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USS Milwaukee broken

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http://www.stripes.com/news/navy/navy-s-newest-ship-uss-milwaukee-breaks-down-at-sea-1.383637

Ruh roo
 

Pat in Halifax

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I just hope it wasn't bad fuel/oil/parts....she got during her recent port visit here....?
 

tomahawk6

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I hope tthey dont have to replace the engine,

http://www.stripes.com/news/navy/navy-s-newest-ship-uss-milwaukee-breaks-down-at-sea-1.383637

Initial indications are that fine metal debris that collected in the lube oil filter caused the system to shut down, but the cause is not known, the Times reported.
 

Occam

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tomahawk6 said:
I hope tthey dont have to replace the engine,

Perhaps some stoker types can confirm, but my understanding is that if they had to stop in the water due to metal debris in the lube oil pumps, then the problem isn't the engines.  She has two gas turbines, and two diesels - any one of which should be able to independently drive the ship.  Would I be correct in assuming the problem would be in the main gearbox or CRPP systems if they had shut down all propulsion?
 

Good2Golf

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Occam said:
Perhaps some stoker types can confirm, but my understanding is that if they had to stop in the water due to metal debris in the lube oil pumps, then the problem isn't the engines.  She has two gas turbines, and two diesels - any one of which should be able to independently drive the ship.  Would I be correct in assuming the problem would be in the main gearbox or CRPP systems if they had shut down all propulsion?

Sounded like an MGB issue to me as well.  Any engine should able to be caged if its lube system becomes contaminated, but at some point, there will be common lube, like on a multi-engine helicopter, were a chip detector activation causes a very rapid descent to the ground and immediate shutdown...perhaps this was the maritime equivalent of that?
 

Stoker

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From an engineering standpoint I would be very concerned if I started to find metal fillings in the LO on a commissioning trip. From what I have heard this occurred immediately after leaving Halifax where the machinery control system triggered an alarm on the port shaft. They cleaned out the filters and locked the shaft line. They continued on and during steering trials early in the morning lost pressure on the stbd combining gearbox and found more filings. The decision was made to immediately get to port. If it was me and I couldn't find the immediate source, I would immediately recommend getting alongside to get this investigated and repaired by the contractor as its most likely still under warranty. Anything with a LO system or gearbox is serious. This is probably something to do with something common to both shaft lines, most likely something feeding the gearbox.
 

tomahawk6

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Good to know that filings doesnt mean a bad engine.I wonder if this will cause the maintainers to look at this issue across the fleet to see if this was an isolated instance or not ?
 

Stoker

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tomahawk6 said:
Good to know that filings doesnt mean a bad engine.I wonder if this will cause the maintainers to look at this issue across the fleet to see if this was an isolated instance or not ?

I would imagine a fleet wide check of all ships has already been sent to make sure this is not a class wide problem. From what I can gather wasn't a problem experienced before on the class.
 

Oldgateboatdriver

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The Freedom class ships don't have variable pitch propellers nor "shafts", in fact they don't have screws but four water-jets for propulsion, each engine driving one water jet, so there is no "main" gearbox either but four separate ones that gear each engine to the impellers of its own water-jet.

I agree with Chief Stoker, though: Any metal filings in the LO system on a commissioning ship is cause for concern (alarm?).

As to why she got completely disabled when she has four separate engines and waters-jets (thus four separate gearboxes), it also depends on the design of the LO cooling system and the concept of operation in use. While she has four engines (and from here on I am speculating, so don't quote me on this), she may have only two LO cooling heat exchangers and the system is set up so either can be used singly to cool everything, switched from one to the other for redundancy or "isolated" and then half the systems run on one and the other half runs on the other. This is all fine if your concern is cooling the oil only. If you lose cooling, likely as a failure of the water pumps or blockage of the water intake, you switch to the other one and it usually resolves the problem.

The problem with such set up is that, if you run everything on one and you get lube oil contamination instead, then you quickly spread the contamination to the whole system being lubricated. Now, on a brand new ship, I would definitely not expect such contamination to occur: The ship has been run at full speed trials and passed, after which the lube oil was (or at least should have been) tested of any problems, and before even running the engines the first time, the whole lube oil system had (or again should have been) flushed and tested. So running everything on one cooler (heat exchanger) was a very very low risk matter. 10 to 15 years from now, perhaps, it would be wise to run on two separate coolers for half the systems each, as I suspect you would do in action also.
 

Stoker

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Oldgateboatdriver said:
The Freedom class ships don't have variable pitch propellers nor "shafts", in fact they don't have screws but four water-jets for propulsion, each engine driving one water jet, so there is no "main" gearbox either but four separate ones that gear each engine to the impellers of its own water-jet.

I agree with Chief Stoker, though: Any metal filings in the LO system on a commissioning ship is cause for concern (alarm?).

As to why she got completely disabled when she has four separate engines and waters-jets (thus four separate gearboxes), it also depends on the design of the LO cooling system and the concept of operation in use. While she has four engines (and from here on I am speculating, so don't quote me on this), she may have only two LO cooling heat exchangers and the system is set up so either can be used singly to cool everything, switched from one to the other for redundancy or "isolated" and then half the systems run on one and the other half runs on the other. This is all fine if your concern is cooling the oil only. If you lose cooling, likely as a failure of the water pumps or blockage of the water intake, you switch to the other one and it usually resolves the problem.

The problem with such set up is that, if you run everything on one and you get lube oil contamination instead, then you quickly spread the contamination to the whole system being lubricated. Now, on a brand new ship, I would definitely not expect such contamination to occur: The ship has been run at full speed trials and passed, after which the lube oil was (or at least should have been) tested of any problems, and before even running the engines the first time, the whole lube oil system had (or again should have been) flushed and tested. So running everything on one cooler (heat exchanger) was a very very low risk matter. 10 to 15 years from now, perhaps, it would be wise to run on two separate coolers for half the systems each, as I suspect you would do in action also.

The ship has two cruise diesels and two gas turbines in a CODAG arrangement. Most likely the port and stbd main combining gearbox that input into two separate gearboxes, that in turn feed the four water jets.  There are two shaft lines involved with this and not separate gearboxes for each individual water jet. It appears that the port combining gearbox had the problem, they locked out that side and continued on the stbd and on two water jets.
 

Oldgateboatdriver

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Chief Stoker said:
The ship has two cruise diesels and two gas turbines in a CODAG arrangement. Most likely the port and stbd main combining gearbox that input into two separate gearboxes, that in turn feed the four water jets.  There are two shaft lines involved with this and not separate gearboxes for each individual water jet. It appears that the port combining gearbox had the problem, they locked out that side and continued on the stbd and on two water jets.

OK. That makes sense, but if they still have a combined/two cooler of the Lube Oil as I described, you still have the possibility of cross-contamination, and in that case, the place where the problem first shows up is not necessarily the place that's the problem. In that case, it also makes sense to shut down everything until you can figure out the source.

And Chief, re: the "shafts" you may have noticed I put the term in quotation marks. That is because  what engineers will consider a shaft (and I know there are shafts involved between engines and gearboxes and gearbox to gearbox and gearbox to water-jet impellers) is different from the understanding that most other people have of the term: They usually think we refer to "the" shafts between the gearbox and the propellers on "normal" ships propulsion system.

I also note that T6, for instance, took from your post that the engine breakdown was out of the picture, but in a single combined oil cooling system, the source of contamination can just as much be an engine (bushings wear) as a gearbox (gear surface wear).

I grant you that we combine cooling systems less and less frequently, and I personally would expect a warship like the Freedom's to have separate lube oil cooling systems for the engines and the gearboxes.
 
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