A little engine trouble

Peter Duniho wrote:

Presumably if the engine truly were on the verge of coming
apart, it'd be shedding at least some metal into the oil, right? Or wrong?

Probably not. While there are a few problems that will shed metal particles into the
oil (a disintegrating bearing, for example), most will not. For example, a valve
that's beginning to stick will not.

George Patterson
None of us is as dumb as all of us.

"Peter Duniho"

I've owned the airplane ten years now, and have never heard anything like
that out of it. That was enough for me, having read plenty of the "I
Learned About Flying From That" stories in which a pilot ignored a
seemingly
minor symptom that quickly turned into something major. So I got a
landing
clearance back at TIW, continuing to climb until I was in a position to
make
a normal power-off landing, and then of course landed. Once the power was
pulled back, I did not notice the sound again.

Can't think of a better choice.

I was flying a short hop across Toronto at about 2000' Asl (1200 ' AGL).
There was a sudden, but only slight, hesitation. It steadily deterioted
until I had just enough power to get about 300FPM climb. I was near a
soccer field and a few miles away from a private airport (DeHaviland
Factory). I asked for, and received a clearance to climb to 7000' in CYYZ
Terminal Airspace which would give me an easy glide into the airport. But I
stayed close to the soccer field JIC. My first guess was fuel. No luck
there. I isolated the problem to one magneto. Timing slipped, I assumed as
all cylinders were showing roughly the same EGT (JPI EDM-800). Feeling
confident that the problem was isolated to one half of the ignition system,
I requested the same altitude to within a copule miles of my destination
airport. The problem doesn't seem to be timing though. Plug and plug
hardware look more likely. But why a few of them all at once is still a
mystery.

le moo

www.aerobatics.ca

Stuck valve or maybe a floating valve?

mike regish

"Kyle Boatright" wrote in message
...

One other thing to consider is a stuck valve. Your description sounds
similar to my understanding of the symptoms of a stuck valve.

KB

Well, as promised, here's my follow-up...

Went down to TIW today, after picking up Ron my mechanic first. Yesterday,
one of his employees went over to check the airplane out, full-power run-up,
inspection, etc. He found no sign of anything wrong.

I did my usual thorough preflight, while Ron double-checked some stuff. We
did find a loose rivet on the fixed trim tab on the elevator, but nothing
that would make a noise you'd be able to hear in the cabin.

With nothing left to do but fly, we taxied out, with the plan that we'd
climb over the airport and then depart to the east (back to my mechanic's
airport) if everything looked good. Well, we got to the runway end, where I
did my run-up, and the right mag was *really* rough.

Ron was pretty sure that we were just looking at a fouled plug(s), so we
pushed the power up to burn the crud off. It took a while, and pretty high
power settings, but we actually managed to clear the plug(s).

Oddly enough, his employee found no plug fouling the yesterday. This was
apparently some new accumulation.

Anyway, once we got a normal runup, with both mags running nice and smooth,
we were ready to go. Took off, did our climb (and discovered that TIW has
one of those pesky Letters of Agreement with Seattle Approach where they
abdicate ownership of their airspace above 1700' AGL), and everything
sounded and felt fine, so we headed back to his airport.

The whole flight went just dandy. Ron's current theory is that there was
some small chunk of carbon floating around in the cylinder, that
intermittently was affecting the plug. He says he's seen that before, and
generally the debris makes its way out of the cylinder through the exhaust
before too long. If it got really stuck, it would explain the rough mag
we'd found on the run-up as well.

Without anything to fix and the airplane apparently running fine, I took it
back home to PAE.

Was Ron right about my problem? I have no idea. I'm a bit skeptical, just
because the problem didn't seem like the sort of thing that was affecting
just one plug on one cylinder, but it's hard to say. I one time lost an
entire mag shortly after takeoff, and the only sign that there was a problem
was that my fuel burn was a little higher for the same power setting. The
engine ran nice and smoothly, and I didn't even find out the mag wasn't
working until I did my run-up for my next flight. But I suppose in that
case, all of the cylinders were being affected identically and that if just
one or two was being affected, that might show up as some roughness.

On my way back to PAE, I was reminded about another effect that I'd
forgotten about. Due to the way the sound waves propagate within the cabin,
there are "hot spots" of noise. If I move my head to a particular spot, a
noise that is otherwise inaudible becomes apparent. I was unable to find
such a spot at which I heard a noise identical to what I heard last
Saturday, but I didn't remember this until I was in cruise flight. If I
remember, I'll try moving my head around during my next takeoff and see if I
can come up with the same noise I heard before. Maybe it WAS just the
result of a particular kind of resonance after all, as Larry suggested.

Anyway, that's all I know for now. I realize this thread belongs as much in
r.a.owning as it does here, but I haven't been following that newsgroup, and
it seems on-topic here too, so here it is. Thanks for those who showed
interest...I hope it wasn't too much of a letdown to not find out exactly
what the problem was after all. I guess a theory is better than nothing.


Pete

On Wed, 16 Jun 2004 18:09:46 -0700, "Peter Duniho"
wrote:

I had a plug that would fire intermittent in the air (tested
fine on the ground with a pressurized tester). Lesson learned:
No ground-based pressure tester can replicate the heat/pressure the
plugs are subjected to at cruise (or high) power settings....

With a 6-cyl Continental, when one plug goes of line, the thing still
runs smooth, it just drops 25 or so rpm and "sounds different".

After putting new plugs in ($300 or so bucks), she runs like an old
Singer sewing machine.

Also, maybe forgive me for saying so, but I'm of the opinion that high
power ground runs in an attempt to clear fouled plugs is (obviously)
way harder on the engine than simply pulling & cleaning them (such is
our fate running 100LL in these older engines these days)..

Bela P. Havasreti

Well, as promised, here's my follow-up...

Went down to TIW today, after picking up Ron my mechanic first. Yesterday,
one of his employees went over to check the airplane out, full-power run-up,
inspection, etc. He found no sign of anything wrong.

I did my usual thorough preflight, while Ron double-checked some stuff. We
did find a loose rivet on the fixed trim tab on the elevator, but nothing
that would make a noise you'd be able to hear in the cabin.

With nothing left to do but fly, we taxied out, with the plan that we'd
climb over the airport and then depart to the east (back to my mechanic's
airport) if everything looked good. Well, we got to the runway end, where I
did my run-up, and the right mag was *really* rough.

Ron was pretty sure that we were just looking at a fouled plug(s), so we
pushed the power up to burn the crud off. It took a while, and pretty high
power settings, but we actually managed to clear the plug(s).

Oddly enough, his employee found no plug fouling the yesterday. This was
apparently some new accumulation.

Anyway, once we got a normal runup, with both mags running nice and smooth,
we were ready to go. Took off, did our climb (and discovered that TIW has
one of those pesky Letters of Agreement with Seattle Approach where they
abdicate ownership of their airspace above 1700' AGL), and everything
sounded and felt fine, so we headed back to his airport.

The whole flight went just dandy. Ron's current theory is that there was
some small chunk of carbon floating around in the cylinder, that
intermittently was affecting the plug. He says he's seen that before, and
generally the debris makes its way out of the cylinder through the exhaust
before too long. If it got really stuck, it would explain the rough mag
we'd found on the run-up as well.

Without anything to fix and the airplane apparently running fine, I took it
back home to PAE.

Was Ron right about my problem? I have no idea. I'm a bit skeptical, just
because the problem didn't seem like the sort of thing that was affecting
just one plug on one cylinder, but it's hard to say. I one time lost an
entire mag shortly after takeoff, and the only sign that there was a problem
was that my fuel burn was a little higher for the same power setting. The
engine ran nice and smoothly, and I didn't even find out the mag wasn't
working until I did my run-up for my next flight. But I suppose in that
case, all of the cylinders were being affected identically and that if just
one or two was being affected, that might show up as some roughness.

On my way back to PAE, I was reminded about another effect that I'd
forgotten about. Due to the way the sound waves propagate within the cabin,
there are "hot spots" of noise. If I move my head to a particular spot, a
noise that is otherwise inaudible becomes apparent. I was unable to find
such a spot at which I heard a noise identical to what I heard last
Saturday, but I didn't remember this until I was in cruise flight. If I
remember, I'll try moving my head around during my next takeoff and see if I
can come up with the same noise I heard before. Maybe it WAS just the
result of a particular kind of resonance after all, as Larry suggested.

Anyway, that's all I know for now. I realize this thread belongs as much in
r.a.owning as it does here, but I haven't been following that newsgroup, and
it seems on-topic here too, so here it is. Thanks for those who showed
interest...I hope it wasn't too much of a letdown to not find out exactly
what the problem was after all. I guess a theory is better than nothing.


Pete

"Peter Duniho" wrote in message
...
Nope, that's not it. It was a little windy that day, but the sound was
far
too regular to be any sort of response to wind gusts.
Anyone have any thoughts on what to do if nothing is found?
As an intermediate step, it occurs to me that even though the oil was just
changed,

Did the plane just have an inspection? Was the fuel filter/gascolator
inspected/cleaned? Whenever my plane just comes out of an annual
I have to run it for a bit to get the air out of the fuel lines. Can also be
bubbles when it's hot but I guess you know that. Usually disappears
by the time I complete the run-up, but if I were quick I guess I could
take it into the air.

Paul

"Peter Duniho" wrote in message
...
Thanks for those who showed
interest...I hope it wasn't too much of a letdown to not find out exactly
what the problem was after all. I guess a theory is better than nothing.


Well, anything which turns out to not be a problem, or is cheap to
fix is worth knowing for the rest of us in case we experience it!

Paul

"Paul Sengupta" wrote in message
...
Did the plane just have an inspection? [...]

Define "just". It did recently come out of its annual inspection. However,
it'd had four flights already since the inspection and before the flight on
which this happened. Also, this is the eleventh annual inspection since I
purchased the airplane, so if air in the fuel lines were a normal
post-annual-inspection thing, I'd think that I'd have seen that before.

I can't rule out fuel contamination, just as I can't rule out many other
things. But the one time I had water (not air) in the fuel, the power loss
I experienced was greater than, and rougher than, what I experienced this
time. So I'm inclined to think it wasn't that.

Pete

"Paul Sengupta" wrote in message
...
Well, anything which turns out to not be a problem, or is cheap to
fix is worth knowing for the rest of us in case we experience it!

I'm just sorry I don't have anything more specific. Granted, that's not
entirely unheard of. Transient problems do sometimes remain simply that:
transient, never to appear again. And of course there's always the "happens
every now and then, but not with enough regularity to diagnose" kinds of
problems.

Even so, I'm always a little more comfortable when I can point to something
and say for sure, "that was the problem". Seems so much more settled that
way.

And frankly, I wouldn't want this particular experience to encourage other
pilots to ignore their "gut reaction" to anomalies. Even after all of this,
with all of the added hassle involved in the follow-up to my aborting the
flight (my rough guess is about 16 man-hours of wasted time, most my own),
I'm happy with my decision, and would do it again if I ever had that feeling
again.

Pete

"Peter Duniho" wrote in message
...
"Paul Sengupta" wrote in message
...
Did the plane just have an inspection? [...]

Define "just". It did recently come out of its annual inspection.
However,
it'd had four flights already since the inspection and before the flight
on
which this happened.

Ah, then I guess not. It's just the first time I start the engine after the
annual that it happens on my plane.

Just an idea.

Paul