When engines make metal

[Exhaustgases]

I see that term occasionally, here and other aviation sites too.
Oh and thanks to the guy that posted the link for ICE pilots here on this site, finally get to watch the show. And it taught me new things about the term making metal. Like when they had a cylinder problem on thier DC3, had all kinds of nice aluminum in the screen. No problem just change the offending parts and button it up and go. Wow, just didn't think that would be done in the aircraft world. I'd think the massive amounts of metal would warrant an engine change, like quick. Anyone have experience with this sort of thing?

[stuntflyr]

Re: When engines make metal

It depends on what kind of metal and how much.
Steel sometimes is a ring, and if a cylinder is down on compression and removed and piston found to have some broken rings, and all of the pieces are found, then the flakes that got to the screens are all that the operator needs to address after the cylinder change. A screen check every flight for a few flights after will show that either the screens content will show less metal each time and normal operation can continue, or the screens will show that the metal content is not decreasing and there is either more or continuing damage within the engine.
Steel is other times roller or needle bearings, bad news.
With "light" metal, like aluminum, it could be a piston scuffing from detonation, cylinder change, with it's piston, might save it again.
Bronze or babbit, or another shell bearing material could be wearing-in evidence if the engine is new, or it could be a wearing out if the engine is older.
It's a bad thing no matter what type metal it is, but sometimes it can be something that can be rectified without removing and replacing the entire engine. When part numbers are readable on these particles in the screen, or they say Snap-On, it's a done deal for replacement!
Chris...

[Smee Again]

Re: When engines make metal

I see that term occasionally, here and other aviation sites too.
Oh and thanks to the guy that posted the link for ICE pilots here on this site, finally get to watch the show. And it taught me new things about the term making metal. Like when they had a cylinder problem on thier DC3, had all kinds of nice aluminum in the screen. No problem just change the offending parts and button it up and go. Wow, just didn't think that would be done in the aircraft world. I'd think the massive amounts of metal would warrant an engine change, like quick. Anyone have experience with this sort of thing?

Speaking for the inline (Merlin) contingent, as has been said, it really depends on the type of material and the overall amount. Small amounts of bearing slough and piston dust is quite common as the engine breaks in; the key is monitoring the amount of stuff as the engine accumulates more hours. It should continue to lessen the more it runs, but if not, it could indicate an issue (it also depends how hard it's run). A great deal of any material (piston coming apart due to detonation, spun bearing, etc.) would certainly require an engine change for an inline motor, along with a thorough flushing of all fluid pathways. Even then you will still find "remnants" of the previous damage in later screen checks, but it should continue to clean up as more run time is accumulated. Hope this helps.

SA

[tjyak50]

Re: When engines make metal

When you find this in the sump screen, you have (had) a problem.



This plane flew for several hours with "Low Manifold Pressure" thinking it would "clear out". Blower drive gear attach faasteners...

[Exhaustgases]

Re: When engines make metal

I know what ya all mean about the type of metal found. But still if that aluminum made it to the screen that means it passed through some things it can damage, like the scavenge pump's, and the pressure pump.
Also if it made it to the screen which to me is the main oil pump screen at the rear sump of a radial engine, then it went through the rest of the system also. Correct? And what about scavenge pump pickup screens, how accessable are they to clean? And yes aluminum is used as bearing material in some engines, so that can be said. But things like pumps and even roller bearings etc can be locked and damaged by even the smallest of particles. I have seen journals slightly grooved from small al particles.
But in the end here thats why I asked, you guys know more about it than I. I thank you for the answers.

[tjyak50]

Re: When engines make metal

IN the case of the picture I presented which is on a small displacement radial engine the big parts were found in the front main sump.

From there smaller pieces were ingested by the scavange pump, ground up and sent to the filter where a bunch of stuff collected. From there to the cooler and the tank where more stuff may have settled.

From there out of the tank to another coarse screen and another medium screen prior to the pump and into the bearings.

Hard to say if pieces big enough to groove bearings made it to the bearings. But it ain't good either way.

[MRE]

Re: When engines make metal

In the case of the Merlin's, not only is there the sump screens and the cuneo {sp} filter which are standard,there is another multi. screen filter.These are checked and cleaned every time the airplane flys. What comes out is looked at very closely.

[Exhaustgases]

Re: When engines make metal

And then there is the cuno bypass valve, that pops open when the filter is plugged or oil is too thick on a cold day start. Then what ever is in the oil will go directly to the gallerys, then to all bearings etc.

[Smee Again]

Re: When engines make metal

And then there is the cuno bypass valve, that pops open when the filter is plugged or oil is too thick on a cold day start. Then what ever is in the oil will go directly to the gallerys, then to all bearings etc.

Like I said, it's really a matter of type of material and amount. Like MRE said, on the Merlin, we used three filter types. The two sump screens (very course), a "last chance" filter (medium course stacked discs), and the cuno (very fine stacked discs). When you begin finding large chunks (sumps screens) and/or a large accumulation of "snow" in the filters (cuno and last chance), it's time to shut it down and/or swap the motor. But like I said, small amounts of "sparklies" are common and should continue to improve the longer the motor runs. The lead plating on the bearings is also an important part of the whole system, as it will absorb small particles that might otherwise score the plating material. So really, it's all a matter of degree.

SA

[Exhaustgases]

Re: When engines make metal

Smee, I know small amounts are nothing, and it is normal. But this one show on ice pilots showed a bunch in the cuno from the cylinder and piston problem. It would have filled a coffee cup or more, so I'm sure the cuno was overwhelmed. It was Al, and still it is stuff that will increase wear and lock needle bearings and way stress gear type pumps, when it gets between the gears.

[Smee Again]

Re: When engines make metal

Smee, I know small amounts are nothing, and it is normal. But this one show on ice pilots showed a bunch in the cuno from the cylinder and piston problem. It would have filled a coffee cup or more, so I'm sure the cuno was overwhelmed. It was Al, and still it is stuff that will increase wear and lock needle bearings and way stress gear type pumps, when it gets between the gears.

Oh yeah, that's ridiculous. I'm talking about an accumulation of stuff from all filters (per run/race) that wouldn't fill a teaspoon, let alone a coffee mug. That sounds like a complete overhaul/replacement situation, not to mention a thorough flushing of all the fluid lines and passages.

SA

[440_Magnum]

Re: When engines make metal

Smee, I know small amounts are nothing, and it is normal. But this one show on ice pilots showed a bunch in the cuno from the cylinder and piston problem. It would have filled a coffee cup or more, so I'm sure the cuno was overwhelmed. It was Al, and still it is stuff that will increase wear and lock needle bearings and way stress gear type pumps, when it gets between the gears.

Well, the application of the engine makes some difference into how much "stuff" you'll tolerate in the screens, too, I would think.

Back one of the years that Dreadnought had an engine issue at the races (after many years of running like a... well.. a Buick), Brian Sanders was asked about the metal that actually showed in the screens since it was a very small amount. He said something to the effect of, 'If that engine was still mounted on an Air Force Globemaster, they wouldn't hesitate to launch from San Diego to Hawaii with it just the way it is. But then they'd have 3 more engines and they aren't running it for sport...'

I've never watched "Ice Pilots," but if its a multi-engine aircraft with engines a little less rare than Merlins, 3350s, and 4360s and there's a paying job to be done, I imagine they'd be willing to run the risk of more engine damage to either a) get the aircraft to a better place to fix it, b) get another payload delivered and get paid, or (best yet) c) both.