Wright 3350

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As of 1945, the vast majority of R-3350 flight hours were in B-29's so it makes sense that you hear of more engine fires on B-29's. I worked with a fellow who had worked on refurbishing B-29's for the Korean War. He mentioned that the B-29 was the last big airplane to use hose clamps on fuel and oil lines and they had a lot of trouble with leaks during acceptance flights on refurbished aircraft. He said that they tested different clamps and found that the radial style hose clamps had less tendency to loosen then the tangential style. I think that people get carried away criticizing the use of magnesium as P & W and many other companies also used magnesium without serious problems. Solid magnesium will not burn; it has to be in a liquid state to ignite. If you have an engine installation that is prone to fires, the magnesium will add fuel to the fire but it's not the reason that you have a fire problem. A former instructor pilot mentioned that they had lots of brake fires.
 
Solid magnesium will burn, I've done it, but yeah it maybe melts a bit to start. There are plenty of stories of aircraft engines burning, that the Co2 systems would not put out because of burning magnesium.
And very likely these Mag fires are what gave the old Piston airliners such a bad reputation. It it so surprising that those engineers in the day even considered it.
Here is some info to check out.


View: https://www.youtube.com/watch?v=cSusDFuaAmsSolid magnesium burning.
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The rain showers in the area increased the intensity of the magnesium fire in the engine. (This is after the first story.)
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An ounce of prevention can save a ton of money down the road!

aesmn.org
Engine fires were exacerbated by igniting engine components manufactured from a magnesium alloy. (Read down into the article a bit.)
 
You'll note that you can see the speciment melting and flowing before he gets it to ignite. In my experience throwing magnesium into a fire, you wait wondering why it isn't burning and then it ignites into a white hot flame after it has enough time to melt. Once you get a speck of liquid to ignite, the heat is going to melt the adjacent metal which will then ignite. I remember my father saying that there were stories of a magnesium case igniting due to heat from a runaway prop and since the fire extinguishers are pointed at the carburetor they were useless.
 
Going off on a tangent, a former B-24 crew member worked on our flightline. He said that he had always been one of those people who said you could never get them to jump out of an airplane. They had an engine fire on a night training flight out of Muroc Army Airfield. He said that he looked at that engine burning on the wing and he was the first to grab his parachute. As Richard Pryor said, fire is a great motivator.
 
Specimen melting? I mentioned that in my above post. Still proves it burns and doesn't just need to be small chips or dust. Just the wrong material to make aircraft engine parts from.
 
PWR4360-59B said:
Specimen melting? I mentioned that in my above post. Still proves it burns and doesn't just need to be small chips or dust. Just the wrong material to make aircraft engine parts from.
Click to expand...
Like the R-3350, the R-4360 used magnesium for crankcase sections other than the power section. Perhaps you would like to change your handle since the R-4360 is made from "the wrong material."
 
BobB said:
Like the R-3350, the R-4360 used magnesium for crankcase sections other than the power section. Perhaps you would like to change your handle since the R-4360 is made from "the wrong material."
Click to expand...
A technicality, the actual crankcase sections were not made from Magnesium, the sections bolted to it are, and the purpose of them is for induction, accessories, and propeller gear reduction, and yes those casings are magnesium. The power section is the crankcase. The other cases can not be classified as crankcase, there is no crankshaft in them. Just like in a car a bellhousing or flywheel housing is not the crankcase or block, which ever nomenclature is preferred.
For as sharp as the engineers were in those days, I can't understand that blunder. (edit here) The blunder is the use of magnesium on the engine.
 
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P&W also built an engine called the Wasp(military R-1340) with the main case/power section/crankcase consisting of an aluminum front half and magnesium rear half. My father worked at a base that put ninety of those engines in the air every day and somehow they managed to refrain from bursting into flames. Likewise, the Cessna UC-78 Bamboo Bomber used two R-755 engines with magnesium main case rear half, nose case, rear case and intermediate bearing plate and in millions of hours of flying the engines were highly reliable, the wood spars on aircraft sitting outside being the biggest problem. OMG! Wood spars! Those could burst into flames!
 
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