incredibly, many pilots don’t. 

Notwithstanding, most POHs train you to observe the RPM drop when you change from the two mags to just one, and give some most prominent OK drop. This past technique searches terribly for planes that are outfitted with a modernized engine screen (as most are these days), considering the way that EGT rise is a far more prevalent pointer of genuine beginning execution than RPM drop. 

You should focus fundamentally on the engine screen, not the tachometer, when playing out the mag check. What you should be looking for is all EGT bars rising and none falling when you change from the two mags to one mag. 

The EGT rise will usually be 50 to 100 degrees F, yet the particular proportion of rise isn’t essential, and it’s altogether normal for the rising to be fairly exceptional for odd-and even-numbered chambers. You should moreover be looking for smooth engine action and stable EGT regards while dealing with each magneto solely. 

A falling or offbeat EGT bar or unsavory engine sets up a “horrendous mag check” and warrants examining the beginning structure before flying. 

The “mag check” is insufficiently named, considering the way that because by a long shot a large portion of “dreadful mag checks” are achieved by shimmer plug issues, not magneto issues. (It’s really an “start system check.”) 

How might you have the option to tell if the liable party is the connections or the mags? Essential: An inadequate glimmer connection impacts simply a solitary chamber (and one EGT bar on your engine screen), while a wrecked magneto impacts all chambers (and all EGT bars). 

If you get an absurd RPM drop when you change to one mag, yet the EGTs all rise and the engine runs smooth, chances are it’s everything except a horrendous mag yet rather hindered begin timing. 

This is at times achieved by expert mix-up in arranging the mags, but it can moreover be achieved by pointless magneto cam follower wear (possibly as a result of inadequate cam oil) or some other internal mag issue. Blocked beginning planning in like manner results in higher-than-ordinary EGT signs. 

Then again, advanced beginning planning achieves lower-than-standard EGT signs, and besides higher-than-normal CHT signs. Advanced planning is a considerably more certified condition since it can incite blast, pre-start, and veritable engine failure. 

If you notice low EGTs and high CHTs after a plane rises out of help, don’t fly until you’ve had the beginning planning re-checked. 

The standard pre-flight mag check is a tolerably non-mentioning test, and will simply recognize gross disfigurements in the beginning system. To guarantee your engine’s turn over is alive and well, we propose playing out an in-flight mag check at venture power and a lean mix (preferably a lean-of-top mix). 

Since a lean mix is much harder to light than a rich one, an in-flight LOP mag check is the most mentioning and isolating way to deal with test your beginning system. It’s a brilliant idea to perform one each flight or two. 

The in-flight mag check is performed at normal excursion power and average lean mix (in a perfect world LOP). Run the engine on each individual mag for no under 15 or 20 seconds. Assurance that all EGTs rise, that they are consistent, and that the engine moves along true to form on each mag. If you see a falling or unstable EGT, record which chamber and which mag, so your specialist or SAMM account chief will acknowledge which connection is the liable party. 

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