F-16 Co-Designer Claims F-22’s Glues Causing Hypoxia

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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61 Comments on "F-16 Co-Designer Claims F-22’s Glues Causing Hypoxia"

  1. Hmmmm new stealth glue……or pilots dying? hmmmmmm tough choice

  2. The body that handles MDS sheets won't even acknowledge that isocyanates are harmful in the United States. Polyurethanes and isocyanates are so ubiquitous in everything, that if isocyanates were actually recognized as extremely harmful, it would affect many industries and probably the economy.

  3. Better living through chemistry.

  4. I have no idea what diisocyanates are or what polyurethane glues consist of, but the only part of this article that stuck out to me was this:

    "Dealing with the F-22’s glues, which provide the F-22 its stealth, would mean a 'major rebuild of the airplane,'"

    "The F-22 and the F-35 are three-fourths of the Air Force budget."

    The USAF is seriously screwed up if it's going to risk pilots lives and extremely classified technology in malfunctioning jets to save itself embarrassment and so it can buy more aircraft that haven't been fully tested. We should definitely look into this. It may require the USAF to kill F-35 funds to make the F-22 usable. We already bought 180 or so F-22s at $150 million a piece so they should take top priority. The F-22 already went through production so it's obviously the better one to have. If there is not at the very least an investigation into the stealth glues on the F-22 as a cause of the problem then I think our USAF leadership should be fired and replaced.

  5. If its toxins from the glue, can someone tell me why they need to rebuild the entire fleet when they could just install new air filtration systems? Hate to break it to y'all but toxins are common place on aircraft, heck, JP-8 will strait F you up if you arnt careful…… Ya it could be the cause, but the solution is not rebuilding the entire fleet, thats just BS. If its the glue, then a filtration system should eliminate the fumes and toxins.

    Ive been saying till im blue in the face, the Air Force has a vested interest in making sure this thing can fly. They will find a solution but knee jerk reactions, to what could be a simple fix, is not the way to go. Now if they determine its serious, then ya, sure lets look at the alternatives but for all we know its a $.20 o ring that keeps failing……

  6. Ace in D hole | June 21, 2012 at 1:16 pm | Reply

    amen DGR this guy trying to sell his BS idea of the glue to put his name out threr and is just plain wrong..I work with these aircraft everyday and it aint the glue baby

  7. Sad to say whatever is making the problem it'll take a major overhaul of F-22 fleet to fix. Id say build new raptors with te fix and overhaul current one BUT thats not happening since the Raptor is DOA on production.

    I do laugh and say is the glue made in China????

  8. CFR 1910.1200; The purpose of this section is to ensure that the hazards of all chemicals produced or imported are classified, and that information concerning the classified hazards is transmitted to employers and employees.

    Isocyanates have numerous uses but few are commonly applied at temperature of the heating levels of Mach 1.6 and above. This implies an ability to contaminate the breathing air or cockpit pressurization systems, thus introducing the chemical into the obogs or thru the pilots skin surface. This chemical exposure would be reduced at slower (lower temperature) flight conditions or as the lower presence of the chemicals in an older (dated) applications. How diisocyanates/ polyurethanes "gasses off" and contaminates either system is a question for the hydraulic studies of both the pressurization system and the obogs (possibly both).
    Re-skinning the plane is not required if it is possible to remove the chemical from the air systems or to route the air supply from a clean (or cleaner) source. Hmmmmm………..

  9. But the military already told us what the problem is…pilot error! Support the troops!!

  10. "The F-22 and the F-35 are three-fourths of the Air Force budget."

    Just thought about this. The USAF consumes its fair share of the defense budget, but you mean to tell me the 3/4 of it go to a fleet of about 180 aircraft and a strike jet that hasn't been built to production standards yet. That legitimately surprises me. Stealthy jets are REALLY expensive. Much more expensive than I previously thought.

  11. So . . . our pilots are sniffing glue?

  12. So its the glue used to re-bond the stealthy coating after being serviced and also in the assembly line. F22 Lockheed Martin Stealth…..F35 Lockheed Martin Stealth….So did anyone think to include the F-35 in this group that uses this glue? So… IF… it has the same glue will this not mean even more money has to be sunk into it? And more delays? OMG. I want this damn plane flying already. I am dual citizen US/Can and not only think it is a real cool air-frame but it is high time we underwent a force modernization like this. However….already on the tipping point, this could kill it in the Canadian public's eyes. Damn.

  13. so it was the bio-med, nanotech skin coating … wow, whodathunkit?

  14. meant: biological-mechanical (ALIVE & patented) "stealth" nano-thechnology skin coating

  15. . . .aand I can't even spell!!!

  16. tribulationtime | June 21, 2012 at 2:50 pm | Reply

    I remenber a similar remark about F-16I israelies from Israel Air Force, I mean a oficial comunication. Pilots report headache, breath troubles, etc.

  17. I stil think it could be low pressure created at the engine intakes. Remember that they said ground crews close to the plane were affected too but that may not be the case if it were the glue unless it was still hot from a flight. However, it would apply to them if the engines were running. If they have ruled this out, I haven't heard it. P.S. Be careful not to say the seven letter word for the compartment where the pilot sits. It seems to get automatically bleeped out….cockpit.

  18. elmondohummus | June 21, 2012 at 4:14 pm | Reply

    "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."

    That's not trivial. If the "glue fumes" released at supersonic speeds are genuinely the cause of the problem, where are the actual chemically measurable effects of that?

    Now that said, yes I would freely admit that the lack of resutls Ms. Davis is invoking could be due to incorrect testing. The case of Gloria Ramirez:

    … definitely opens the door to that possibility… (cont'd)

  19. elmondohummus | June 21, 2012 at 4:14 pm | Reply

    (… cont'd)

    However, the tests not finding evidence of diisocyanate contamination cannot simply be dismissed. Whatever the explanation is that eventually comes from the investigation, it *MUST* explain that, too. Anyway, my overall point is that whatever study that the AF did to lead Ms. Davis to make the statement she made cannot be ignored. It might be flawed, or it might simply not be sufficient, but it cannot be ignored because it might also be the data that falsifies the diisocyante theory. All data must be examined, and ignoring the lack of toxins to believe it Sprey's theory would not be solid science.

    The good thing about Sprey's explanation is that it's falsifiable. Just hypothesize more tests that can be done based on the presumption it's the glue and go from there. For example I'd be damn interested to see the results from sticking a sample of that adhesive on a plate into a supersonic wind chamber would be. It's testable. So hopefully the AF will go in that direction.

  20. How does glue applied on the exterior of a pressurized air plane get into the interior through the OBOG system? If this is the problem then a better filter like an earlier poster said or compressed oxygen backup should fix it.

  21. Somehow the pilots flying Lockheed’s original stealth aircraft survived the outgassing of similar adhesives and coatings from Mach 3+ flight. Read the AFMC CC’s statement again. The Combat Edge ensemble was intended to allow F-22 pilots to operate and maneuver at higher cockpit altitudes without a full pressure suit. The air mix being delivered and the lung’s ability to process it in that environment is a far more likely explanation for what’s going on and why the AF/contractor team hasn’t been able to nail it down. What Gen Wolfenbarger seems to be saying is that’s where the investigation is leading them.

  22. So, ditch the OBOGS and go back to LOX? Seems cheaper than replacing the adhesive for all of the RAM…

  23. This makes no sense. How could such a high tech plane allow toxic fumes to leak inside the cockpit? I'm sure internal pressure and speed alone would make sure that doesn't happen. And unless the pilot is flying without the mask on, chances are that any fumes he sniffed could be the hot wing belched gas from lunch.

    But if you think the F-22's skin is "glued" together, I could sell ice to the Eskimos.

  24. Now we heard and read the F-22 malfunctions, does these have the manufacturer's warranty?

  25. If the problem is coming from the glue on Lockheed Martin Jets, I dont understand why they are not going out of their way to find a fix? Surely that is bad business for them, seeing as boeing is doing everything is can to build reliable and great planes, not to mention on time and to the original budget. Bad business lockheed martin!

  26. im no fan of these "stealth crates" but, the glue cant be that new…..

    i still think its the engines.

  27. That guy knows more about aircraft than I do.

  28. ANGELO NICOLOSI | June 22, 2012 at 6:47 am | Reply


  29. USAF MX Chief | June 22, 2012 at 9:10 am | Reply

    T.M. you are incorrect regarding the MSDS (Material Safety Data Sheet) system not recognizing isocyanates as harmful to the human physiology. Please read this MSDS: http://tinyurl.com/7ddqynb

  30. USAF MX Chief | June 22, 2012 at 9:21 am | Reply

    T.M. you should also review this MSDS on Toluene Diisocyanate: http://tinyurl.com/6sk6avp
    This compound is commonly used as a solvent in surface coatings and other surface preparations (i.e., paint, primers, etc.)

  31. Oh Christ….are some of you saying that the Raptor has been cancelled by the Air Force?…..to be scrapped?……what about the F-35?…..

  32. What's the RCS penalty if you drop the coatings?

    Debating if it would make sense to keep part of the fleet with coatings and some without. For instance, Alert 5 aircraft would be ready to go with stealth coats, aircraft for home defense on CONUS and training flights wouldn't need them.

  33. Interesting article. Food for thought – I recently read an article where some of the ground crews were reporting similar symptoms when working within the immediate vicinity of running Raptors. Could the constant re-application of this coating, or the process used for re-application, also be the cause for those complaints as well?

  34. I thought the F16 was the Falcon, not Viper.

  35. Nasty fumes from glues, paints, etc., can find their way into, (or not get out of), all sorts of places. Large temperature swings can cause inadvertent internal pressures or vacuums in equipment. (Think of a simple Ball canning jar). Let me give you an example. I used to work in Avionics for MAG-39 AIMD at Camp Pendleton in the 80's. Many times we would smell cigarette smoke or engine exhaust or other chemicals when we opened up supposedly sealed electronic devices. Turns out the large temperature swings in the supply buildings, flightline, etc., was actually sucking in fumes at night when it got cold! It was more common in older equipment where the sealing was not 100%. Most of these fumes and gases don't really disappear, they mix with the air and are spread out to the point where they are not detectable. Since I got out of the service, I have been a construction electrician. Many times we deal with fumes that are sometimes decades old that are trapped in sealed spaces. PVC glue fumes from underground PVC piping are the most common. The pipes are glued, placed in trenches and backfilled before the glue has set, and the fumes can linger for years if trapped by water, etc. Methane gas can also leak into these pipes. Unlike when I first entered the trades in the 80's, we now always check for fumes and oxygen levels before entering enclosed spaces.
    Perhaps the OBOG system is not compatible with these fumes. Since the OBOG system is not an oxygen generator, but an oxygen CONCENTRATOR, maybe it is also concentrating these fumes. Maybe the oxygen produced is contaminated, OR, the oxygen concentration sensors are affected by the fumes and make the OBOG system think it is making enough oxygen when it is not.

  36. If adhesive glue fumes are suspected of causing F-22 hypoxia, I suspect the USAF has taken blood samples from F-22 pilots immediately after landing, for a testing program. Of course, anything found is highly classified, so exactly what, if anything, has been found remains unavailable to we, the public. I hope that this is the source of the pilot hypoxia, because the "fix" would be, should be, straight forward. That said, nobody should jump to any premature conclusions.

  37. Don't worry about the fumes;
    Equip some acft with Full chemical gas masks, augmented with Oxygen when required and see what the results are. You don't have to be a rocket scientist to figure that out.

  38. Sorry but the editors of this column should comment immediately when decidedly false info is spouted. Case in point, the "3/4ths of USAF budget going to F-22 and F-35 combined." Doesn't pass the common sense test. Check cost of manpower, health care, and pensions! Another case is blaming upper USAF folks for killing F-22. Try Congress instead because they allocate the monies for everything.

  39. Hypoxia is a strange animal. Just the suggestion of it can cause it. My navy flying experience saw numerous cases of this, especially when pilots flew new-to-them planes, stressful situations, and any night flying. The body tenses, and forgets to breath. When concentration is very acute, the same thing happens. Add high G maneuvers and continuous turns in 3-dimensions and you induce hypoxia.

  40. Even if the stealth coating was emitting a gas, I'm not sure how it would get to the pilot. The F-22s OBOGS makes oxygen by taking bleed air directly off of the engine and then passing it to the pilot within a closed system and the pilot has his mask on all the time in flight. Also doesn't make sense that the pilot's blood wouldn't test positive for the gas……….

  41. Why not a stand-alone, dedicated system of O2 supply, i.e. tanks, instead of a generation system for O2?

  42. I missed the LOX comment above, same concept!

  43. Probably it best to send it back to the manufacturer to fix it, exchange for a new model or make it robotic where it will fly without human pilots on it..

  44. Charles Buckman | June 23, 2012 at 11:19 am | Reply

    Two things here that always seem to guide what the top brass does: 1) never admit there was a mistake, 2) it costs too much to fix.

  45. Maybe it's just me, but if a principal member of the "Fighter Mafia" believes coating adhesives creates hypoxia for fighter pilots; do believe it is time for everyone to close their mouths, open their eyes and ears and listen.
    Pierre Sprey was the design brains of the A-10 Warthog.

  46. I am not a fighter pilot so please excuse my ignorance. You mean to tell me you can smell the fumes of the glue in the cockpit (still). I had another theory but this one is more likely . If this is true major irrisponsibility on the part of those in charge and really stupid considering the cost. ? would they not of caught this though during the grounding.

  47. Pierre Spray has hated anything Lockheed has done dating back to the F-104 years. His philosophy is "if Lockheed did it, it's not any good".

  48. Let me get this straight. You have F-22's that have two (2) jet engines and have already been produced and flying. Yes they have problems, so fix them. On the other hand you have F-35's that have one (1) jet engine and probably will utilize the same oxygen system as the F-22. Why bother with another aircraft that's going to have major issues ?!!! DOD contractors greasing politicians palms. What a waste !!!

  49. Rather than redesigning the glues and coatings why don't you got back to an oxygen system that uses tanks?

  50. so you have a system that generates concentrated O2 from compressor bleed air, and you have pilots passing out? why the heck are you worried about cockpit air quality? and how would anything but nanoscopic quantities of toxic glue gasses get into the system, can you image the VOLUME of air going into the intakes at 1.6M??? although My suspicions would point toward that awful engine lube oil smoke getting into the compressor, the most likely scenario is Still that they know Exactly what's wrong but it will take many millions per airframe to fix. and the LOX suggestions is looking better all the time

  51. Jim from A1716A | June 28, 2012 at 1:17 pm | Reply

    Two suggestions. 1. Strip the stealth coating from the airplane, load toxic sensors and duplicate the flight of those that crashed and run the test at high speeds/altitudes. 2. Put pilot in a In a cetrirfuge and measure lung function at 9g's for "x" seconds to see if that is sufficient to support consciousness for flight control during maneuvers.

  52. Not a real techie by trade. Question: could an air intake nozel (micro small hole) fitted to the front of the plane with a dedicated stand alone system to provide oxygen to the pilots work? Or could frozen oygen heated by the operating temperature of the plane generate enough oxygen for pilots operating at the altituted and performance level where they keep experiencing the problems be a viable solution?

  53. Occam's razor, sometimes what's right in front of you really is the answer. Most of us know what the majority of fighter pilots are like, right? Cocky doesn't begin to describe it (in most circumstances, met some chill as hell fighter jocks too). What fighter pilot on this planet is going to admit that his plane out-flew him? Of course there's still doubt, because no F-22 jock will admit that the air force's explanation has any truth to it. I'm not saying that the "glue" theory doesn't make complete sense and carry a lot of weight, I'm just saying maybe people are looking for zebras when they only hear horses.

  54. Set up a few test aircraft with the older liquid oxygen system and don't dilute it with cockpit air. Use bottled air for dilution. Wear a pressure suit not pressureized from the aircraft system. Pilot's breathing and skin will have no contact with any potential glue fumes.

  55. Holy crap…the "glue" does not make the jet stealthy. Sealant is used to bond RAM to the airframe. ITS NOT SOME SUPER SECRET! How the hell else would one keep something on a jet that travels at supersonic speeds? I highly doubt the fumes are causing hypoxia.

  56. Make robots to fly the plane and do not buy from China.

  57. Darrol Olsen knows. He filed a lawsuit because of mercury & other forbiden toxic materials in its stealth coating.
    Read how the government covered it up.

  58. If you've ever watched the deep-dive sequence in 'The Abyss', you have a better idea than Mr. Sprey does as to what the problem is. Only in reverse.

    Mankind, excluding Sherpas who have a unique gene, is specifically designed for optimum metabolic oxygen exchange within a band from sea level to maybe 8,000ft.

    Anything outside that band adds significant risk of the cells in your body burning sugar faster than oxygen can keep the reaction clean (sugar to starch, anoxic burn) which is why you have to be able to breathe pure oxygen anytime you go above 12,000ft.

    I know this because I look at people who come to Colorado expecting to ski like a native and find they are nearly blacked out from a single run down a diamond slope and just want to go back to the lodge where they have huge headaches (dehydration) and fatigue (low blood ox) for the rest of the day.

    Around about a fortnight in, your metabolism adjusts and you get used to our mild 'Mile Hi' hypoxic conditions but at 55-60,000ft, the pressure differential is so much that the way the oxygen permeates cell membranes changes and even breathing pure oxygen, you are not getting the saturation you need to keep the cells which are 'burning rich' (low altitude optimization) from pulling the biological equivalent of an overchoked engine.

    This is because the specific gravity is changing the air density and even if you have a high cockpit differential and are breathing pure oxygen, your body will have a hard time getting that oxygen on the corpuscle and from the corpuscle to a brain cell that is burning rich.

    High G at high altitude is pointless anyway because you are pushing Q limits on the airframe to generate enough speed to flat plate it's high-RCS side to dozens of sensors and denying _the missile_ it's ability to do it's optimum job in air which is (1-20K, halved. 20-40K halved again and 40K-60K thirded.) less than .5% as draggy as it is at sea level. As powerful as the APG-77 is, you shouldn't need to engage in a high G pull off because your missile has a pole about twice as long as the guy at 40,000ft and 4 times as long as the guy at 20,000ft.

    Why are they pulling so much G at height instead of flying like a U-2 pilot, letting the ALR-94 do it's job as an RF vacuum cleaner for the other fighters below/in front of them?

  59. Makes sense, at high speeds the skin heats up and the composite materials outgas, and the stuff is sucked up into the oxygen system by the engines and is sent to the pilots lungs.
    The “F-22 cough” is well known among pilots who fly it.

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