MAYDAY in the Everglades

George Patterson wrote:
Marty from Florida wrote:

I didn't touch the mags for concern I'd kill the engine.

I agree with you completely. Switching to one mag would help only in
a situation
in which a mag has jumped time. Your description of the symptoms
doesn't match
what happens when a mag's mistimed (backfiring usually comes into the
picture in
this case). I would not have touched the ignition switch.

I've had instances of mag failure where switching to one improved the
situation quite a bit. One was a bad timing gear that did include the
backfiring, but another was a shorting distributer block that made the
engine extremely rough and caused a power loss. In that case, I
switched to the good mag and had a much less worriesome ride home.

I guess I don't completely understand your (or Marty's) reluctance to
at least check the mags in flight. Even at best glide, the engine is
not going to come to a stop because you grounded a mag. If it gets
worse, you just switch back, then try the other one. At some point,
you decide which combo (left, right, or both) works best and you leave
it there.

Maybe there is something I haven't considered. If so, I would
welcome enlightenment.

John Galban=====N4BQ (PA28-180)

wrote:

I guess I don't completely understand your (or Marty's) reluctance to
at least check the mags in flight.

On a Lycoming, each mag controls half the plugs on the top and half on the
bottom. There are a variety of problems that will lead to fouling of the lower
plugs. If I start switching mags on an iced up engine, there's a good chance it
will die. There's also a pretty good chance that it won't restart when I switch
back to both. Especially on a carburetted engine, you run a big risk of flooding
the engine while it's windmilling. As long as the engine's running, I won't take
a chance on switching mags. It's just something I'm not prepared to do.

George Patterson
There's plenty of room for all of God's creatures. Right next to the
mashed potatoes.

wrote:

snip

I've had instances of mag failure where switching to one improved the
situation quite a bit. One was a bad timing gear that did include the
backfiring, but another was a shorting distributer block that made the
engine extremely rough and caused a power loss. In that case, I
switched to the good mag and had a much less worriesome ride home.

I guess I don't completely understand your (or Marty's) reluctance to
at least check the mags in flight. Even at best glide, the engine is
not going to come to a stop because you grounded a mag. If it gets
worse, you just switch back, then try the other one. At some point,
you decide which combo (left, right, or both) works best and you leave
it there.

Maybe there is something I haven't considered. If so, I would
welcome enlightenment.

John Galban=====N4BQ (PA28-180)


Years ago I was flying a C-150 and it started running real rough. I did
an airborne mag check and found it ran better on one mag. I flew the
remainder of the trip (about 40 minutes) that way and reported this to
the FBO. Can't remember now what the problem was.
--
Regards, Ross
C-172F 180HP