Ten years ago this October, Fleet Readiness Center Southwest (FRCSW) marked the induction of its 100th legacy F/A-18 Hornet aircraft to undergo the Center Barrel Plus (CBR+) procedure.
For almost 30 years the commands innovative CBR program has ensured the readiness and prolonged the service life of the Hornet, the Navys first jet designed as a dual role attack-fighter aircraft.
The legacy A-D Hornet variants entered Marine Corps service 37 years ago and the Navy, one year later.
The initial CBR procedure was developed in 1991 when a crash-damaged F/A-18 with low 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 almost $46 million per aircraft, scrapping the aircraft for parts was the final option. Instead, the engineers and artisans of FRCSW challenged themselves to find a way to make the repair.
After a thorough examination, it was determined that replacing the center barrel was the most viable choice of procedure. In less than two years, the project was complete and at a cost of $4 million, it totaled less than 10 percent of the aircrafts replacement value.
The capability later evolved into the CBR + program, which addresses the fatigue life expectancy (FLE) of the legacy Hornets and includes replacement of the forward and aft dorsal decks, and the forward, aft, and keel longerons (structural beams).
Originally designed as a 6,000 flight-hour airframe, the legacy Hornets FLE reflects the usage history of an aircraft based upon stress-related factors affecting key areas of the airframe, such as the wing attachment points.
The aircraft also contain sensors that calculate its fatigue life.
The CBR occurs in aircraft with an FLE above .62. An FLE designation of 1.0, or 10,000 flight hours, indicates an aircraft that has reached its full fatigue life and slated for scrapping.
Aerospace manufacturer Northrop Grumman builds the center barrels and supporting kits that contain about 12 components, and thousands of fasteners are provided by Naval Air Systems Commands (NAVAIR) Central Kitting Agency in Orange Park, Fla.
FRCSW and FRC Southeast are the only naval maintenance facilities authorized to perform the CBR+ procedure.
FRCSW employs a staff of 52 that is comprised of artisans, supervisors, a production manager and the deputy program manager.
The CBR+ disassembly and assembly phases occur in Building 94, while the center barrel phases take place in Building 378.
Each CBR+ averages about 25,000 manhours at a total cost of $2.5 to $3 million per aircraft, according to CBR Deputy Program Manager Pedro Duran.
A point-of-use tooling project 13 years ago resulted in the creation of 16-foot aluminum work stands in Building 378. 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 per event.
As the legacy Hornet CBR+ procedures wind down, the command is turning its attention to the next Hornet variants: the F/A-18 E-F Super Hornets and the EA18G Growler, which also have a 10,000 flight-hour service life.
Unlike legacy Hornets, Super Hornets and Growlers do not have a third, or center barrel, section. Instead, the airframe is of a modular design.
"We have two new Super Hornet fixtures specifically made to remove and replace the different modules," Duran said. "Replacement averages anywhere between three months up to two years. So far, we have performed one forward fuselage replacement."
Meanwhile, he noted that the command has only three more legacy Hornet CBR+ procedures scheduled.
"Once completed, we will have pushed 152 aircraft through the FRCSW Center Barrel Program," he said.