Ignition switch, what happen when Left or Right is selected

"Wade" wrote

I've been taught this shtudown procedure, too.
But, what is the magic about turning them BOTH off, simultaneously?

As someone else said, it catches a faulty "off" position, in the switch.
--
Jim in NC

Wade wrote:

If, at idle, you turned off the left mag, and noted an rpm drop,
then turned off the right one, and also noted an rpm drop,
then doesn't that confirm the same thing as turning
both of and feeling for the engine to start to shut-down?

No. Turning off the left mag verifies that that position of the switch will
ground out the left mag. Turning off the right verifies that the switch will
ground out the right mag in that position. You can only verify that "off" really
grounds out both mags by turning the switch off.

George Patterson
"Naked" means you ain't got no clothes on; "nekkid" means you ain't got
no clothes on - and are up to somethin'.

and now the other part of that question... for most key switches that have
"Off" "Left" "Right" "Both" "Start" positions.. what happens when you go to
the "Start" position.?.

BT

"Bill Zaleski" wrote in message
...
You are shorting the magneto that is not selected, therefore
inhibiting it's operation.


On Tue, 17 May 2005 22:49:09 -0400, Martin B
wrote:

Hello,

Here is my question:

On regular aircrafts, like C150, C172, PA28, when we perform the
magneto check where we select Left, than Right, while looking for RPM
drop... what is the switch doing?

When we select Left or Right, do we short that particular magneto or
are we shorting the other one?

I checked all my books and cannot find the answer.

Thanks in advance,

Martin

"BTIZ" wrote in message
news:uhzie.7310$Db6.649@okepread05...
and now the other part of that question... for most key switches that have
"Off" "Left" "Right" "Both" "Start" positions.. what happens when you go
to the "Start" position.?.

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

most correct answer...

"Peter Duniho" wrote in message
...
"BTIZ" wrote in message
news:uhzie.7310$Db6.649@okepread05...
and now the other part of that question... for most key switches that
have "Off" "Left" "Right" "Both" "Start" positions.. what happens when
you go to the "Start" position.?.

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



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

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

what is a non-impulse coupled magneto? (also a question, not a quiz)

"Greg Farris" wrote in message
...

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

G Faris



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

"BTIZ" wrote in message
news:uhzie.7310$Db6.649@okepread05...
and now the other part of that question... for most key switches that have
"Off" "Left" "Right" "Both" "Start" positions.. what happens when you go
to
the "Start" position.?.

BT

Usually, the propeller starts turning and after a seond or two the noise
level increases. Sorry, couldn't pass that one up.

a good answer... but missing essential elements.. LOL

See Pete's answer
BT

"Dave Stadt" wrote in message
m...

"BTIZ" wrote in message
news:uhzie.7310$Db6.649@okepread05...
and now the other part of that question... for most key switches that
have
"Off" "Left" "Right" "Both" "Start" positions.. what happens when you go
to
the "Start" position.?.

BT

Usually, the propeller starts turning and after a seond or two the noise
level increases. Sorry, couldn't pass that one up.