Ignition switch settings

"Jon Woellhaf" wrote in message
...
And I've been trying to learn for years why R is on the left and L is on
the right.


My recollection from the last time this was discussed is that the labeles
used to be the other way around so that "L" on the left meant that the left
mag was grounded and, therefore, the right mag was firing. Then, to keep it
more consistent with the "Off" and "Both" labeling, they switched the
labeling but left the right key position which grounded the right mag so
that the left mag was firing now labeled "L"?

Doesn't bother me a bit. If one mag fails an RPM drop, I'm gonna check the
wiring to both any. 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.

Say, why don't they label them "Off", "B", "T", and "Both"?
-------------------------------
Travis
Lake N3094P
PWK

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.


No, but he should know that that the Right mag is hot (firing plugs) and the
Left mag is cold (not firing) when the switch is in the "R" position, and
that the Right mag is cold (not firing) and the Left mag is hot (firing
plugs) when the switch is in the "L" position. That much systems knowledge
would seem usefull for a safe and reasonable Go/NoGo decision prior to
take-off, and also to explain a problem to an efficient manner.

Knowledge of the specifics of how the ignition system works could be very
usefull in the case of "stealing your oun airplane" because you lost the key
at a remote hunting/fishing spot; but I can not imagine that being part of
an accredited licensing test.

Peter

And I've been trying to learn for years why R is on the left and L is on
the
right.

I wonder. Maybe because the ancient systems used two toggle
switches labelled "L" and "R" and they were connected to their
respective mags. When you turned off the L switch, you were running on
the R mag. It was self-evident. Our two Citabrias still have this
setup and I bet American Champion is still building them that way.
When Bendix came up with the combination starter/mag switch, the
internal mag-shorting contacts were set up in the same order but now
they had to label them opposite so that you knew which one you were
sparking on.
I'd rather have the toggles in my Jodel but it makes the
airplane so much easier to steal. If you can get in you can go.

Very true. But I've known pilots who thought that might be very usefull if
they lost their key at a remote fishing hole...

Peter
(It is an amusing thought)

On Sat, 3 Mar 2007 19:11:50 -0600, "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.

On the right (or left) looking toward the propeller, or t'other way
round? (And tractor or pusher? And are the mag designations different
on the two engines in a Cessna 337?) Maybe it's time to label mag
switches Port and Starboard, mateys!

Don

wrote

I'd rather have the toggles in my Jodel but it makes the
airplane so much easier to steal. If you can get in you can go.

You could rig up a cover to put over the toggles, with a place to put a
padlock on the cover, as long as it is not a certified plane.

Would altering a plane in that manner be against the rules for certified
planes? It would be in the certified plane's regular certified condition,
while it was being flown, after all!
--
Jim in NC

"Travis Marlatte" wrote

Say, why don't they label them "Off", "B", "T", and "Both"?

Excellent suggestion! Why not? It might make too much sense, that way!

One could put an "auxiliary label" on panel next to the "L" and "R" with a
Dyno Label, or with another favorite method, though.
--
Jim in NC

"Travis Marlatte" wrote in
t:

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.

"Peter Dohm" wrote in message ...
:
: No, but he should know that that the Right mag is hot (firing plugs) and the
: Left mag is cold (not firing) when the switch is in the "R" position, and
: that the Right mag is cold (not firing) and the Left mag is hot (firing
: plugs) when the switch is in the "L" position. That much systems knowledge
: would seem usefull for a safe and reasonable Go/NoGo decision prior to
: take-off, and also to explain a problem to an efficient manner.
:
: Knowledge of the specifics of how the ignition system works could be very
: usefull in the case of "stealing your oun airplane" because you lost the key
: at a remote hunting/fishing spot; but I can not imagine that being part of
: an accredited licensing test.
:
: Peter
:
:

But they sure as heck should know that turning off the master switch will not turn off their engine.

There are some old engines that did use battery power for
the ignition and in those, the battery master must be on.
But, in general aircraft built in the post WWII period have
two independent magnetos and the battery is used for lights,
starting and radios, etc. Some aircraft had one magneto and
one coil/distributor [like a car], so the AFM/POH should be
read. Also ignition operation should be checked on the
ground as part of the pre or post-flight checklists.



"Blueskies" wrote in message
t...
|
| "Peter Dohm" wrote in message
...
| :
| : No, but he should know that that the Right mag is hot
(firing plugs) and the
| : Left mag is cold (not firing) when the switch is in the
"R" position, and
| : that the Right mag is cold (not firing) and the Left mag
is hot (firing
| : plugs) when the switch is in the "L" position. That
much systems knowledge
| : would seem usefull for a safe and reasonable Go/NoGo
decision prior to
| : take-off, and also to explain a problem to an efficient
manner.
| :
| : Knowledge of the specifics of how the ignition system
works could be very
| : usefull in the case of "stealing your oun airplane"
because you lost the key
| : at a remote hunting/fishing spot; but I can not imagine
that being part of
| : an accredited licensing test.
| :
| : Peter
| :
| :
|
| But they sure as heck should know that turning off the
master switch will not turn off their engine.
|
|

"Jim Macklin" wrote in message ...
: There are some old engines that did use battery power for
: the ignition and in those, the battery master must be on.
: But, in general aircraft built in the post WWII period have
: two independent magnetos and the battery is used for lights,
: starting and radios, etc. Some aircraft had one magneto and
: one coil/distributor [like a car], so the AFM/POH should be
: read. Also ignition operation should be checked on the
: ground as part of the pre or post-flight checklists.
:
:
:

How old are you talking, Jim? Any specifics? Engine, airframe?