Engine burped????

[ruddersup?]

While climbing out the other day in a small 4 cylinder carbureted engine it hesitated (burped). Got my attention but I continued the flight because everything appeared normal and I was in a good position to return safely. This burb only happened once and after landing we took the cowl off and notice an exhaust gasket blown. We checked mags, plugs, valves free to move. Only anomoly was the blown "no blow" exhaust gasket. Could this have been the burp? Replaced the gasket and waiting for weather to fly.

[Colonel Sanders]

If it was a TCM O-200 I would suspect carb ice.

Could also be a sticking valve (applicable to both
O-200 and O-235).

[fleetcanuck]

It could also be a piece of a ring coming through the land (top of the piston) and holding the exhaust valve open momentarily on its way through. That could be checked with a differential test and horoscope. Could also just be a chunk of carbon stuck on the valve seat for a short time.

[AirFrame]

Maybe a chunk of lead stuck in a plug?

[Heliian]

Were you manipulating any engine controls at the time?

Could have been a slug of water in the fuel

Could have been a lot of things.

[Big Pistons Forever]

I second the possibilty of water in the fuel. Have someone push the tail down and re sample the fuel. I once had a C 150 burp in flight. The ramp where it was parked had a slight down slope. When the student drained the fuel the sample showed no water. However when I held the tail down we got more half a sample cup of water out of it .

It turned out the fuel cap gaskets had perished and the tank had taken on water during recent heavy rain.

[ruddersup?]

Engine O-290. Compressions acceptable, plugs good, carb ice (not likely that fast on takeoff and usually a slow loss of power in my experience), valves are free. Original question is can a exhaust gasket produce this reaction when it blows? I've heard of this one time before but asking if anyone here has experienced it?
We flew today and everything normal. Always that doubt in your mind however.

[iflyforpie]

Never heard of a bad exhaust gasket doing anything on normally aspirated engines other than making a mess of the engine... unless it is severe enough to block the exhaust port or burn an HT lead or something.

Since no-blows don't normally blow I'd perhaps look for something that might be complementary to a severe back-fire... like perhaps loose muffler baffles plugging the exhaust. The other suggestions are good too.

What happens sometimes is that an engine burbs and then you have a close look at it and find totally unrelated things wrong with it. The gasket might have nothing to do with it at all.

[SeptRepair]

Worse yet, you cant find anything wrong and the problem never returns, so your left wondering what the hell it ever was.

[Go Juice]

Did you take off with a variable tailwind?

[ruddersup?]

There was no wind at the time and today the a/c flew 2 1/2 hrs with no problem, but............

We're thinking a valve stuck so added some, shhhh, Rislone.

[CpnCrunch]

There was no wind at the time and today the a/c flew 2 1/2 hrs with no problem, but............

The "variable tailwinds on final" is a bit of an inside joke on avcanada. I think it originally started as an excuse for an accident caused by some sort of pilot error, perhaps by pdw, and now it just gets injected into practically every thread just for a laugh.

[ruddersup?]

Thanks Crunch, I've had explanations from "experienced" pilots that scare the hell out of me how they think that a tail wind will affect something like engine cooling (going faster, lol) or rate of climb affected. Scarey to think they are still in the industry never mind flying the big stuff (and they are).

[Colonel Sanders]

The "loss of headwind shear" scenario caused by a
microburst from a Cb was required material, decades
ago on the FAA ATP written. Not sure if it still is, or
if it's still (or ever was) on the Canuck IFR or ATPL.

http://en.wikipedia.org/wiki/Wind_shear ... r_aircraft

Strong outflow from thunderstorms causes rapid changes in the three-dimensional wind velocity just above ground level. Initially, this outflow causes a headwind that increases airspeed, which normally causes a pilot to reduce engine power if they are unaware of the wind shear. As the aircraft passes into the region of the downdraft, the localized headwind diminishes, reducing the aircraft's airspeed and increasing its sink rate. Then, when the aircraft passes through the other side of the downdraft, the headwind becomes a tailwind, reducing lift generated by the wings, and leaving the aircraft in a low-power, low-speed descent. This can lead to an accident if the aircraft is too low to effect a recovery before ground contact.

Between 1964 and 1985, wind shear directly caused or contributed to 26 major civil transport aircraft accidents in the U.S. that led to 620 deaths and 200 injuries.

[CamAero]

That could be checked with a differential test and horoscope.

Not a ouija board or a crystal ball?

[Colonel Sanders]

I love auto-correct!!

But seriously ... I am perhaps not as much of a fan
of borescopes (and other nifty visual trick stuff)
because of the need for operator interpretation.

What one guy sees as Mt Everest, another guy
says, Meh.

[GyvAir]

I always thought it was spelled "horrorscope"..

[fleetcanuck]

Boroscope it is. I am not sure if that was my bad typing or a case of auto correct creeping in. Have some time with an astro compass, not so much with the horoscopes.

I had an oil ring come through the land on my O-200. After the burp we had intermittent excessive mag drops, and a bad result on a differential test. It would also have been visible with the magic scope, as there was about one half inch missing from the top edge of the piston.

[ruddersup?]

Thanks Fleet, we've done the compressions etc. Hopefully a part number didn't go flying out the tail pipe. It's a time temperature thing, as time goes by my temp will go down. I've always flown with the thought that the engine can quit at any moment anyway. Don't have to be paranoid about it but prepared.