badflaps

On the CV-880 it was called "Perfumed Ester."

rickair7777

Yeah, Skydrol is the real bogeyman in my opinion. It's rare circumstances that it can get into the bleeds, but I have heard of shaft seal leaks on engine-driven HYD pumps. And it probably wouldn't take much of to hurt you.

Engine oil, not so much...if burnt Mobil 1 was a major health hazard the auto industry would have figured it out by now. Also it's much easier for oil to get into the bleed air...assuming you have a main bearing upstream of a bleed port. We probably all breathe some of that daily.

AKpilot

I seem to remember this happening on the 737-400 but not lately. I don't recall this issue on the NG. "the coalescer bag may be full of dirt and need changing (like a hoover bag!). When the bag is blocked the air bypasses the water separator."

I recall it as a nuisance only and not toxic.

Air Conditioning

rickair7777

The dirty sock smell is common to dirty (moldy?) pack bags.

Any smell that's more exotic or pungent would probably lead me to op check the O2 mask for a while.

UAL T38 Phlyer

Rick:

Mobil1 operates at typical car-engine temps. Jet Turbine Oil (Mobil II) has to operate at extremes of -65C, as well as the bearings in the hot-section of the engine. I'm not sure how hot the bearings get there, but probably much hotter than car bearings. It is why cars use plastic bearing seals, and jets use carbon disks......effective, but also fragile (the reason for many F-16 engine-failures).

One of the stabilizing additives they use in Mobil II (or equivalent) is Tricresyl Phosphate (TCP).

Tricresyl phosphate - Wikipedia, the free encyclopedia

I am convinced that oil-seal leaks upstream of the compressor in the F-22 are causing TCP poisoning of the pilot, as bleed air is used in the OBOGS system.

TCP is a known nerve-agent.

I'm a mechanical engineer, not chemical, but I think synthetic car oils are made using the fundamental components of synthetic aviation oils...minus the (toxic) stabilizing additives. Which means Mobil 1 isn't really much different coming out of the exhaust pipe than regular oil.

I ran Mobil II in a truck in college (before I knew about TCP). It ran great, even got better mileage....but the exhaust did smell different.

Anyway, I usually first suspect a dirty water-separator sock when an air conditioner stinketh.

Airhoss

Guys really? Anybody who's flown a 737-300 or 500 should be aware of the dirty sock smell that comes from the pack filters being damp and getting mildewy.

It is a seriously common and I thought well known deal on the older 737's.