I’m sure by now everyone has
heard that the Navy’s newest LCS, the Milwaukee
What has not been reported
is that the recent breakdown of the LCS Milwaukee due to metal filings in the
lube oil system may have had its origins in an earlier incident during
construction and the current breakdown may have been avoidable. Here’s a description of the May 2015
construction incident as provided by Defense News website (1).
“The Milwaukee had been aiming for a delivery date in
August, but that's been delayed at least a month by a shipyard accident that
took place in late May in the midst of builder's sea trials — a series of
underway periods where the shipyard checks out the ship before the Navy runs
acceptance trials. …
The accident took place late one evening as the ship
was pierside in Marinette, trying to get ready to head back out in the morning.
‘We were basically looking at cleaning up a lube oil
system,’ North [Joe North, Lockheed's vice president of Littoral Ships and
Systems] explained. ‘We had an inadvertent start of the turbine that went to
the gear that spun the starboard shaft in the machinery plant between the
splitter gear and the forward gear.’ The shaft should have been decoupled so
the turbine wouldn't turn it. ‘So with no lube oil there, that is not the way
you want to run it. It was a very, very short time frame, less than a minute.’
But it was long enough to damage the splitter gear,
shaft bearings and other parts.
‘We were actually pretty fortunate there wasn't a
whole lot of damage in there,’ North said. ‘There were a lot of parts that
might have been scored or something or marked. We had them remachined, brought
back in, put the gear back together.’
Repairs have been completed, he said, and crews were
putting all the pieces back together to resume sea trials.
While the investigation is still being completed,
North acknowledged the accident was the shipyard's fault.
‘It was a procedural error, human error,’ he said.
The Navy is right in the middle of overseeing the
repair work.
‘We are pleased on the Navy side with the work we are
seeing and the progress that is being made,’ Rear Adm. Brian Antonio, program
executive officer for the LCS, said July 17 at the shipyard. ‘I actually went
down into the space and things are being put back together again. The shipyard
is doing the welding and the testing required to put the ship back to where it
was prior to the casualty.’ “
So, we have a construction
incident in which the splitter gear and other equipment was damaged by being
run without lube oil. The operation of
the gears (metal on metal) undoubtedly produced metal filings in the
splitter/combining gear assemblies. It
seems quite likely that the current breakdown due to metal filings in the
splitter/combining gear assemblies originated from the earlier construction
incident. It appears that the earlier
construction incident produced metal filings that were not cleaned out from the
splitter/combining gear system and those filings eventually accumulated in the
splitter/combining gear lube oil system, clogging the filters, and shutting the
system down.
 |
| LCS Splitter/Combining Gear System |
If true, this raises a lot
of questions. Why wasn’t the earlier
incident properly repaired? Any engineer
would have known there would be metal filings present in the system after the incident. Why weren’t they cleaned out?
Knowing that there had been
an earlier incident, why didn’t the Navy insist on much closer inspection of
the lube oil systems? The filings were
there the whole time and would have been readily evident on closer inspection.
Rear Adm. Antonio went into
the engine space. Perhaps he should have
sent an engineer into the space instead of conducting a public relations
exercise that accomplished nothing. What
was he going to see? Nothing.
The Freedom class has a
history of engineering/propulsion system breakdowns including lube oil system
issues. Why wasn’t particular attention
paid to the Milwaukee
Let me be quite clear about
this report. This is my speculation and
the link between the construction incident and the recent breakdown is not
confirmed. It is based only on a logical
assessment of the public information.
However, if the two incidents are not related, the co-incidence is
astounding.
Further, if the two
incidents are related the manufacturer should be responsible for the entire
cost of this breakdown.
Finally, if related, this
yet again demonstrates the Navy’s utter lack of in-house engineering competency
and oversight of ship construction.
(1)Defense News, “LCS Hits
Its Stride in Marinette”, Christopher P. Cavas, July 26, 2015 ,
I wonder if after the 'inadvertent' start they just ran the lube oil system and did not find any metal filings but when they then went out into the Atlantic the sea state bounced things up and down enough that the filings got mixed into the lube oil and shut things down
ReplyDeleteI also wonder at the lack of redundancy which allows contamination caused by a failure of one gear box to shut down the entire propulsion system which requires the ship to be towed
Does anyone have any drawings of the entire propulsion system?
Also what happened with the Navy Oil Analysis Program (NOAP) ? They are suppose to take regular samples and special samples after any suspected damage. They can find even tiny amounts of material and even tell what it comes from by the different amounts of various contamination. For example they can tell if a bearing is going bad because it has specific materials in it which if found in the lube oil will point to wear and damage.
DeleteDoes the low manning LCS even take NOAP samples? Did the shipyard?
Good questions for which I have no answers.
DeleteAre you reporting based on an actual examination of the gears, or just speculation? I ask this because in my experience that metal filing is a consequence, not a cause. Most likely was the gears were not machined correctly or incorrectly assembled. Removing too much material from teeth would cause the hammering on the tooth face. A second possibility was the bears were damages by vibrations in the gears. Either way, the problem did originate from the "accident" and as preventable with proper inspection, but I don't think the filings were left in the lube system when it reassembled.
ReplyDelete+
*-
If you read the post, you saw this sentence,
Delete"This is my speculation and the link between the construction incident and the recent breakdown is not confirmed."
So, that answers your question.
The filings were the cause of the subsequent breakdown in that they clogged the lube oil filter. The question posed in the post, and answered by my speculation, is where the filings came from. It appears logical to assume they resulted from the original incident in which the gears were run dry.
You also said
Delete"It appears that the earlier construction incident produced metal filings that were not cleaned out from the splitter/combining gear system and those filings eventually accumulated in the splitter/combining gear lube oil system, clogging the filters, and shutting the system down"
The problem with this is the assembly process calls for a flushing the complete lube oil system after the gear box is re installed. But that flushing will do nothing for any new filings created after the gearbox is put back in services. Which is why the filings found in the filter most likely were created during the run time after the Milwaukee was commissioned.
GLof, gotta disagree. If the filings were new, it means that there is a mis-toleranced fittings/gears that created new filings due to rubbing. If so, every LCS with the same gearing system would be suffering from filings in the system and that doesn't appear to be the case. No, the simplest explanation is the original filings never got cleaned out. While the reinstallation process may call for a complete flush/cleaning (do you know the process? do you have a written procedure for this or are you just speculating on what ought to be standard good practice?)it was probably just improperly done - just as the original incident should never have occurred but did. Design engineers can write all the procedures they want but if the hands-on guys don't follow them it won't make any difference.
DeleteThis one seems pretty clear.
If the parts were original cuts, (IE made with unworked metal)Then you be correct, but there is a give away in the press release.
Delete"North said.‘We were actually pretty fortunate there wasn't a whole lot of damage in there,’ North said. ‘There were a lot of parts that might have been scored or something or marked. We had them remachined, brought back in, put the gear back together.’"
That is when I think the damage was done. That why other gearboxs did not fall apart.
Oh as for my knowledge on gear boxes, it mostly with smaller industrial type that are normally replaces, not re built. But done my share of causal investigation for my employers back when, so I know about gear failures.
Ihe process of rebuild a marine gearbox come to me for a couple of oldtimers on naval discussion board, during one of JFK's major SUPSHIP inspection failure. They aim me toward a marine engineering handbook that I purchase a copy
of a read cover to cover.
GLof, remachining reduces the size of the part(s) being machined. That makes the tolerances larger (looser fit) and LESS likely to subsequently produce metal on metal filings because the metal is no longer rubbing on metal. So, where would the filings have come from?
DeleteMy interpretation is still the most logical.
I know you like to defend the LCS but this is not an indictment of the LCS. It's an indictment of the manufacturer's quality control and safety. It's an indictment of the Navy's NAVSEA group. It's an indictment of the Navy's engineering practices. It's not an indictment of the LCS. Nothing about the LCS, itself, caused this.
Accept the evidence and the logic until more or better information comes out.