F-22 Problems

[Bob Parks]

I watched 60 Minutes tonight while they discussed the breathing oxygen problems with that airplane and the pilots who have suffered from it. There were two pilots who stood down from flying it and in my opinion have slit their career throats . I applaud them for having the guts to face down the brass to illuminate this problem that has already killed one pilot and endangered several others including the men who were interviewed on the program. I was appalled to learn that breathing oxygen was bled off the engines before being compressed, fed through a filter, and then into the mask. Fifty five years ago when we were working on the 707 the FAA dictated that air for the passenger cabin would originate from a source OUTSIDE of the engines, hence the turbo compressors mounted on top of the engines that took clean air from the atmosphere. The military brass claims that they don't know what the problem is because the air is passed through a filter. Black mucous in the nasal cavities of the pilots indicated that carbon from the filters was being ingested and THAT couldn't be a problem. Is this supposed to be progress? Air that is bled from the compressor section of a gas turbine is not clean and the military engines are running a lot different than civilian engines. I wonder if they will catch on.

[future328driver]

In my prior career I designed ECS and pressurization systems for the Citation Bravo, Ultra and Excel. On the Citation series, the cabin air is taken from the bypass section of the engine and then "processed" through heat exchangers,air cycle machines and mass flow control valves to condition it for the cabin.

[Bob Parks]

Originally Posted by future328driver

In my prior career I designed ECS and pressurization systems for the Citation Bravo, Ultra and Excel. On the Citation series, the cabin air is taken from the bypass section of the engine and then "processed" through heat exchangers,air cycle machines and mass flow control valves to condition it for the cabin.

I, too, have done considerable ECS work on the 767 and 777 and I know that the cabin air was bleed air and that it was thoroughly processed through a series of condensers,etc. I think there must be a difference in the way the military engines are run and that the beed air is not being properly filtered. What else could it be?

[1_can_dream]

Isn't the system that generates oxygen in these airplanes something that hasn't been done before in any other aircraft? I remember reading somewhere that it was designed to generate oxygen for the life of the aircraft and therefore making oxygen tanks a thing of the past. Wouldn't oxygen tanks seem like an appropriate fix to the problem?

[SpecialK43]

Originally Posted by Bob Parks

There were two pilots who stood down from flying it and in my opinion have slit their career throats . I applaud them for having the guts to face down the brass to illuminate this problem that has already killed one pilot and endangered several others including the men who were interviewed on the program. .

My aviation buddy also said that they were committing career suicide. I replied, To them, getting back into one of those planes would be committing actual suicide. The pilot who was killed was one of the best to come out of WMU aviation program. I didn't attend the memorial service they had for him last year here, but I was out on lake michigan when the I noticed four fighter jets coming in to do a flyover. They were F-15s.

[Bob Parks]

Originally Posted by 1_can_dream

Isn't the system that generates oxygen in these airplanes something that hasn't been done before in any other aircraft? I remember reading somewhere that it was designed to generate oxygen for the life of the aircraft and therefore making oxygen tanks a thing of the past. Wouldn't oxygen tanks seem like an appropriate fix to the problem?

There are tanks and oxygen generators but they take up space and add weight... but they wouldn't kill the pilot. High pressure oxygen tanks are dangerous and wouldn't be too nice to be hit in a dogfight. Space is at a premium in these airplanes and I imagine weight is critical too so it makes sense to use engine intake air but I think it has to be scrubbed and filtered better.

[RWatters]

It's amazing that this same exact story has been going for so long as there's still no resolution for it. It's also amazing how quickly the government and Lockheed are to say the plane has no problems. What else does it take when someone has already died because of it?

It's a really crappy situation because I just watched the plane do a demo Saturday and it's absolutely amazing what that thing is capable of. It's such an awesome plane to watch, yet at the same time you know what dark side it is hiding and it really makes you think twice about it.

Included a snapshot I took of it peforming in St. Joe MO on Saturday.

[1_can_dream]

Originally Posted by Bob Parks

There are tanks and oxygen generators but they take up space and add weight... but they wouldn't kill the pilot. High pressure oxygen tanks are dangerous and wouldn't be too nice to be hit in a dogfight. Space is at a premium in these airplanes and I imagine weight is critical too so it makes sense to use engine intake air but I think it has to be scrubbed and filtered better.

I figured space would be the biggest limiting factor since things are pretty tightly packed and a redesign isn't cheap or even feasible. I'm just a little surprised that after this long they haven't identified and fixed the root cause of the problem. You would think LMC would have enough competent engineers to at the very least identify what's causing the problems and be on their way to fixing it at this point.

[Auraraptor]

http://www.cbsnews.com/video/watch/?...in;cbsCarousel

[James_Woods]

I just saw the 60 minutes lady reporter state on public TV this morning that possibly "this might just be a human issue (i.e. - not the plane systems) because (get this) 'perhaps man is just not able physically to fly this fast and this high'".

Yes, really. I could not believe my own ears.

[Tspringer]

The F22 could solve this issue and it's nearing obsolescence in one swoop... Remove the pilot and convert them to remote pilots.

The maneuvering limits of the airframe far exceed those of the pilot. The pilot is the limiting factor in almost all areas.


Terry

[1_can_dream]

The most recent article on CNN says that there are now maintenance personnel that have experienced the same hypoxia symptoms while being in the cockpit on the ground. They weren't on the mask, simply in the cockpit for engine run ups.

[RWatters]

Originally Posted by 1_can_dream

The most recent article on CNN says that there are now maintenance personnel that have experienced the same hypoxia symptoms while being in the cockpit on the ground. They weren't on the mask, simply in the cockpit for engine run ups.

Just read that as well. W.T.F.

[James_Woods]

Originally Posted by RWatters

Just read that as well. W.T.F.

The only thing that could come to mind to cause breathing issues at ground level (without the oxygen system) is if engine exhaust or other fumes are getting into the cockpit.

I also heard that they had put a modification of a carbon filter into the oxygen system, but then decided that it was causing more harm than good - and have now taken this out.

I have a question: Is this really an oxygen system (as in oxygen from a bottle), or is it just a compressed air system? It seems to me to be unlikely that they could make a system to actually separate oxygen from the air small enough to carry on board a fighter jet.

[1_can_dream]

From what I've read the carbon filter was for the mask and not for the cabin. I believe the "oxygen system" in the plane isn't from a bottle, they are generating it from air coming into the turbines. Someone correct me if I'm wrong please!

[James_Woods]

Originally Posted by 1_can_dream

From what I've read the carbon filter was for the mask and not for the cabin. I believe the "oxygen system" in the plane isn't from a bottle, they are generating it from air coming into the turbines. Someone correct me if I'm wrong please!

That is what I am assuming as well - but I cannot see how they could actually separate out pure oxygen from the air stream in a system small and light enough to go in a fighter. Isn't commercial oxygen made by liquification of air, and then stratified separation? That sounds big and heavy to me - which made me wonder if this is not just a compression system like a face-mask sized pressurized cabin system.

[Bob Parks]

Originally Posted by 1_can_dream

From what I've read the carbon filter was for the mask and not for the cabin. I believe the "oxygen system" in the plane isn't from a bottle, they are generating it from air coming into the turbines. Someone correct me if I'm wrong please!

From what I have read and seen, the oxygen is taken out of the engine intakes (compressor air) , run through some kind of condenser/filter/purifier and then into the cockpit system. The compressor air can be full of all kinds of contaminates including oil mist from the shaft labyrinth seals. By the 14th or 15th stage it is around 450 degrees so from there on it needs a lot of processing. I'm basing this from what I know about the engines on the big tin birds and helping to design the ECS on them so if I'm off base , let me have it.

[James_Woods]

Originally Posted by Bob Parks

From what I have read and seen, the oxygen is taken out of the engine intakes (compressor air) , run through some kind of condenser/filter/purifier and then into the cockpit system. The compressor air can be full of all kinds of contaminates including oil mist from the shaft labyrinth seals. By the 14th or 15th stage it is around 450 degrees so from there on it needs a lot of processing. I'm basing this from what I know about the engines on the big tin birds and helping to design the ECS on them so if I'm off base , let me have it.

That sounds right to me, but what I cannot figure out is how they separate pure oxygen out of just compressed atmospheric air.

[Gatorrari]

The system is known as OBOGS (OnBoard Oxygen Generating System) and has been used on jet fighters for years; I know for a fact that the F-14 had it. Why the F-22's OBOGS is not working properly is a mystery.

[1_can_dream]

Originally Posted by Gatorrari

The system is known as OBOGS (OnBoard Oxygen Generating System) and has been used on jet fighters for years; I know for a fact that the F-14 had it. Why the F-22's OBOGS is not working properly is a mystery.

Are you sure that's correct? I thought the system on the F-22 was something that hadn't been used on a fighter before.