Because of the advanced age of the fleet, ensuring airworthiness is a challenge for the SRG's maintenance personnel. The wing pivot points and the wing-carry-through boxes are presenting problems again: Although General Dynamics corrected the earlier weaknesses, the steel is starting to show its age. RAAF mechanics say it's a low-carbon alloy; despite high tensile strength, it's very brittle and prone to corrode over time.
Given the swing-wing design (that is, no wing spars to distribute loads, as a conventional aircraft would have), the loads are heaviest on the areas of the wings nearest the pivots and the WCTB. As the steel ages, those wing areas are more susceptible to stress cracks. To prevent that, mechanics have to tear down a wing (first allowing its fuel cells to dry completely). Then with a small piece of 320-bit aluminum oxide paper on the end of a finger, they reach inside and scratch away, re-profiling internal support assemblies to ease the loads on the area. "You usually spend a couple days just on one area," says a wing shop mechanic.
Other maintenance headaches involve air ducts, which are mounted outside the landing gear housing but with the bolts mounted inside the housing. The ducts break frequently and need to be replaced. "To get at them, you stand on the speed brake, put your arm through [the gear assembly], and twist around, and you're turning blind back there," says Sergeant Michael Tenaglia, who maintains engines and airframes. "You can't see it because your back's to it, so you hold a mirror up and look back over your shoulder."
Replacement parts aren't always available. Even though the RAAF spent about $100 million to acquire spares from the U.S. Air Force after the Americans retired their fleet, maintenance crews have sometimes had to refurbish old parts and have also cannibalized five F-111Gs to keep the rest of the fleet flying.
Avionics too show their age. The TFR, now in its third generation of technology, still fritzes out occasionally. And while the C models are now equipped with nearly infallible GPS receivers, the Gs still use inertial navigation, the software for which frequently needs updating, when it doesn't fail altogether.
Yet for a country that spends $6.9 billion—less than two percent of its gross domestic product, according to most recent figures—on its military, it is far cheaper to maintain an older aircraft than to replace it with something new, which would cost billions of dollars. Besides, says Dunlop, as well as about a dozen other RAAF officers, what else is out there?
Nothing like the F-111. Not really maneuverable enough to be called a fighter and several tons short of a big bomber's carrying capacity, the -111 nevertheless has its own special set of capabilities. Jim Rotramel puts it in perspective: "During my [final] flight I wanted to see how far we could go at low level, so we zig-zagged across the width of the state of New Mexico for an hour and a half at 550 mph. Our internal fuel weighed more than a combat-loaded F-16."
No wonder it was tough to find the F-111 an appropriate name.