Private flying help--magneto checks

[RansS9]

The crux of the problem....... is L-both R-both good enough or is All-both needed? And if so does it run the risk of damaging the engine? Is that risk dependant on the exact prop engine exhaust installation?

We the "Private Flying Mob" are perpetuating the confuscion. Any chance you could join us and shed some light!

Apologys
1)Probably not the way the forums are suppose to be used (admin please feel free to quash) but didn't know how to attract the attention of people who might actually KNOW the answer.
2)Mundane problem..but if it keeps those of us chugging around in light airplanes (or walking around said airplanes) safer ..what the hell!

[stevef]

Rans, further to my post in the Private Flying forum, this might be of use:

The magneto safety check is conducted with the propeller in the high rpm (low pitch) position at approximately 1000 rpm. Move the ignition switch from 'Both' to 'Right' and return to 'Both'; from 'Both' to 'Left' and return to 'Both'; from 'Both' to 'Off' momentarily and return to 'Both'.
When switching from 'Both' to a single magneto position, a slight but noticeable drop in rpm should occur. This indicates that the opposite magneto has been properly grounded out. Complete cutting out of the engine when switching from 'Both' to 'Off' indicates that both magnetos are grounded properly. Failure to obtain any drop while in the single magneto position, or failure of the engine to cut out while switching to 'Off' indicates that one or both ground connections are not secured.
Source: EA-AC 65-12A Airframe & Powerplant Mechanics Powerplant Handbook.
( Note - this is purely a safety check and not an engine run-up mag drop procedure.)
Steve.

[Capot]

Just come across this thread...

FWIW I suspect that RANS was talking abut the mag drop check carried out to check mag function, at TO or cruise revs, so that you know that the engine will run properly when you want it to, rather than the safety check to ensure that the mags are grounding properly when OFF, so that the engine stops when you want it to.

I've never actually done the safety check, which I thought was an engineering one. It's not that I'm against doing it, it's just that no-one ever told me too, when flying.

Again FWIW I always believed that BOTH - RIGHT, CHECK DROP - BOTH - LEFT, CHECK DROP - BOTH, CHECK NO DROP was the right way to do the function check, similar to the safety check.