The U.S. Navy has discovered that
part of the wings on their F-18E (officially the "F/A-18E/F Super Hornet") are
wearing out faster than expected. Instead of lasting 6,000 flight hours, the
portion of the wing that supports the pylons holding stuff (bombs, missiles,
equipment pods or extra fuel tanks) is now expected to be good for no more than
3,000 flight hours. The metal, in effect, is weakening faster than expected.
Such "metal fatigue", which ultimately results in the metal breaking, is normal
for all aircraft. Calculating the life of such parts is still part art, as well
as a lot of science. The navy will modify existing F-18s to fix the problem,
which is a normal response to such situations. Sometimes these fixes cost
millions of dollars per aircraft, but this particular fatigue problem will cost
a lot less to fix.
The problem does not occur with the older F-18s
(the A, C and D models) because, while they are also called F-18s, they are not
the same as the F-18 E, F and G models. That's because, when the navy decided
to build a replacement for the earlier F-18, they found they could get away
with calling it an upgraded F-18 model. Thus, instead of it being called the
F-24 (the next number available since the start of the Department of Defense's
standard designation system in 1962) it could be called the F-18 E and F. While
the F-18F looks like the original F-18, it is actually quite different. The
F-18E is about 25 percent larger (and heavier) than the earlier F-18s, and had
a new type of engine. By calling it an upgrade, it was easier for the navy to
get the money from Congress. In the early 1990s, Congress was expecting a
"peace dividend" from the end of the Cold War, and was slashing the defense
budget. The "F/A" designation was also invented, ostensibly to indicate that
the aircraft was a fighter (the "F") and light bomber (the "A" for "Attack").
There was a lot of commonality between the two F-18s, but they are basically
two different aircraft.