Milestone in Innovation: FRCSW Completes 100th F/A-18 Center Barrel Plus

Fleet Readiness Center Southwest (FRCSW) celebrated a milestone in naval aviation maintenance this fall, with the completion of its 100th Center Barrel Plus (CBR+) procedure to a legacy F/A-18 Hornet fighter.

The initial procedure was created in 1991 when a crash-damaged F/A-18 aircraft with minimal flight hours was brought to FRCSW (then Naval Aviation Depot North Island) for analysis. The area damaged was the center fuselage section – the center barrel – where the wings and main landing gear attach.

With a price tag of close to $46 million per aircraft, scrapping the plane for parts was deemed the final option. Instead, the engineers and artisans of FRCSW were challenged to find a way to make the repair. After a thorough examination, it was determined that replacing the center barrel was the most viable option. In less than two years the project was complete, and at a cost of $4 million, it totaled less than 10 percent of the aircraft's replacement value.

The capability later evolved into the CBR+ program, which addresses the fatigue life expectancy (FLE) of the legacy A-D Hornet aircraft. The FLE reflects the use history of an individual aircraft and is based upon stress-related factors affecting key areas of the airframe, such as the wing attachment points. An FLE designation of 1.0, for example, indicates an aircraft that has reached its full fatigue life.

"The F/A-18 was originally designed with a 6,000-hour-flight life. But the aircraft also go on a 1.0 FLE. The plane has sensors that calculate its fatigue life," CBR+ deputy manager Walt Loftus said. "So, you may use up to the fatigue life without having the flight hours. The airframes weren't getting to the full fatigue life; they were getting about 20 percent below that."

The CBR+ also differs from the original center barrel replacement in that the forward and aft dorsal decks, and forward, aft, and keel longerons (structural beams) are replaced.

Aerospace manufacturer Northrop Grumman builds the center barrels, and corresponding kits that contain about 12 components and thousands of fasteners are provided by the Defense Logistics Agency in Jacksonville, Fla.

"The CBR+ can only be done once to an aircraft," Loftus said. "In fact, the first one we sold in 2002, already used up its fatigue life and is here to be scraped out."

FRCSW and FRC Southeast are the only naval maintenance facilities authorized to perform the CBR+ procedure, Loftus noted.

"We have 110 artisans assigned to the program phases of disassembly, assembly and sheet metal phases, which are the majority of the work. Each CBR+ averages about 25,000 manhours at a total cost of $2.5 to $3 million per aircraft," he said.

FRCSW gained the $1 million savings per aircraft since the first center barrel procedure through AIRSpeed projects that targeted cost structures such as turn-around time and point-of-use tooling issues.

A point-of-use tooling AIRSpeed project in 2007 resulted in the creation of three 16-foot aluminum stands in Building 378 where the CBR+ procedure is done. The two-tiered stands enable work from atop and below the aircraft and provide direct access to materials and tools used by sheet metal mechanics, saving approximately 2,000 manhours.

FRCSW completes about 14 CBR+ procedures per year.

"No Super Hornet (F/A-18 E and F models) has had a center barrel replacement done yet," Loftus said. "But we have one here which may possibly need the procedure. The program engineers are in the process of looking at it."

"Meanwhile, there's about 435 legacy Hornets in need of having the CBR+ done, and between us and Jacksonville, we're not even half way there yet," he added.

The 100th CBR+ aircraft was inducted in October 2010, and delivered on November 18, 2011 to Marine Fighter Attack Squadron 323, based at Marine Corps Air Station Miramar.

The CBR+ program is currently scheduled to end in 2017.

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