Ignition switch, what happen when Left or Right is selected

RST Engineering wrote:
Just running down the list in my head, I am going to take the opposite
position. Most aircraft have BOTH mags with an impulse; a small minority
have only one with an impulse.

Jim

Most aircraft have only one mag with an impulse

Not sure to whom you are responding. I don't see that exact text in my posting,
but I did say something like that.

....but I defer to your greater experience.

Dave

I'm not saying I am right, just that off the top of my head without going
down the list with a pencil and paper, it seems that most (if not all)
Cessnas from the 120 to the 210 have both mags impulsed, most Pipers also,
and that is 90% of the fleet right there.

However, I'm also willing to be corrected by my greasywrench colleagues who
are more into engine work than I.

Jim



"Dave Butler" wrote in message
news:1116429660.228058@sj-nntpcache-5...
RST Engineering wrote:
Just running down the list in my head, I am going to take the opposite
position. Most aircraft have BOTH mags with an impulse; a small minority
have only one with an impulse.

Jim

Most aircraft have only one mag with an impulse

Not sure to whom you are responding. I don't see that exact text in my
posting, but I did say something like that.

...but I defer to your greater experience.

Dave

In article ,
says...


Just running down the list in my head, I am going to take the opposite
position. Most aircraft have BOTH mags with an impulse; a small minority
have only one with an impulse.




Well, I certainly can't contest that, but Lycoming did issue a service
instruction some years ago, indicating that motors with two impulse coupled
magnetos should have the right one replaced with a plain magneto.
Implementation at owner's discretion.

Almost all of the make/models that you mention below have an impulse
mag on the left side only.


On Wed, 18 May 2005 09:00:21 -0700, "RST Engineering"
wrote:

I'm not saying I am right, just that off the top of my head without going
down the list with a pencil and paper, it seems that most (if not all)
Cessnas from the 120 to the 210 have both mags impulsed, most Pipers also,
and that is 90% of the fleet right there.

However, I'm also willing to be corrected by my greasywrench colleagues who
are more into engine work than I.

Jim



"Dave Butler" wrote in message
news:1116429660.228058@sj-nntpcache-5...
RST Engineering wrote:
Just running down the list in my head, I am going to take the opposite
position. Most aircraft have BOTH mags with an impulse; a small minority
have only one with an impulse.

Jim

Most aircraft have only one mag with an impulse

Not sure to whom you are responding. I don't see that exact text in my
posting, but I did say something like that.

...but I defer to your greater experience.

Dave

Perhaps those Lycoming powered that came off the production line after the
service bulletin advising to make that switch, but prior to that date they
were double impulse mags.

Let's take just two examples with which I am intimately familiar, since I
just did a mag rebuild on both of them. The Continental O-470L with Bendix
magnetos has dual impulse mags. (Cessna 182 et al)

The Continental O-300D with Bendix magnetos has dual impulse mags. (Cessna
172 et al)

I suppose we can go down the list of every aircraft that was ever made and
start a table. I'm not going to waste my time doing that.

Jim




"Bill Zaleski" wrote in message
news
Almost all of the make/models that you mention below have an impulse
mag on the left side only.


On Wed, 18 May 2005 09:00:21 -0700, "RST Engineering"
wrote:

I'm not saying I am right, just that off the top of my head without going
down the list with a pencil and paper, it seems that most (if not all)
Cessnas from the 120 to the 210 have both mags impulsed, most Pipers also,
and that is 90% of the fleet right there.

However, I'm also willing to be corrected by my greasywrench colleagues
who
are more into engine work than I.

Jim

"OtisWinslow" wrote in message
m...
That's a good thing to pay attention to. You can also check it at
idle before shut down by briefly turning the switch to "OFF" and
see if the engine starts to shut down.

Emphasis on "at idle", of course.

To drum up business for A&Ps, via A.D. 78-09-07
"Guillermo" wrote in message
...
I was wondering what is exactly the function of the impulse-coupled
magneto.
I've read about them a little bit on the web, but I'd like somebody to
explain it in simple terms.

thanks

guillermo

"Tauno Voipio" wrote in message
...
Greg Farris wrote:

In article ,

says...


Assuming just one magneto with an impulse coupling, the other magneto
is
shorted and the starter is engaged (by electrical relay,
generally...I'm
not
aware of any airplane starter that runs the current straight through
the
mag
switch).

Note also that this is true only of systems that use an impulse
coupling
for
starting.

Of course, you could have just posted that information, rather than
turning
into a pop-quiz.

Pete




What's the logic of grounding the non impulse-coupled mag during
starting?
(Not a "pop quiz" - I'd like to know).

G Faris



The non-impulse magneto will fire earlier, if at all, and it may
back-fire the engine, as the cranking speed is slow.

--

Tauno Voipio
tauno voipio (at) iki fi

"Peter Duniho" wrote in message
...
"OtisWinslow" wrote in message
m...
That's a good thing to pay attention to. You can also check it at
idle before shut down by briefly turning the switch to "OFF" and
see if the engine starts to shut down.

Emphasis on "at idle", of course.


Yes. At idle. And I should have added that if it starts to shudder and
die don't turn it back on. When I do it it's just a brief switch to the
OFF position and back on.

Yes. At idle. And I should have added that if it starts to
shudder and
die don't turn it back on.

It WILL start to shudder and die if you turn it off, unless there's a
bad P-lead connection or mag switch. You want it back on so you can
shut the engine off with mixture, not ignition.
I get really annoyed when students go to "Off" during the runup
and mag testing. We try to get them to hold the key firmly, not by its
edges, so that it won't inadvertently snap over to "Off" when they
select "R." They almost always immediately turn it on again (instead of
letting it spool to a stop and restarting) and the exhaust makes an
almighty BANG and I have to look closely at that muffler and piping
during inspections to find the cracks that often result.
That was the big joke when we were young, right? Turn of the
auto's ignition and back on again to get the big boom from the exhaust
system. Doesn't work anymore with fuel injection. Saves exhaust
systems, no doubt.

Dan

I get annoyder when they go the other way and grind the starter bendix. I'm
not sure which one is more expensive to fix.

{;-)

Jim


I get really annoyed when students go to "Off" during the runup
and mag testing.