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/ / / / NPEO 2014 Volume 2 Issue 2 (March)

Overhauling Aircraft Carriers

As the only ship platforms in the U.S. Navy designed to last a half-century in service, America’s nuclear powered aircraft carriers play a unique role not only in fleet inventories but also in national strategic planning. Ensuring the relevance of these transformational platforms for their entire 50-year service life is supported by a lynchpin program known as refueling complex overhaul (RCOH), a mid-life overhaul for the recapitalization of Nimitz class aircraft carriers.

The 44-month maintenance period, which begins around the 23rd year of service, extends the life of a Nimitz class carrier by modernizing the ship’s combat and safety systems and equipment while also refueling the ship’s nuclear reactors. Additionally, an RCOH provides an opportunity to perform underwater hull inspections and other maintenance related evaluations that cannot be accomplished while the ship is waterborne. The RCOH cycle provides sufficient time to perform more extensive propulsion plant repairs and testing than is possible during shorter scheduled maintenance periods.

The first RCOH, performed on USS Nimitz (CVN 68), began in 1998. Most recently, 2013 witnessed completion and re-delivery of the fourth successful RCOH, USS Theodore Roosevelt (CVN 71), by Newport News Shipbuilding (NNS) (a division of Huntington Ingalls Industries) in late August as well as the start of RCOH at NNS on USS Abraham Lincoln (CVN 72) in March.

Planning and executing the multi-year RCOH process involves Program Executive Office (PEO) Carriers, Naval Reactors, Naval Sea Systems Command (NAVSEAP), Supervisor of Shipbuilding Newport News, Huntington Ingalls Industries, Naval Air Forces and, of course, the ship and her crew.

Within that team structure, PEO Carriers has the responsibility for coordinating planning, budgeting and execution of the RCOH. “The RCOH has been, and remains, probably the most demanding industrial task that anybody has ever undertaken,” offered Rear Admiral Thomas J. Moore, U.S. Navy PEO Carriers. “I would argue that it is much more challenging than new construction. It’s a lot harder to take an existing ship apart and go do what we do in some ways than building it from the ground up.”

Characterizing the process as being similar to “open heart surgery,” Moore pointed to a number of lessons learned and process improvements that have been implemented over the first five ships.

“The substantial change that has occurred since we did Nimitz is the recognition that this is an opportunity, while the ship is in there, to get a lot more modernization done on the ship,” he explained. “So if you were to look from a historical perspective at the amount of modernization that we did on Nimitz, for instance, and then trace that through [CVN] 69 [USS Dwight D. Eisenhower], 70 [USS Carl Vinson], 71 [USS Theodore Roosevelt], to 72 [USS Abraham Lincoln], you would find that Lincoln reflects the largest modernization package that we have to date.”

“You have the ship captive for 44 months to get through the critical path work of refueling the ship and getting the propulsion plant put back together and tested,” he noted. “So once the ship is delivered back to the fleet, we really want to take maximum advantage of the fact that the ship has been offline for four years—and get it back to the operating fleet.”

A cursory look at the numbers can be deceiving. For example, the first RCOH, performed on USS Nimitz, was done in just 39 months, the least amount of time of the first five CVNs. However, at the completion of that RCOH, Nimitz was sent back to the West Coast and taken offline again for an upgrade to the combat systems and C4I suite.

“So what we’ve done is address the modernization [in RCOH] so that when the ship comes out she is essentially the most combat ready aircraft carrier we have,” Moore said. “You’ll see that the modernization package on Lincoln is the biggest as a result. We want to fit that work into the 44 months and we think we will be able to do that.”

Moore said that another processing change involved the fact that early RCOHs were followed by four to six months of ship shakedown and a subsequent four to six months of post shakedown availability in a shipyard.

“Starting with CVN 71 there was a concerted effort to see how we could get the ship back to the fleet sooner so that the combatant commander can use her quicker,” he noted. “So we basically went back and did a ‘lean event,’ and decided that we could incorporate a lot of the PSA/SRA [post shakedown availability/selected restricted availability] work into the RCOH baseline length of 44 months. And a lot of that is also modernization stuff. So we have basically built a program where we can reserve space and weight in certain spaces and then get the latest and greatest technology, particularly in the C4I computer world where the technology turn circle is pretty tight.

“The net result was that CVN 71, which we delivered in September, has essentially already done flight deck certification and has been turned back over to the fleet commander to start into her workup cycle. She will deploy about 16 months after the end of her RCOH, and in reality she could have gone quicker if the fleet commander had wanted her to do that,” he added.

“Relatively speaking, RCOH is a very efficient way to modernize the carrier, not just the refueling piece,” echoed Chris Miner, vice president of In-service Aircraft Carrier Programs at NNS. “In the 50-year life of an aircraft carrier, we can perform 35 percent of all the maintenance and modernization of that carrier in basically a 44-month period. If you think about that, it’s an extremely efficient way to re-establish/re-constitute that carrier—basically recapitalize that carrier’s value for the next 25 years. And to do it in a very short period of time is a very efficient way to do that work.”

Outlining the level of effort over a 44-month RCOH, Miner pointed to more than 20 million man hours of work by a shipyard workforce that peaks at about 4,000 ship builders, along with another 2 million man hours of work is performed by the ship’s force (crew) and several million man hours by other Navy sub-contractors.

“It’s a total team effort relative to the ship’s force, the Navy and the shipyard, but Newport News Shipbuilding is responsible for the integration of all of that work and getting it done in that 44 month period,” he said. “During that period we refuel the two nuclear reactors—that’s a core piece of it. We also strip down the catapult and the arresting gear—all the equipment that is used to launch and recover aircraft. We strip those down and refurbish them completely and rebuild them back to basically new construction/brand-new specs. That’s after 25 years of wear and tear. We also go through thousands of tanks and voids that have been used to store fuel, potable water or ballast water for the ship. We open those when a ship is in drydock. It sits in drydock for approximately 18 months when the ship arrives. And we refurbish those tanks and get them ready for refilling. We pull the shafts and refurbish the shafts and propellers. We overhaul literally thousands of pumps and valves throughout the ship. We upgrade their combat systems, navigation systems and all the electronics.

“When she is done she is as capable as a brand-new carrier being delivered,” he added.

While acknowledging the extreme complexity of all aspects of RCOH, Miner said that the greatest challenges lie in the unknowns about a carrier’s specific arrival condition.

“Although we spend 30-36 months planning for RCOH execution, including what we call pre-arrival ship checks where we will send people out to the ship to basically inspect and identify as many things as we possibly can that need to be worked on, the challenge is that for a 25-year-old ship there are some things that you just can’t see until you take them apart,” he said. “We have a lot of inspections and a lot of disassembly that we do to identify any of the ‘hidden issues’ that might not be a problem today, but when you are reconstituting the ship for another 25 years of service or bringing it back to a point where it’s just as reliable as it’s been for the first 25 years, the challenges are that we do identify a lot of additional work that we need to do as we are going through the RCOH.

“We have become very good at being flexible to respond to those challenges and that additional ‘emergent work’ that is identified,” he continued. “We have a very robust technical engineering staff here and an organization that supports us, and obviously from our perspective the greatest shipbuilders in the world that have done this before. So they are able to quickly investigate and to do the analysis of the problem and provide the technical solution. We’re also very good at determining what materials are available, what skill sets are available, and then integrating that work into the baseline schedule.

“But I don’t want to make that sound easy,” he cautioned. “That’s one of the largest challenges we have on the RCOH—the identification of new work during the period that we are actually trying to execute that 20-plus million man-hours of work that we have planned for.”

Miner pointed to a number of other actions and procedures that have contributed myriad efficiencies to the RCOH.

“We looked at new tooling and new processes,” he summarized. “We worked with the customer to ensure that all requirements are ‘value added.’ We changed the sequence of things and looked at things like how we bring the work and the dock together for things like refurbishing them and bringing them back. We have improved our processes for cleaning systems. We have improved our weld processes. We’ve improved our machining processes. All those types of things have added to benefits that we have done in the past. And we will continue to look at that in the future.

“It’s also important for me to highlight one of the huge benefits of the RCOH program as a whole,” he added. “The RCOH program basically follows the same sequence in which the carriers were built. And it’s a heel-to-toe program. So as we were actually executing the RCOH here at the shipyard on Nimitz, we had people planning for the next RCOH on the Eisenhower. When the Nimitz was delivered and the Eisenhower was delivered immediately behind it we could take those same people that just did the work on the previous carrier and move them to the next carrier, taking with them those lessons learned and working to improve processes, improve cycle times, reduce cost and get more work into a smaller period of time.”

Moore was quick to recognize the importance of efficiencies implemented to date as well as continuing budgetary pressures. Although the introduction of greater modernization elements in RCOH has “skewed” the cost curve to some extent, he pointed to “a concerted effort underway, in particular for CVN 73, to start tipping that cost curve back over, so that I can get the same product out the door at a lower price—and at the same time still allow the company to make a reasonable profit.”

“To their credit the cost performance on the RCOH program has been very, very good,” he said. “The way we measure cost performance—the cost performance index—is a bit above 1.0 on the previous four RCOHs. And I would tell you that you would be hard pressed to find a multi-billion dollar program anywhere in the world that has cost performances better than that. So a lot of credit goes to the company for doing what is very demanding and challenging work and performing that well from a cost performance standpoint.”

Service participants point to the success of the RCOH program in ensuring that the venerable Nimitz-class still has 250 ship years remaining before the USS George H.W. Bush (CVN 77) retires in 2059. Additionally, while RCOH is currently focused on Nimitz class CVNs, the Navy’s long term plans project a similar RCOH on the USS Gerald R. Ford in the 2039-2040 timeframe. ♦

 

Last modified on Thursday, 03 July 2014 10:47

Additional Info

  • Issue: 2
  • Volume: 2
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