In article ,
"Travis Marlatte" wrote:

"Peter Dohm" wrote in message
...
Right magneto is "hot" (ungrounded). The "OFF" position grounds both
mags.


I know from personal experience that a lot of pilots continue to have
serious misconceptions about such things, but it still bothers me. This
is
the sort of thing that is part of every run-up, and therefore should have
been part of the aircraft systems knowledge requirement to get the
license--not necessarily the grounding issue, but which magneto actually
fires its set of plugs.



I don't get the connection. Why would the licenced pilot need to know which
mag and which set of plugs is firing on Left or Right key position? Know why
the mag check is important and what to watch for during the mag check, yes.

So you can tell which mag has the problem -- ehether it is plugs,
harness or the magneto itself. Sometimes it is just a fouled plug; other
times it is a dirty cigarette; other times it is a loose harness
connection. Learn it and use it!