Davenport Iowa
 

I flew into Muscatine this morning and about halfway thru the trip over Rockford I heard what I thought was a backfire from the front engine. I was preparing to shut down but all vitals appeared to be fine. With plenty of airports in the area and no signs of issues with temp or oil I proceeded onward. When I arrived MUT I landed and was picked up by a company that is building some equipment for my plant in Michigan. As I returned to fly back to Michigan I noticed a puddle of oil under the front engine. Long story short I had a blown cylinder. Crack right in half. I can see the sleeve and the one push rod tube was seperated from the cylinder. I lost about 3/4 of a quart of oil and also broke the opposite rear engine mount. Looks like just the rubber lord mount. WOW! I can't believe I was flying this airplane like that.

Has anyone had any experience with the folks from Carver Areo? They run the FBO in Davenport and have the one here in Muscatine. I talked with one of the mechanics already and he said they have a guy that knows 337's really well. I guess I will see.

How old is the engine? How many hours? I have issues in 3 cylinders on a 305 hour, zero time rebuild. All three had exhaust valve strikes to the pistons. All are on the left side of the engine. The cylinders are finally on their way back from Continental after four+ weeks off the airplane. So far, they haven't given me any reason for this condition. They seem to be avoiding discussing it. They don't answer questions in emails. I get read replies, but no answers.

Glad to hear you landed safely. Hope you have a simple repair.

You might contact Scott Smith, 800-743-1439. He lives and works in Ankeny, Iowa, and may have read on the folk in Davenport. He father in law (now passed away) was an FBO in the area, and Scott worked for him in his early days...

Kevin

Engine has 1800 hours. Last rebuild was in the 80's. It's the center jug on the right side. Annual in May indicated Med to Strong compressions. Uses a about a quart of oil per 10 hrs. Nothing to really indicate problems could occur except it's over TBO.

I thought about Scott and will call him on Monday. There is at least 1 or 2 other 337 drivers in Iowa. I have seen them on the board just can't think who they are.

Good luck to you too Jim, I hope you can get things worked out.

Here is the cylinder

Herb,
Good Picture.
Not as bad as I imagined. This ought to be an easy fix, just replace the cylinder. It looks like the piston is contained, you shouldn't have any spare metal pieces in the pan. Let's hope that is the case.

That's the second 337 blown head I've seen in the last two weeks.

While I was visiting my brother who lives at a private strip in Hawkins, TX recently, the owner of a P337 based there showed me a blown cyllinder he'd replaced. The head had completely broken free of the rest of the cyllinder.

In the TX case, as in the case of Mr. Harney, the pilot was able to continue operating the engine. In fact, he used Unicom to check with a nearby airport to see whether they had a mechanic!

I'd like to hope that if ever my 73 P337 blows a head, the engine will continue to operate pretty normally, with just a little loss in power. But that's hoping for a lot, is it not?

Pardon my ignorance, but I don't get it. How can a blown head not create all kinds of mayhem, including burned wires and hoses, smell of smoke in the cockpit, alarming indications on instruments and worrisome vibrations and noises -- or worse, such as a serious fire fed by a burned-through fuel line?

What am I missing in my understanding of engines, the tons of explosive force a cyllinder contains and the super-hot, 1500 degree gasses that would blast through any crack onto whatever is adjacent?

And what causes a head to blow clean off? In the case of the TX engine, the piston (also removed) had very thick and rough deposits of carbon. I suppose hot carbon deposits could have been causing detonation or pre-ignition, which are said to be a cyllinder's worst enemy.

This is a sincere inquiry. Any expertise out there on this issue?

Best,

GJHumphrey

Once the integrity of the cylinder is compromised, there is no more compression, and no firing of a fuel-air charge, so no cataclysmic fialure like in the movies.

I have quite a bit of experience on radial engines, and metal fatigue is a large factor in head separations. Face it folks, the metal in these engines are starting to get tired. Most of the R-2800's that I'm seeing are running on reduced power settings than what they were originally designed to operate at.

When the TSIO-360 was developed, TCM was using 100/130 octane gas, not 100LL. The anti knock value isn't there with the blue gas.

Thank your for the reply. Your qualificatioins as an A&E and AI lend a great deal of credibility to your views.

Regarding the fire hazard of a blown cyllinder, fuel is still being injected into the head is it not and the plugs are still firing are they not? Wouldn't the atomized gas ignite, even if the cyllinder and compression are compromised?

I'm not trying to be an alarmist, but a fire would be my least favorite kind of emergency and I want to understand the potential.

In the context of your observations about metal fatigue, especially in the day of 100 LL, what kinds of MAP, RPM, EGTs and cyllinder head temps do you personally feel comfortable with in your own airplane?

Thanks.

GJHumphrey
Concord, NH