With a whistleblower lawsuit against Lockheed Martin grabbing headlines for making the startling allegation that the US Air Force's top-of-the-line fighter, the F-22 Raptor, has been supplied defective stealth coatings, further information is now emerging from  Pentagon sources that the F-22 programme is indeed the source of substantial worry for the defence establishment.

Internal documents, as well as Pentagon officials, reveal that Lockheed Martin's F-22 now requires more than 30 hours of maintenance for every hour that it spends in the skies. This adverse ratio effectively pushes its hourly cost of flying to more than $44,000, which easily outstrips the cost of keeping other fighters in the skies – those which the Raptor is meant to replace.

Seemingly lending credence to whistleblower ex-employee Darrol Olsen's claims, that the company knowingly used "coatings that Lockheed knew were defective," are reports that not only are these coatings susceptible to peeling off but also that they are vulnerable to rains and other abrasion. Olsen claims that Lockheed covered up its problem with defective coatings by applying 272kg (600lb) worth of extra layers.

Pentagon sources say that these problems have been bedevilling the aircraft since the mid-1990s. (See: Lawsuit claims Lockheed's F-22 Raptor has defective stealth coatings )

Local media reports reveal that even as most aircraft fleets become easier and less costly to repair as they mature, the reverse is the case with the F-22. On an average, the Defense Department acknowledged this week, just 55 per cent of the deployed F-22 fleet was available to fulfil stipulated missions in the period from October last year to this May.

The F-22 has never flown in combat missions over Iraq or Afghanistan.

A litany of complaints

The Raptor has become a contentious issue between the US Congress and the Obama administration with defence secretary Robert Gates halting further production of the $138 million aircraft, beyond the stipulated 187.

This is far short of what the USAF and the contractors had anticipated.

Defense officials in the know have been quoted in the media as saying that the aircraft can just about manage 1.7 hours of hassle-free flying before contracting a 'critical' ailment other point out that the Cold War-era conceived fighter has, so far, cost an average of $350 million apiece and are just not a priority in an age of small wars and terrorist threats.

The massive maintenance bills are also draining away air force funds urgently required for other projects. Former top Pentagon weapons testing expert Thomas Christie (2001-2005) has been quoted as saying that the plane's huge costs has resulted in the Air Force lacking funds to modernize its other components adequately. He said the force has "embarked on what we used to call unilateral disarmament."

According to Pierre Sprey, one of the founding members of the so-called ''fighter mafia'' – the group that conceived America's most successful modern combat aircraft, the F-15, the F-16, and the A-10 - from the beginning, the Air Force designed the Raptor to be "too big to fail, that is, to be cancellation-proof."

Prime contractor Lockheed farmed out more than 1,000 subcontracts to vendors in more than 40 US states, and Sprey points out that  by the time skeptics "could point out the failed tests, the combat flaws, and the exploding costs, most Congressmen were already defending their subcontractors' " revenues.

Media reports quote John Hamre, Pentagon comptroller (1993-1997), as saying that the DoD approved the plane with a very low budget as it knew projecting the real costs would have bounced the project on Capitol Hill.

"We knew that the F-22 was going to cost more than the Air Force thought it was going to cost and we budgeted the lower number, and I was there," Hamre told the Senate Armed Services Committee in April.

"I'm not proud of it," Hamre is quoted as saying in a recent interview.

The aircraft has undergone a plethora of problems, in line with the radical nature of its design it must be said. For the USAF, the sad part is that the problems have failed to stabilise in spite of near six squadrons already deployed in active service. 

With limited production commencing in 2001, the plane was "substantially behind its plan to achieve reliability goals," the GAO said in a report the following year. Structural problems compelled forced retrofits to the frame and changes in the fuel flow. Computer flaws, combined with defective software diagnostics, forced the frequent retesting of millions of lines of code, according to two Defence officials quoted in a local media report.

Stealth coating problems, which often require re-gluing small surfaces, as the coating peels off, take more than a day to dry. These facts have been culled from confidential data drawn from tests conducted by the Pentagon's independent Office of Operational Test and Evaluation between 2004 and 2008.

Over this four-year period, the Raptor's average maintenance time per hour of flight grew from 20 hours to 34. Stealth coatings alone accounted for more than half of the maintenance time, and more than half the hourly flying costs last year, according to the test and evaluation office.

While the Air Force claims that the F-22 cost $44,259 per flying hour in 2008, the Office of the Secretary of Defense said the figure was $49,808.

The F-15, the F-22's predecessor, has a fleet average cost of $30,818.

Sprey has also claimed that he was informed by engineers who have worked on the aircraft that because of Lockheed's use of hundreds of subcontractors, quality control was so poor that workers had to create a "shim line" at the Georgia plant where they retooled badly designed or poorly manufactured components.

"Each plane wound up with all these hand-fitted parts that caused huge fits in maintenance," Sprey said. "They were not interchangeable."

Lockheed denies such claims, however, and says "our supplier base is the best in the industry."

The plane's famed 'gold canopy' a million-dollar, radar-absorbing cause of envy for other fighter pilots has also caused problems. A stuck hatch imprisoned a pilot for hours in 2006 and, to date, engineers have been unable to extend the canopy's lifespan beyond about 18 months of flying time.

Ex-Pentagon official Ahern and Air Force Gen CD Moore, have both confirmed that canopy visibility has been declining more rapidly than envisaged, forcing $120,000 of repairs at 331 hours of average flying time, instead of the stipulated 800 hours.

The plane's first operational flight test in September 2004 saw it meet two of 22 key requirements and display a total of 351 deficiencies. In 2006, it fully met five, and in 2008 when the sixth squadron was fully deployed, the Raptor had fully met seven key requirements.

Pentagon officials stress that the F-22s are on track to meet all its key performance parameters by next year.