Hartmut, Your post is almost exactly what I was going to put forth regarding mag checks before flight. It is a most reasonable presentation that makes perfect sense. THis forum is a wonderful presentation of years of experience with aircraft in general and Ercoupes specifically, however, there are instances wherein folks seem to feel they must post information for the purpose of posting their opinion and that initiates confusion. I appreciate your post and believe many others will value a sensible application of common sense. Many thanks, Lee Browning Guys We have to look at the purpose of the run up to come to a usable solution. Two reasons come to my mind: 1. we test for function of all crucial parts. Magnetos and Carburetor heat . 2. we test for take off performance. For the first test we don't need a full throttle run up. We have to notice a drop during the magneto test to verify that both are working and can be switched off. And the carburetor heat is tested also by noticing the drop in rpm. The magneto drop should not be excessive, a drop of more than 100 rpm would indicate a non firing or barely firing spark plug. That's why you do the run-up. Not to satisfy some numbers. Since the Ercoupe brakes are suited for slowing the plane down, but not so much for holding the plane at full throttle in a static position, it is common sense to do this kind of run up at a lower rpm. I am using 1600 rpm and I am seeing magneto rpm drops between 25 and 75 rpm. Anything more and I have to look deeper into the issue. Think about it, you don't do a full throttle run up in a tail dragger either. As for the performance test, I do briefly a full power test where and when applicable before take off to be sure to reach the recommended static rpm. That rpm value differs between the allowable engine propeller combinations. For the latter reason, I am also inclined to say that the experienced drop in rpm when doing the magneto test also depends prop pitch. So in result, there is no strict rpm to do the run up with. Nor is there a rpm number of magneto drop that you should or should not see. Rather than requiring a certain rpm number, I would recommend using always the same number when doing the run up. Learn what the drop usually is and be alert when it is different from the usual. Hartmut
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