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But a decade later in a program already fraught with setbacks, the design flaw reappeared. Now, about two-thirds of the military's fleet of Raptors are suffering from corrosion, prompting the Air Force to speed up the timeline for bringing the aircraft through Hill Air Force Base for maintenance.
"So the world's most expensive, most advanced aircraft is in the shop for repairs for something simple that someone figured out a long time ago?" said Nick Schwellenbach, national security investigator for the Project On Government Oversight.
"I'd like to say I was outraged, and it is outrageous," Schwellenbach said, "but it's all too common."
The Project on Government Oversight has exposed numerous other problems with the Raptor, which costs more than $130 million per plane - and nearly three times that when research, development and other costs are factored in.
Originally intended to be mission-ready by 1997, the Raptor has been plagued by cost overruns and delays. Billed as the most advanced fighter jet in the world, the aircraft has yet to fly a single combat mission.
It's unclear how much the corrosion issue will cost the Air Force to fix. Brig. Gen. C.D. Moore, who is leading production and sustainment efforts for the F-22 at Ohio's Wright-Patterson Air Force Base, said the "cleanup and mitigation" of already-identified corrosion problems could cost nearly a half-million dollars in labor costs alone. Corrosively resistant replacement panels - which won't be ready to install for another six months - will cost millions more to produce and the jets will have to be brought back to Hill or another maintenance center for installation - at a cost of millions more.
Moore downplayed the cost, however, noting it would be absorbed by the "overall sustainment plan" budget - which he said exists to handle unforeseen problems.
"We had already planned for 'over and above' work - you always do that," Moore said. "Every time you open up an airplane, you discover something."
But frustrating to Schwellenbach and other defense experts was the idea that this was not a problem that was simply discovered during routine maintenance - but one that had been identified and addressed in the mid-1990s.
At that time, the Raptor's development was already years behind schedule and critics in Congress, the federal Government Accountability Office and nonprofit watchdog groups were beginning to complain that the stealthy Raptor - first conceived in the mid-1980s at a time when U.S. military aircraft were finding it increasingly difficult to avoid detection by Soviet radars - was an uber-expensive Cold War weapon in a post-Cold War world.
Even as the Soviet threat had diminished, however, the Air Force and the Lockheed Martin Aeronautics Co., the lead contractor for the F-22 program, continued to push to improve the plane's "low observable" qualities.
As originally conceived, the Raptor was designed to have few exposed joints and edges - a characteristic that lowered the aircraft's radar visibility. But techniques that made the plane more stealthy - for instance, filling the seams of the access panels with a soft, rubbery putty - were not always best from the standpoint of corrosion control.
Alerted to concerns that the metals, paint and other materials used in and around the panels would interact in a way that would cause severe corrosion - particularly if moisture were to seep into the seams - Col. Kenneth Merchant, now a brigadier general and vice commander at Hill's Ogden Air Logistics Center, oversaw a change in design. Merchant left his assignment in 1997 believing that the problem had been addressed by a change that included switching the metal used in the panels from aluminum to titanium. The change made the Raptor, the twin engines of which produce a chest-rumbling 35,000 pounds of thrust each, negligibly heavier. It also made the aircraft slightly more vulnerable to radar.
Moore said the decision to overrule Merchant's change came over the course of several years as engineers sought to find "the right balance" between durability, performance and low radar observability.
"We thought we got it right," he said. "We understood there was a corrosion risk."
That irked Schwellenbach. "What's the point in it being more stealthy if it's in the shop?" he asked.
Phil Coyle, a senior adviser at the Center for Defense Information, observed that many of the efforts to make the F-22 more stealthy have resulted in unexpected and expensive delays.
"It's clear that maintaining stealth to the degree they were trying to do has been a problem and still is a problem," he said. Trading corrosion resistance for radar invisibility may have made sense when the U.S. military was trying to penetrate "the very tough radar defense of the Soviet Union," Coyle said. "But of course, the Soviet Union doesn't exist anymore."
For his part, Merchant said he believes everyone was acting in good faith when his change was countermanded.
"I don't believe there was anything untoward on anybody's part," Merchant said.
He said the "good news story" was the fact that Hill was able to stand up its depot maintenance center a year ahead of schedule to address the issue.
Considering that total costs associated with bringing the Raptor into fighting shape are now hovering around $360 million per plane, longtime Raptor critic James Stevenson says he doesn't see any good story.
In all, Air Force maintainers are working on 17 access panels - as small as several inches and as large as two feet. Four of the panels on the topside of the aircraft have been found to be most susceptible to corrosion and will be replaced - at a cost of $50,000 per aircraft, not including labor.
Although the Air Force has called that work "minor structural modifications," Stevenson doesn't buy it. "Depot work is not minor, by definition," he said.
But Stevenson said he was not surprised to hear the issue being minimized. "They always refer to their problems as hiccups," he said. "It doesn't matter if it is catastrophic or minor."