This is interesting, A-10 Warthog father, F-16 Viper co-designer and longtime F-35 Joint Strike Fighter hater, Pierre Sprey has come out saying that the glues used to fasten F-22 Raptor’s stealth coatings to the aircraft’s skin are responsible for the spate of hypoxia-like symptoms suffered by its pilots (it’s getting so bad that we can almost say that Raptor jocks routinely suffer hypoxia).

Normally, I’d be skeptical of the the claim. However, Sprey says the glue, made of classified chemicals and is routinely reapplied to the jets, emits toxic gasses when the jet is travelling at Mach 1.6 and above. Guess who recently said they suspect the Raptors unparalleled mix of maneuverability, operating speeds and altitudes may have something to do with the problem? The U.S. Air Force.

Here’s what Gen. Janet Wolfenbarger, chief of Air Force Materiel Command, told lawmakers last month:

“We have some recent data that we are starting to believe, we are coming to closure on that root cause,” said Wolfenbarger during a May 8 Senate Armed Services Committee hearing. “We’re realizing that we operate this aircraft differently than we operate any of our other fighter aircraft, we fly at a higher altitude, we execute maneuvers that are high-G at that high altitude and we’re on that oxygen system at those high altitudes for periods of time.” “I’m not ready to say yet that we’re ready to declare a root cause,” she added.

As we said at the time of Wolefenbarger’s comments, the Air Force has been studying this problem for years and hasn’t been able to find a cause — despite enlisting the “best minds” from DoD, NASA, academia and industry to study the issue, according to Wolfenbarger. The fact that the F-22 operates at such extreme (possibly record-setting) levels beyond what other fighters — including the Navy’s F/A-18E/F Super Hornet that uses a similar On-Board Oxygen Generating System (OBOGS) as the Raptor — may explain why no one has been able to diagnose the problem.

Now here’s what Sprey told the Panama City News Herald about the F-22’s adhesives and its extreme performance:

Sprey said when the F-22 reaches speeds above Mach 1.6, which is about 1,200 miles and hour at sea level, the adhesive sets off gases that can cause the same symptoms of dizziness that have plagued the F-22 pilots. When the F-22 is in for repairs to its “stealth coating,” the adhesive is re-spread across the plane. “The adhesive has to be reapplied,” Sprey said. “When it is, it increases the risk to the pilots.” According to Sprey, the pilot is exposed to diisocyanates, which are found within the polyurethane glues that comprise the stealth coatings, at a number of times because the adhesives are reapplied in the upkeep of the plane. Sprey said diisocyanates are well known as an industrial hazard that can cause both severe lung and neurologic problems. But, [Air Force Spokeswoman Heidi Davis] said Sprey’s theory cannot be considered a leading line of inquiry at this point because it would need to be reconciled with contrary evidence related to the absence of toxins in life-support system components, cockpit air samples, or post-incident pilot blood samples. Sprey vehemently disagreed. He said polyurethanes are used in the Lockheed Martin stealth coatings, which also contain diisoycanates, and are one among several potential sources of poisoning of pilots that Lockheed and the Air Force should have been testing for toxicity long before they flew the first F-22. The Air Force said diisoycanates have not registered in the blood of F-22 pilots.

Sprey thinks the service won’t acknowledge that the glues are behind the problem because it would mean a costly refit of the 180 or so Raptors.

Dealing with the F-22’s glues, which provide the F-22 its stealth, would mean a “major rebuild of the airplane,” Sprey said. “The F-22 and the F-35 are three-fourths of the Air Force budget, and that is what is at stake,” he said.

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