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Print 19 comment(s) - last by im4aqt.. on Aug 2 at 3:00 PM

Faulty valve could contribute to hypoxia-like symptoms experienced by some pilots

The United States Air Force's premier air superiority fighter is the F-22 Raptor. However, the F-22 has had problems over the last few years with pilots at times experiencing hypoxia-like symptoms during flight. The F-22 fleet was grounded while an investigation into the problem was conducted.
 
Ultimately, USAF found no hard evidence on what was causing the symptoms in some pilots and the aircraft were returned to the skies with no fixes applied. 
 
The Air Force has now announced that after further review, it has discovered a faulty valve on the pressurized vests F-22 pilots wear during flights. The valve will be replaced by the end of the year and pilots are currently not wearing the pressurized vests during flights. The move to replace the valve and ban the vests from being worn currently is an attempt to help address some pilot complaints of nausea and dizziness while operating the fighter.
 
The valve in question connects the plane's onboard oxygen generation system to the vest and inflates the vest to protect pilots during high G maneuvers. However, the valve has a flaw because the vests to be constantly inflated even when the aircraft is operating at lower altitudes where the vest wasn't required.

 
"It [the vest] restricts his breathing, it restricts his ability to do normal inhalation and exhalation. ... The pressurization schedule in the F-22 inflates prematurely, so we removed this,” Maj. Gen. Charles Lyon said at a Pentagon briefing Tuesday. Lyon is the director of operations for Air Combat Command. Air Force officials believe that the pressure on the chest of the pilot due to the faulty valve could cause the symptoms of hypoxia that some pilots are experiencing.
 
Defense News reports that within the next month the USAF will start testing a new valve that will provide more tension and restrict airflow into the pressure vests until the airflow is needed.
 
Lyon also went on to say that there was no evidence that the faulty valve contributed to the fatal F-22 crash resulting in the death of pilot Capt. Jeff "Bong" Haney.

Source: Defense News



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By MrBlastman on 8/1/2012 11:02:52 AM , Rating: 1
Nah I think there are ways around it but our physicists are playing catch-up to get there. The higgs field is totally untapped. :)

UAVs will be a stop-gap. They'll fill a role for a while but ultimately the MK1 will be back in the saddle in whatever we're flying by then (I'm not sure it'd even be called flying at that point).


By Bad-Karma on 8/1/2012 11:58:46 AM , Rating: 2
quote:
Nah I think there are ways around it but our physicists are playing catch-up to get there. The higgs field is totally untapped. :)


Thw abilty for a pilot to with stand G forces is base on the G-load, G aspect and F load time, as well as health and training factors.

Just about every fighter we have produced since the F-15 in the early 70s has had a G limiter built into the flight controls. The planes are built to withstand far more but the limiting factor has been and will continue to be the pilot. Even with the most advanced G-suits, around 9 Gs have been about the limit of human endurance for quite some time now. Proper physical conditioning and health can get a pilot a few more tenths of a G but that's about it.

The other issue that is creeping up is that during prolonged bouts of high Gs and multi-axis-manuvering pilots are experiencing losses in spacial orientation, situational awareness and some are even experiencing prolonged periods of vertigo. These modern hi-performance aircraft are literally capable of killing their pilot with their performance. So keeping the pilot on the ground is becoming an ever enticing field of pursuit. The F-22 may well be one of the last dedicated manned fighters we produce.


By MrBlastman on 8/1/2012 12:27:01 PM , Rating: 1
Everything you said is true.

quote:
The F-22 may well be one of the last dedicated manned fighters we produce.


This may also be true for a while. Not forever though. You've got to think farther ahead to get past our physical limitations.

I firmly believe that we'll break through the barriers of them and not through making humans "stronger." I also don't think we'll make aircraft "gentler" either, to do it. Nothing in our universe is as it seems and once people accept the notion that we are a product of our own reality, they can begin to challenge paradigms and grasp the untouchable. The mentality of "what you see--is" will be knocked down farther than it ever has been.

Yeah, it sounds like science fiction mumbo-jumbo because it is and that's where we're headed, it'll just take a while to get there. G-forces are only deadly as long as we are stuck within the confines of our own universal laws and constants.

Hence, the need for more scientific funding. :)

In the meantime, I'm prepared to pay homage to our robot guardians for the time being. Nothing will ever replace the MK1 eyeball though, completely.


By 91TTZ on 8/1/2012 4:38:52 PM , Rating: 2
quote:
I firmly believe that we'll break through the barriers of them and not through making humans "stronger." I also don't think we'll make aircraft "gentler" either, to do it. Nothing in our universe is as it seems and once people accept the notion that we are a product of our own reality, they can begin to challenge paradigms and grasp the untouchable. The mentality of "what you see--is" will be knocked down farther than it ever has been. Yeah, it sounds like science fiction mumbo-jumbo because it is and that's where we're headed, it'll just take a while to get there. G-forces are only deadly as long as we are stuck within the confines of our own universal laws and constants.


Good luck trying to "will" yourself around fundamental laws of physics.


By MrBlastman on 8/2/2012 11:08:07 AM , Rating: 2
The fundamental laws of physics only apply to our universe--and as such, we can't violate them here.

Re-read what I said as it is very deep. I never suggested violating our own laws. I could just blurt it out but that isn't as fun. :)

There's always a way around something in theory, you just have to be highly creative and not be stuck on the same paradigms everyone else is--while of course obeying the local laws.


By geddarkstorm on 8/1/2012 12:55:40 PM , Rating: 3
By "forces the human body can withstand" do you mean G-forces? We've had plane designs that could go way past the human limit there for a long time.


RE: Maybe we've reached the limits of the human body?
By Noya on 8/1/2012 9:01:51 PM , Rating: 2
quote:
In Iraq we were shooting down Mig 29's, THE most advanced fighter in the world not made in the US , beyond visual range!


Now that is funny.


By Warren21 on 8/2/2012 9:35:02 AM , Rating: 2
I thought so too. Flankers and Typhoons be damned.


Wut
By Lifted on 8/1/2012 10:34:04 AM , Rating: 5
I would swear I've read articles in the past stating other pilots had experienced hypoxia-like symptoms... a lot of other pilots. Is the Air Force seriously telling us that none of their pilots realized their vest were suffocating them?

The Air Force was either lying then or they're lying now... or F-22 pilots are retarded, which I highly doubt is the case here.




RE: Wut
By Ringold on 8/1/2012 11:14:55 AM , Rating: 2
I'm not one to criticize the military often, but I think the Air Force has been... less than honest... about this from the very start. I trust the reports of the multi-thousand-hour sky-god pilots over the military-industrial bureaucracy any day. They're just trying to cover their own ass.


RE: Wut
By MrBlastman on 8/1/2012 12:34:11 PM , Rating: 2
There is definitely more to this story than vests causing the hypoxia. You have to remember though--high level military decisions revolve heavily around politics. If they admit something else is the cause of the problem, one general and one congressman/senator might cost themselves thousands or millions in kickbacks plus earmarks geared towards their constituents and contributors.

It's stupid but that is how the game is played. Remember, the screwdriver doesn't really cost 10,000 bucks. The screwdriver is just listed as costing this much to cover up other stuff they don't want to report.

This "oh the suit valve caused it," is all part of that game. Someone out there has a lot to lose if the real truth comes out. We can only hope that someday a pilot might speak up about it. They probably won't, though, as there is far too much at stake. It'll probably take a few more people dying for some pilots to change their minds.


RE: Wut
By geddarkstorm on 8/1/2012 12:59:35 PM , Rating: 2
Yeah seriously. If it was the vests, why doesn't this problem affect all our pilots who wear these vests (which have been around for a long time), and not just the F-22s?

I wonder if we accidentally subcontracted substandard parts for the OOG (or F-22 specific vest interfaces?) from China or something; like all those defective Chinese electronics that were showing up in our military equipment.


Create a pressurized cabin.
By im4aqt on 8/1/2012 5:02:53 PM , Rating: 1
The problem could effectively reduced to zero by simply installing a pressurized cabin for the pilot. That way toxins would no longer be forced into the bloodstream in high G situations.




RE: Create a pressurized cabin.
By inperfectdarkness on 8/2/2012 7:34:41 AM , Rating: 2
you don't seem to understand the fundamental principles of how a fighter jet affects its pilot.

the cabins are already pressurized--usually to ~20-30k feet. the oxygen supply the pilot breathes is pressurized to ~5-8k feet or so.

in a high-g maneuver, the danger to the pilot isn't from "toxins" in the blood, it's from g-loc (gravity-induced loss of consciousness). blood pools in the lower extremities during a high-g turn, which causes the blackout. the solution is to keep blood in the head/arms.

pressure suits are designed to assist this by squeezing the lower extremities to "push" blood further up into the body. pressurizing the entire cabin will do nothing to counter this, as the pilot's entire body would still be under one constant ambient pressure.

you need to do your homework.


RE: Create a pressurized cabin.
By im4aqt on 8/2/2012 3:00:55 PM , Rating: 2
I'm sorry for the misunderstanding. My assertion is that the materials used in construction of the oxygen breathing system decompose at a molecular level during high G situations. This causes the pilot to be breathing not only oxygen but a soup of gases that are scrubbed from the breathing system. By pressurizing the cabin to a point where no breathing system is required will alleviate the situation.


Insider Info
By cali_guy76 on 8/1/2012 12:13:02 PM , Rating: 2
I have a friend that is on the team overseeing the whole investigation and they have deamed that the vest is not the smoking gun, in fact, they still have reports of hypoxia related symptons after the vests were removed.

This is nothing but a diflection tactic to buy the AF more time to investigate and give current Raptor pilots a warm fuzzy.




RE: Insider Info
By jeffkro on 8/2/2012 1:53:58 AM , Rating: 2
Pretty sure your friend wouldnt be allowed to talk about it


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