My first in-flight mechanical failure

A Lieberman wrote:


snip
My rational for this would be why change a configuration for what appeared
to be a good running engine especially when you were able to cool the
engine temperature with mixture?

A valid point. I had typed this wordy response, but looking back at the
incident, it was much more simple: Given the severe clear, nearby
airports, and high altitude, I believed I had many options in the event
of a complete engine failure and didn't see the risk in testing the
mags.

One only need to recall the Alaska Air accident off the coast of
California to understand that too much troubleshooting can sometimes be
fatal.

I am curious, had it been hard IFR, would you have check the mags???

Hmmmm... I would be *much* more conservative in hard IFR. In fact, I
most likely would have declared an emergency. The key point to
understand in my actual scenario is that I had many options. In hard
IFR, I would not have had but a few.

--
Peter

Ron Rosenfeld wrote:

Although you were not in a DISTRESS situation, as defined by the AIM, you
were clearly in an URGENCY situation. And BOTH are reasons for declaring
an emergency.

Perhaps. In my case, I received exactly what I needed to end the
flight: Direct to the airport and remain high with pilot discretion to
descend when I felt it was safe to do so.

Had ATC deviated from my plan or (as I replied to Alan), had it been
hard IFR, I would have declared an emergency.



--
Peter

Peter R. wrote:

as I replied to Alan)

Sorry, Allen not Alan.

--
Peter

I wrote:

snip
OK, there's the problem, a dead mag.

I just received a call from my trusted mechanic early this morning.
He discovered that a capacitor failed in-flight, which in turn grounded
the mag.

This is a bit beyond my limited knowledge of aircraft mechanics and I
cannot correctly explain what a capacitor does, but the good news is
that it is much cheaper to replace a capacitor than a mag.

--
Peter

I'm with you on that one Peter. I didn't get the impression that you were
hesitant to declare an emergency for any other reason than you didn't really
think it was an emgergency. You received the same results (i.e. service from
ATC) and that's what counts.

Thanks for the post. I hope I'm able to act the same way if I ever encounter
a similar situation.

Regards,

Marco

"Peter R." wrote in message
...
Peter R. wrote:

as I replied to Alan)

Sorry, Allen not Alan.

--
Peter

In article , Peter R.
writes:

Not knowing what to
expect, I was pleasantly surprised to discover that the engine continued
to deliver with no roughness.

Landing was uneventful...

Good show. That's why they give you two of those.

Years ago, had an emergency in a SuperCub when a hydraulic valve lifter
assembly went fubar at 6000 agl. Performance was slowly deteriorating, and
streaks of oil started appearing on the windscreen. We declared an emergency
and arrived over FUL with over 3000 feet to spare. The clowns in the tower
wanted to vector us off towards Disneyland to decend so that they wouldn't have
to mess up the traffic in the pattern. Still not knowing the exact cause of
the problem and being concerned that the engine might quit at any moment, we
didn't think that flying away from a made airport was a good idea, and in no
uncertain terms declined the instruction. The traffic was cleared and after a
few tight circles we landed with no problem. We cleared the runway and shut
down.

Later we found out that the tower guys had a bet going on wether or not we had
run low on fuel. After landing, they had expected to see us sneak over to the
fuel pit. They didn't expect to see us imediately shut down off the taxiway.
When one of the ground workers came over and saw oil dripping out of the
engine, their contest was resolved.

John

Peter R. wrote
I just received a call from my trusted mechanic early this morning.
He discovered that a capacitor failed in-flight, which in turn grounded
the mag.

This is a bit beyond my limited knowledge of aircraft mechanics and I
cannot correctly explain what a capacitor does, but the good news is
that it is much cheaper to replace a capacitor than a mag.

In case you ca

Most mag installations in modern (read - designed for electrical
systems and radios) aircraft have a capacitor between P-lead and
ground. This absorbs some of the electrical noise, and generally
reduces static on the radios.

These capacitors fail with depressing regularity, but they usually
fail 'open' - that is, they stop doing their job and radio noise
increases, but the mag keeps working. This is the first time I've
heard of one failing 'shorted' - but if one does fail shorted, you
ground the P-lead and it's as if you turned the mag off.

Glad that worked out for you - those things ARE cheap - should be
about $30 for the part and 30 minutes to change it.

Michael

Michael wrote:

In case you ca

Of course I care. Hence the secretly placed bait, which you
thankfully took!

Most mag installations in modern (read - designed for electrical
systems and radios) aircraft have a capacitor between P-lead and
ground. This absorbs some of the electrical noise, and generally
reduces static on the radios.

Very interesting. Over the last three months I have been having mag
noise problems (pop-pop-pop on frequency) whenever I used the Garmin
G430 com radio and full power, almost exclusively when tuned to a higher
frequency (130.00 or above). This interference did not occur with the
older B/K comm radio I use as my second radio, so I would end up using
the B/K radio during cruise.

When I asked a trusted avionics shop about this, they explained that the
mag itself was causing the interference and that the Garmin circuitry
was more sensitive to the interference than the older B/K radio. Based
on your explanation, I wonder now if it was really this capacitor
showing signs of imminent failure?

These capacitors fail with depressing regularity, but they usually
fail 'open' - that is, they stop doing their job and radio noise
increases, but the mag keeps working.

Good to know.

This is the first time I've
heard of one failing 'shorted' - but if one does fail shorted, you
ground the P-lead and it's as if you turned the mag off.

That is almost word-for-word how my mechanic explained the mag failure.

Thank you for your explanation.

--
Peter

JohnMcGrew wrote:

Later we found out that the tower guys had a bet going on wether or not we had
run low on fuel.

Nice to see someone casually betting on what could be a life or death
situation. Unlike a coach betting on his own team, though, at least the
controller gave you what you needed to have a successful outcome,
regardless of the side they chose in the bet.

--
Peter

Michael wrote:

These capacitors fail with depressing regularity, but they usually
fail 'open' - that is, they stop doing their job and radio noise
increases, but the mag keeps working.

Which would yield an unexpectedly "hot" prop with the switch in the "off"
position, yes?

- Andrew