Fumes mixing with cabin-air in the APU?

[avbug]

Even if the APU were ingesting fluids or vapors, why would that have anything to do with anything in flight?

If CO is the issue, then recovery takes considerably longer than just a few minutes. Considering that monoxide attaches to hemoglobin at a rate 144 times that of oxygen, the recovery time to express it from the system is long. Further, if contamination of cabin air caused sickness, then there is nowhere in the cabin you can go to relieve yourself from this. More likely motion, or harmonics, etc.

Ingestion of fluids, oils, etc, in to the APU, or any other turbine, results in a rapid decrease in engine efficiency, rises in temperatures, etc, as the compressor cokes up (buildup on the compressor blades). This can result in volumetric output, and certainly if bleed air is being supplied by that compressor, some measure of contamination. However, this isn't rocket science, and that isn't a seal issue, either.

Further, due to air conditioning requirments, the bleed air supplies only part of the air input for pressure, conditioning, etc. The remainder is ambient, used to condition the supply-source air. This further dilutes the mixture entering the cabin, in most cases, considerably so. (In flight being a non-factor, as ram air is used to intercool the bleed air for conditioning purposes).

I still think it's a matter of racing stripes.

 

[tarp]

Saw the USA Today article too and wondered what others thought.

I'm split on this stuff. Deep down, I'm a get the job done kind of person. Pumped gas for two years when the stuff was 32 cents a gallon - never thought about fumes or skin contact. Worked construction for two summers and never wore a filter mask even through the worst moments of sawdust and drywall dust.

But now I'm sitting in a glass cockpit. I've never seen so much dust in an office environment as what this airplane spits out the vents - its like the thing "snows" dust. A guy farts in row 12 and 20 seconds later I smell it up front. We ingested a bird 3 months ago in #2 and the plane smelled like burnt bird dung for 2 hours. But worst of all, I've been through two winters where I have had the most severe bouts of the flu that I can remember in 45 years on the planet.

My airline company says there is nothing wrong with the airplanes, the APU's, the cleaning of the filters or the air recycling system. This is the same company that has sent me letters warning me for my excessive use of sick time even though I've only missed two weeks of work in two years due to the said cases of genuine flu complete with doctor's letters.

So am I working in a dirty, contaminated, unhealthy work environment or am I just a wimp? Do you think the company would put me in an unsafe environment and then not tell me? No..... I didn't think so either.

Like the coal miner (noted in the above post), I need my job. But like the coal miner, I might need protections from "black lung" or other on-the-job injury. The coal still has to come out of the earth and the planes still have to fly. The premise was that the coal miner understood on any given day the tunnel may collapse but he didn't anticipate the black dust would kill him. Same goes for me - I can still be put in a situation where I auger into the earth and I accept that risk, but I sure don't want to die because I caught some deadly disease from one of my customers or because they found out that Skydrol contains some human pesticide.

 

[avbug]

Bleed air isn't really filtered. It's for the most part clean air; especially at altitude. Certainly lab seals on bearings forward of the final compressor stages can contribute air contamination, and vapors entering the compressor will enter the bleed; there's little that can be done about that. Some recirc systems use HEPA filters and so forth to filter recirculated air, but this has no bearing on what's being brought into the cabin by the bleed air through the engines, APU, etc.

It's not uncommon for turbojet aircraft that ingest trees on impact in terrain to blow sawdust in the cabin. It happens.

In many cases, the outflow valves are forward in the cabin, as the engines are aft. Air is dumped via a delivery system throughout the cabin, but most often the air is vented from the cockpit or close to the cockpit, and in many cases the vented air is then used to cool or pressurize an avionics bay. In aircraft with such an arrangement, it's to be expected that any odors released farther aft will make their way forward, because that's the direction of airflow. This is also the case in virtually all light jets.

If a passenger is sick, certainly you can get sick it 's airborne. Most communicabe diseases aren't, but TB and others are...you can get it.

Don't worry about skydrol carrying a "human pesticide." It's toxic enough as it is. Breathing it in can make you very sick, just as contact with your skin is definitely to be avoided. Skydrol is nasty stuff. H5606 fluid is also quite toxic (and flammable), especially in a misted state. Breathing in a misted or vaporized quantity of 5606 can lead to limpoid pneumonia very quickly.

Then again, solar radiation at altitudes is a concern. EMF radiation in the aircraft is a hazard. Vapor from fuel is toxic. Most materials on board the aircraft, if burned, are toxic.

Even most food, including crew meals, is toxic. (irony).

Passengers are unstable and dangerous. I flew with a captain once who cut his eye opening a newspaper, for crying out loud. Flight attendants are social landmines for those who are married. Fingers close on doors. Raised edges in the jetway trip. Hari Krishnas in the lobby annoy and harrass. Children are crying, dogs barking, cats falling from the sky and becoming ingested in engine intakes and radar vents. I just can't take it any more! I can't take it! I'm going to McDonalds, where at least I can choke on something toxic that has some measure of public acceptance and FDA approval. Let me know when this whole lawsuit thing is over so I can come back to work.

What was the origional topic?