On one Mag? Temptation and decision

Roger Long wrote:

No apparent harm done except to my pride. I did notice that RPM was a
little low on roll out but figured it was just the weather.

We flew into Asheville a few years ago, and the radio died during the approach.
They gave me a green light, but I was faced with handling the departure NORDO the
next day.

I called the tower and got instructions, taxied down, did my runup, got the green,
and took off. She didn't feel right climbing out, but I figured it was just the
mountains. She still didn't feel right in cruise either, though. I was into my
second panel check and considering landing at a nearby airport when I noticed I
was running on one mag. The distraction of dealing with the light gun and traffic
that I couldn't hear was enough to cause me to fail to cut the switch back all
the way to both during the runup.

George Patterson
Great discoveries are not announced with "Eureka!". What's usually said is
"Hummmmm... That's interesting...."

Another option would be to ask around the airport you are stranded at
to see if you can find a ride to or near your home base.

A few years ago I was doing some aerial exploration about 50nm
from home base with my daughter on board. Suddenly something
smelled hot. There was no apparent change in engine or electrical
function, and no smoke - but something was obviously amiss. So I
headed for the nearest airport and landed. An inspection revealed
a hole in the left exhaust collector - and scorched paint on the
cowling (source of the smell). No question but what the plane was
unairworthy. Since repairs would require ordering parts (and it was
a weekend to boot), I secured the plane and headed over to the office
to inquire about possibilities. When I did so a woman standing nearby
said "My husband could have taken you - but he just took off" Bummer.

Then she said "Tell you what - I have plenty of time - I'll drive you
to your home airport". And so it was. About an hour's drive each way -
and she wouldn't accept any payment. There are still good Samaritans
out there!

I later had the plane repaired where it sat, then bummed a ride with
a co-worker (who was passing through that town on a field trip) to
go and retrieve it.

Option 1 - Leave the airplane for repairs and take taxi to home base
to pickup car.

Reasonable assurance of outcome....

Option 2 - Let my wife take taxi to home base and I fly airplane out
on one mag.

Questionable outcome......

QUESTION... What would you have done?

Fix the aircraft before flying it again.

On Sun, 28 Dec 2003 19:14:30 GMT, "Roger Long"
om wrote:

Absolutely, positively, do not fly on one mag if the engine is designed for
two! The second mag is not just for redundancy.

The two spark plugs light off the cylinder charge in two separate places.
Ever heard of burning your candle at both ends? The combustion takes place
faster so the burning is over when the exhaust valve opens and things have
time to cool down a bit. With one mag, the exhaust will be hotter and, in
some cases, combustion still taking place when the exhaust valve opens.
This can burn valves. On some engines, it can even damage the exhaust
piping.


I would think with incomplete combustion it would be cooler in the
cylinder and hotter in the exhaust stacks.

Roger Halstead (K8RI & ARRL life member)
(N833R, S# CD-2 Worlds oldest Debonair?)
www.rogerhalstead.com

Flying even 40 miles this way could be burning the engine's candle at both
ends and maybe even your own.

"Terry" wrote in message
...
QUESTION... What would you have done?

Having been in this position myself, I can tell you what I would have done.
I left the plane at the airport and had it fixed there.

I agree with your decision. Wouldn't you look silly if that remaining
magneto failed on your way home after you'd found one had failed? Would you
feel silly if you'd had a less-than-perfect off-airport landing and died,
just because you didn't want to be bothered with the hassle of leaving the
plane?

You are right, it's tempting to do the wrong thing. That's true in a LOT of
situations, and not just while flying. But there's great satisfaction to be
had in resisting the temptation and doing the RIGHT thing. I'm sure you
know this by now.

Pete

"David Johnson" wrote in message om...
Another option would be to ask around the airport you are stranded at
to see if you can find a ride to or near your home base.

Yep, after our bouts with ignition problems we were heading over the bay one day
and she started misfiring. Sure enough, one mag was completely messed up. We
brought her into the nearest airport, and it only took a few minutes of asking around
until we found some guy in a Maule who was willing to fly us home. Amusingly, after
he agreed to do this it turns out he had been at one of the rec.aviation parties at our
house (he was the flight instructor of one of the crowd and they stopped off at our
place in the middle of his instrument XC).

Roger Halstead wrote in message . ..
On Sun, 28 Dec 2003 19:14:30 GMT, "Roger Long"
om wrote:

Absolutely, positively, do not fly on one mag if the engine is designed for
two! The second mag is not just for redundancy.

The two spark plugs light off the cylinder charge in two separate places.
Ever heard of burning your candle at both ends? The combustion takes place
faster so the burning is over when the exhaust valve opens and things have
time to cool down a bit. With one mag, the exhaust will be hotter and, in
some cases, combustion still taking place when the exhaust valve opens.
This can burn valves. On some engines, it can even damage the exhaust
piping.


I would think with incomplete combustion it would be cooler in the
cylinder and hotter in the exhaust stacks.

And it's not that much hotter in the exhaust stacks either. On a
single mag, I usually see my EGT rise about 50 degrees. Unless you're
leaning hard and making lots of power, I wouldn't worry too much about
running on one mag.

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