Ignition switch settings

Tony Cox wrote:
Here's a question that until yesterday I'd have thought was
obvious.

Cessna-style (and no doubt other) ignition switches have five
settings -- Off/Right/Left/Both/Start. When you're on the "Right"
setting, does it mean you are firing on the right magneto or
does it mean the right magneto is grounded?

Is this covered in the plane's POH?

On Mar 4, 8:55 am, Stubby
wrote:
Tony Cox wrote:
Here's a question that until yesterday I'd have thought was
obvious.

Cessna-style (and no doubt other) ignition switches have five
settings -- Off/Right/Left/Both/Start. When you're on the "Right"
setting, does it mean you are firing on the right magneto or
does it mean the right magneto is grounded?

Is this covered in the plane's POH?

Good question. It isn't. It isn't covered in the
shop manual either.

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!

"Orval Fairbairn" wrote in message
news
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!


You and Peter seem pretty set on this and I don't quite understand why.
Here's two scenarios I'm thinking about:

1) I do a mag check and notice that I don't get an RPM drop on the Left (or
Right) position. So I taxi over to the garage and I say to the guy, I says,
"Say! I think I may have a broken P-lead. Do you have time to fix it while I
go get some lunch?"

2) I do a mag check and notice that the engine runs rough on the Left (or
Right) position. So I taxi over to the garage and I say to the guy, I says,
"Say! I think I may have a fouled plug that I couldn't clear with leaning.
Do you have time to fix it while I go get some lunch?"

Now, if I happened to be out on a lake somewhere and had a fouled plug that
wouldn't clear, I'd walk over to my tackle box, see, and pull out the green,
spotted jitter bug. 'Cause when I'm desperate for dinner, that's what I
always use. In the morning, I'd pull all four of the lower plugs because by
the time I translated left or right for top or bottom on the left or right
side, I'd... well, I'd rather be fishing and, chances are, it's one of the
lower plugs.

-------------------------------
Travis
Lake N3094P
PWK

On Mar 4, 12:53 am, Jackal24 wrote:
"Travis Marlatte" wrote . net:

What is more important to me is that the left
key position has the bottom plugs firing. That's important so that I
can pull the correct plugs the first time to clear an unusually
stubborn fouling.

I thought that one mag controlled the top plugs on one side and the bottom
on the other side.

Yup, on Lycoming. Continental, at least on the smaller engines,
will have the right mag firing the top plugs and the left firing the
bottom. The impulse mag (right) fires the top plugs, since they're
less likely to get wet with oil or fuel.

Dan

wrote

Yup, on Lycoming. Continental, at least on the smaller engines,
will have the right mag firing the top plugs and the left firing the
bottom. The impulse mag (right) fires the top plugs, since they're
less likely to get wet with oil or fuel.

I think you mis-interpreted his comments. He said (at least I think he
said) that one mag fires the top plugs on the left cylinders and the same
mag fires the bottom plugs on the right side cylinders.
--
Jim in NC

On Mar 5, 11:04 am, "Morgans" wrote:
wrote



Yup, on Lycoming. Continental, at least on the smaller engines,
will have the right mag firing the top plugs and the left firing the
bottom. The impulse mag (right) fires the top plugs, since they're
less likely to get wet with oil or fuel.

I think you mis-interpreted his comments. He said (at least I think he
said) that one mag fires the top plugs on the left cylinders and the same
mag fires the bottom plugs on the right side cylinders.
--
Jim in NC

No, that's what I meant. On the Lycoming the left mag fires the
bottom left-side plugs and right top-side plugs. The RH mag fires the
top LH and bottom RH plugs. Continental's smaller engines have the
mags firing all the top or all the bottom plugs, and the larger
engines are arranged like Lycomings.

Dan

On my "larger Continental" the left mag fires top plugs on left side and
bottom plugs on right side. Vice versa for right mag.
DL
wrote in message
ps.com...
On Mar 5, 11:04 am, "Morgans" wrote:
wrote



No, that's what I meant. On the Lycoming the left mag fires the
bottom left-side plugs and right top-side plugs. The RH mag fires the
top LH and bottom RH plugs. Continental's smaller engines have the
mags firing all the top or all the bottom plugs, and the larger
engines are arranged like Lycomings.

Dan

wrote in message
ps.com...

No, that's what I meant. On the Lycoming the left mag fires the
bottom left-side plugs and right top-side plugs. The RH mag fires the
top LH and bottom RH plugs. Continental's smaller engines have the
mags firing all the top or all the bottom plugs, and the larger
engines are arranged like Lycomings.


Haven't followed the whole thread, but on my Lycoming, the left mag fires
all top plugs (TIO540-AH1A).

San

wrote

No, that's what I meant. On the Lycoming the left mag fires the
bottom left-side plugs and right top-side plugs. The RH mag fires the
top LH and bottom RH plugs. Continental's smaller engines have the
mags firing all the top or all the bottom plugs, and the larger
engines are arranged like Lycomings.

How 'bout that. I misinterpreted what _you_ meant.
--
Jim in NC