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... pilots, who flew combat missions in the Iraq War, said they love flying the $400 million jets. But a faulty oxygen system that is suffocating the pilots and causing blackouts is making them fear for their lives and for the lives of people on the ground. Many other F-22 pilots have experienced disorientation, difficulty breathing and forgetfulness in the stealth fighters as well as a cough that follows them even after they land.
http://www.huffingtonpost.com/2012/05/0 ... 94880.html" onclick="window.open(this.href);return false;

http://abcnews.go.com/Blotter/fighter-p ... d=16294011" onclick="window.open(this.href);return false;

As someone who was specifically trained to work on aircraft oxygen systems (and did so for more than a decade), I'll say this about that. The USAF went with a system for the F-22 that generates (or sieves) oxygen from the atmosphere. They did this in an attempt to reduce the necessity of servicing the aircraft with liquid oxygen, and the inherent maintenance costs involved with those systems. However, when liquid oxygen systems are well-maintained (which they are 99.99% of the time on USAF aircraft), they SIMPLY WORK. Its a tried and true concept. If they can't iron the bugs out of the current system in short order, they really need to look at retrofitting the aircraft with a traditional LOX system.

Thanks for the explaination, HP!
I was wondering why it was such a problem. I mean c'mon, how long have they been putting oxygen masks in fighter A/C?

The Marshal wrote: . . . how long have they been putting oxygen masks in fighter A/C?

They had them in WW2. I'm not sure about before that.

The Marshal wrote:Thanks for the explaination, HP!
I was wondering why it was such a problem. I mean c'mon, how long have they been putting oxygen masks in fighter A/C?

I thought that the problem might be the source of the oxygen, not that there were no masks. Where does it say there are no masks???

G26ster wrote:

The Marshal wrote:Thanks for the explaination, HP!
I was wondering why it was such a problem. I mean c'mon, how long have they been putting oxygen masks in fighter A/C?

I thought that the problem might be the source of the oxygen, not that there were no masks. Where does it say there are no masks???

It doesn't say there were not masks.
But there is a system that has worked well for generations. Now they risk pilots' lives with a new system?
How about making sure it works before replacing that old system which we already know works?

mgood wrote:

G26ster wrote:

The Marshal wrote:Thanks for the explaination, HP!
I was wondering why it was such a problem. I mean c'mon, how long have they been putting oxygen masks in fighter A/C?

I thought that the problem might be the source of the oxygen, not that there were no masks. Where does it say there are no masks???

It doesn't say there were not masks.
But there is a system that has worked well for generations. Now they risk pilots' lives with a new system?
How about making sure it works before replacing that old system which we already know works?

I think the jist of the articles is the pressure being put on the whistle blowers:

"Despite the known safety issues, F-22 pilots have been ordered to continue flying. In fact, the Air Force is now threatening pilots with disciplinary action if they refuse to fly for safety reasons. "

I've flown numerous military aircraft with "new" systems. Some developed problems after years, some were flawed from the get go, and many others worked well. There is always risk involved with new systems, as testing can not duplicate the thousands of hours flown before faults are found and addressed. I think it's sad that pressure is being applied to the pilots. I don't know what the thinking was in replacing the old oxygen system with a new one, but there must have been a reason. The fact that it's "new" shouldn't automatically preclude it's use in the design. Hopefully there will be more investigation of this issue.

G26ster wrote:

mgood wrote:

G26ster wrote:

The Marshal wrote:Thanks for the explaination, HP!
I was wondering why it was such a problem. I mean c'mon, how long have they been putting oxygen masks in fighter A/C?

I thought that the problem might be the source of the oxygen, not that there were no masks. Where does it say there are no masks???

It doesn't say there were not masks.
But there is a system that has worked well for generations. Now they risk pilots' lives with a new system?
How about making sure it works before replacing that old system which we already know works?

I think the jist of the articles is the pressure being put on the whistle blowers:

"Despite the known safety issues, F-22 pilots have been ordered to continue flying. In fact, the Air Force is now threatening pilots with disciplinary action if they refuse to fly for safety reasons. "

I've flown numerous military aircraft with "new" systems. Some developed problems after years, some were flawed from the get go, and many others worked well. There is always risk involved with new systems, as testing can not duplicate the thousands of hours flown before faults are found and addressed. I think it's sad that pressure is being applied to the pilots. I don't know what the thinking was in replacing the old oxygen system with a new one, but there must have been a reason. The fact that it's "new" shouldn't automatically preclude it's use in the design. Hopefully there will be more investigation of this issue.

Some of the factors involved were money (of course) and turn time, that is the time it takes to get the jet ready to go again. In a civilian aircraft, oxygen is for emergency use, but for military aircraft in combat especially, the pilot(s) or crew are on it for long periods. Originally aircraft had gaseous oxygen cylinders under low pressure, but they were bulky and didn't last long. They later went to high-pressure gaseous cylinders, but they had a lot of weight and still didn't extend the useful time by that much. Later, they found a way (through the use of a dewar, like a thermos sort of) that they could keep liquid oxygen in a container on an aircraft, allow it to boil to a gas and then warm it for breathing...a LOT could be carried in a small container, too. But, there is a price to be paid. The systems leak, because they are so cold they can be "cantankerous" in operation if not cared for properly, and of course, it can be a hazard. But, with well-trained maintainers and a good logistics system, its a tried and true method of oxygen delivery on military aircraft (civilian planes still use cylinders of various types). However, the USAF decided they wanted to put in a system that could make its own oxygen from the atmosphere, as I said above. To save weight, to save money (in personnel and support equipment), and to save time not servicing the oxygen. All nice in theory, but the engineers often over-reach because things to them work on paper (or the electronic version) but don't always hold up in the real world. Its for this reason that the FAA still requires the use of magnetos on small aircraft when cars have had electronic ignition systems for many years...because magnetos work in the envelope of flight. When some company finally convinces the FAA they have 99% of the bugs worked out of electronic ignition, the FAA will authorize it...just like the way it should have been with this oxygen system business.

Now that I think about it, how do you sieve oxygen out of the air at an altitude where there is little oxygen and you need an oxygen mask/system to breathe? It must be pretty efficient system to do that.

When some company finally convinces the FAA they have 99% of the bugs worked out of electronic ignition, the FAA will authorize it...just like the way it should have been with this oxygen system business.

Does the FAA have oversight of military aircraft?

WildBill wrote:Now that I think about it, how do you sieve oxygen out of the air at an altitude where there is little oxygen and you need an oxygen mask/system to breathe? It must be pretty efficient system to do that.

When some company finally convinces the FAA they have 99% of the bugs worked out of electronic ignition, the FAA will authorize it...just like the way it should have been with this oxygen system business.

Does the FAA have oversight of military aircraft?

As to the first question, though I was taught OF such a system, I was never taught ABOUT the system, nor did I work on one. Supposedly it uses something like a catalytic converter, though. And as to the second part, No. Which is why the military can get away with all the "stuff" they do, like this super-cool (and super-buggy) new oxygen system...

I believe that this is the technology used to supply the oxygen for the F-22. http://en.wikipedia.org/wiki/Oxygen_concentrator" onclick="window.open(this.href);return false;

Heartland Patriot wrote:

WildBill wrote:Now that I think about it, how do you sieve oxygen out of the air at an altitude where there is little oxygen and you need an oxygen mask/system to breathe? It must be pretty efficient system to do that.

When some company finally convinces the FAA they have 99% of the bugs worked out of electronic ignition, the FAA will authorize it...just like the way it should have been with this oxygen system business.

Does the FAA have oversight of military aircraft?

As to the first question, though I was taught OF such a system, I was never taught ABOUT the system, nor did I work on one. Supposedly it uses something like a catalytic converter, though. And as to the second part, No. Which is why the military can get away with all the "stuff" they do, like this super-cool (and super-buggy) new oxygen system...

I would think it was a ram air system and scrubber, possibly soda lime or potassium hydroxide.

Dragonfighter wrote:

Heartland Patriot wrote:

WildBill wrote:Now that I think about it, how do you sieve oxygen out of the air at an altitude where there is little oxygen and you need an oxygen mask/system to breathe? It must be pretty efficient system to do that.

When some company finally convinces the FAA they have 99% of the bugs worked out of electronic ignition, the FAA will authorize it...just like the way it should have been with this oxygen system business.

Does the FAA have oversight of military aircraft?

As to the first question, though I was taught OF such a system, I was never taught ABOUT the system, nor did I work on one. Supposedly it uses something like a catalytic converter, though. And as to the second part, No. Which is why the military can get away with all the "stuff" they do, like this super-cool (and super-buggy) new oxygen system...

I would think it was a ram air system and scrubber, possibly soda lime or potassium hydroxide.

Soda lime and potassium hydroxide will only scrub out the CO2. I wouldn't think that they would want to or need to recycle the air.

I believe the YF-22 uses an MSOC (Molecular Sieve Oxygen Concentrator) http://libraryonline.erau.edu/online-fu ... M92-22.pdf" onclick="window.open(this.href);return false;

EDIT TO ADD: There is some pretty good info on the MSOC and assocaited problems with high altitude and high speed flight here http://aeroden.files.wordpress.com/2011 ... _pep__.pdf" onclick="window.open(this.href);return false; (Large file, over 10MB)

More info: http://www.f20a.com/f20obogs.htm" onclick="window.open(this.href);return false;

Keith B wrote:I believe the YF-22 uses an MSOC (Molecular Sieve Oxygen Concentrator) http://libraryonline.erau.edu/online-fu ... M92-22.pdf" onclick="window.open(this.href);return false;

EDIT TO ADD: There is some pretty good info on the MSOC and assocaited problems with high altitude and high speed flight here http://aeroden.files.wordpress.com/2011 ... _pep__.pdf" onclick="window.open(this.href);return false; (Large file, over 10MB)

More info: http://www.f20a.com/f20obogs.htm" onclick="window.open(this.href);return false;

Interesting reading. Thanks Keith.