NAVAL AIR STATION NORTH ISLAND, Calif. –
FRCSW Shop Services F/A-18 Hornet Fuel Cells
Much of the maintenance on F/A-18 Hornet fighters that is completed by Fleet Readiness Center Southwest (FRCSW) artisans requires disassembly of the aircraft to access its various components and systems. One area of the airplane serviced is found in an extremely confined space: the aircraft’s fuel cells.
The fuel cell is located behind the cockpit, and accessed through a 17-by-12 inch hatch. Once inside, artisans remove and install the fuel bladder and work among the cell’s components.
The FRCSW fuel cell shop maintains all four of the airframe’s fuel tanks and one vent tank which serves as an overflow. Areas of the left and right hand wings where fuel is held and transferred are also serviced by the shop.
Evaluation and examination (E&E) personnel assess the cell’s components to determine if they are in need of minor repair, need scrapped out, or may go directly to kitting.
Approximately 10 percent of the shop’s workload is resolving fuel leakage issues that are found during an aircraft’s induction. The remaining workload is done for maintenance purposes or modifications.
One modification about six years ago, for example, targeted corrosion issues within the number two and three fuel cells.
The number four fuel cell is the largest and holds more than 500 gallons of fuel. Installation of that cell requires three artisans, while the remaining cells require at least two artisans, one of whom serves as a safety observer to the cell entrant.
The fuel bladders of legacy Hornets are made of a thick durable rubber, while the newer Super Hornet bladders are made of polyurethane. Though less durable than the legacy bladders, the thinner Super Hornet versions are cheaper to make, and easier to fold and work with.
Prior to bladder installation, fuel cells are equipped with anti-friction tape that covers all edges and corners to protect the bladder from rubbing against the cell. The procedure may take up to five days to complete.
Foam padding is also installed to prevent the bladder from rubbing against any metal. However, depending on what is removed for metal work access, foam padding may remain, which can save up to four days of prep work before installing the bladder for assembly.
After the cell is prepped, artisans lace the bladder to the wall to prevent sagging so it won’t interfere with components inside of the cavity when operating. The process takes about one day.
Next, before the fuel cell’s remaining components are installed, the bladder’s fittings are capped off and the unit is filled with air and monitored for signs of deflation.
If a leak is detected, artisans usually repair or replace the o-rings or replace the bladder entirely before the aircraft is fully fueled and delivered to the test line.
Fuel cell personnel must be finished with the aircraft before it continues through assembly. Power runs, checks tests and operations are not possible with an artisan working in the cell.
A Green Belt project three years ago that targeted production and readiness issues revamped completion of the fuel cell maintenance process to about 14 days.