A section of wing cut from aircraft 69-0004 at Robins AFB, Georgia, was used in a test for hidden corrosion by cutting apart a retired C-5A, confirming that the C-5 airframe was ready for another 20 years of service. The C-5 uses a wet wing, meaning the wing itself serves as the fuel tank rather than containing rubber fuel tanks like earlier aircraft. Each wing has six separate tanks that can feed fuel to any engine through pumps and valves. The wings are milled from solid 3-inch-thick aluminum billets to reduce places where leaks can occur, and fasteners that penetrate the tank have tapered bodies that resist leaking when the wing flexes in flight. Baffles inside the fuel tank prevent fuel movement during flight that could upset the aircraft's balance. The C-5 has 12 internal wing tanks with a total fuel capacity of 51,150 gallons, enough to fill 6 1/2 regular-size railroad tank cars, and a full fuel load weighs 332,500 pounds.