Inspectors say Hill Air Force Base is stripping and repainting F-16 fighter jets so often that "the structural integrity of the aircraft may have been compromised."

The Pentagon made the same complaint back in 1999, and recently decided to follow up to see if conditions had improved. Inspectors said problems remain with stripping planes too often with a high-powered stream of small, soft plastic beads.

Hill disagrees. In a written response to the Deseret Morning News, it says recent studies have shown the process is safer than inspectors assume. And Hill said it has found "no evidence of aircraft structural stress or fatigue failures" caused by it.

The concerns are revealed in a report, dated last November, by the Air Force Audit Agency obtained by the Morning News through a Freedom of Information Act request.

Back in 1999, the agency had complained that maintenance depots — including Hill's Ogden Air Logistics Center — stripped and repainted aircraft every time they came in for scheduled maintenance because customer wings "wanted aircraft to look new when they returned." Inspectors said then that had wasted $157 million in six years.

The agency in 1999 also complained that too-often stripping with plastic beads would cause structural fatigue and shorten aircraft life-span. It said planes should not be stripped more often than once every six years, and no more than three times in their life-span. It found that 96 percent of aircraft had been stripped more often than that.

The new report said Hill had "significantly improved oversight of F-16 bead blasting and painting frequency," but "some F-16 aircraft were still bead blasted too often."

Inspectors found that five of 43 F-16s they reviewed had still been stripped and repainted more than once every six years. (They looked at records for only a sample of the 500 or so F-16s that are repainted at Hill each year).

That suggested only 12 percent of planes are still being repainted more often than inspectors would like, compared to the 96 percent found in 1999.

Still, inspectors wrote, "The structural integrity of the aircraft may have been compromised. This is a repeat condition."

Inspectors also complained that "structural engineers were not inspecting the structural integrity of those aircraft that were bead blasted more than three times" in their life-span — which they said is required before additional stripping occurs.

Inspectors said the problems continued because base personnel did not always review maintenance records to see how often planes had been bead blasted, and because maintenance forms were not always accurate or complete.

However, inspectors noted that Hill had begun to use a softer plastic bead in the stripping process, and they said studies should be conducted on whether they may not cause as much damage as harder beads used previously — and whether time restrictions on stripping should be lifted or modified.