Toxic Cabin Air/Aerotoxic Syndrome

[JW411]

Now, you see, that's interesting for I flew the DC-10 for eight years also.

[mark exclamation]

Hi all
Just a couple of quick comments regarding this sad news and some of the issues people have raised.
I myself have been off flying duties after a fume event over 2 years ago but I think that was really the straw that broke the camels back as I have been feeling unwell for many years and indeed was lucky to survive kidney cancer some years ago.

Firstly, as has been said, we are all different genetically and our bodies can react differently to chemicals/toxins. I have seen evidence of chemical leaks, not in aviation, where a group of people have been exposed to the same chemical spill yet react differently, as diverse as from no effect to being confined to a wheelchair. It all depends on how our bodies process these toxins through our livers/kidneys and if they are efficiently disposed of from our bodies.
That is one of the problems facing this issue as for every single person affected by organophosphates, etc, then there are several hundred people from the same flight who are not, or at least not as badly.
I also believe that these problems are cumulative and these toxins build up in some of us over many years of low exposure until our bodies cannot cope anymore. That's what I believe has happened to me.

Secondly, the hot, high pressure air that can cause the oil or any other contaminant to disperse into the air conditioning.
Jet engines have 2 air conditioning supplies from the engine. One from the front bypass section, the low pressure (LP) air which is a lower temp compared to the one from deeper into the engine from the high pressure section (HP) which is at a much higher temp.
During most of a flight the engine is at high revs, T/O/climb/cruise, and the air supplies come from the LP air supply.
During descent or taxying the engine is mostly at idle and cannot maintain sufficient air supply from the LP alone so the HP air is then utilised and if there any contaminants in the ducting then they could be burnt off. Who's to say that this doesn't happen nearly all the time but that the amount involved doesn't cause a smell/fumes such that it doesn't get noticed?

That doesn't hide the fact that if an oil seal fails in either of these areas then oil fumes, which contain a small percent of organophosphate, will be released.

Well that's my small input but there is much more info from more qualified people on the net, specifically the Aerotoxic Association, Toxic Free Airlines and the Global Cabin Air Quality Executive [GCAQE], co-chaired by Tristan Loraine, an ex BA Captain who also suffers ill health.
It's a shame that more people at the coalface in aviation don't know about it and question why they sometimes feel so unhealthy/unfit!

Take care

[Turbine D]

Engine Bleed Air

Croqueteer,

I would like to know the real reason that Boeing have gone back to and independent supply of cabin air.

The B787 engines are "bleed-less" to improve the efficiency of the engines while reducing the weight, valving and piping complexities of both engine and aircraft, all of which reduces cost, the exception being those bleeds required for engine heating/cooling purposes. The traditional turbo-fan engines (two spool design) take air out of the compressor, usually in three locations. BOAC is correct, none of the removal location are in the turbine area.

For example, in the CF6 engines, bleed air is pulled off at the 7th, 8th and 11th stages of the high pressure compressor. This is pretty far back in the compressor and the air drawn off is warm. The 8th stage bleed air is what is provided exclusively to the aircraft for various purposes including cabin air.

So how might oil fumes get into the cabin air? Well, some air is drawn off the fan by-pass and is used for various reasons including pressurizing the "B" sump that sits in a compartment underneath the combustor forward of the HPT. The excess pressurization air is then sent forward and vents into the cavity area where the fan bearing and stub shaft joins the shaft connected to the LPT. The air is distributed through several compartments to eventually heat the shaft to maintain seal clearances.

Now as the seals begin to wear over engine operating time, some oil in the form of mist could possibly escape into the main stream airflow into the HP compressor and be drawn off at the 8th stage bleed into the cabin air. It would probably only happen in certain engine transient modes.

All engines are different in details so this is just one example and one possibility. It does seem to me that the chemical makeup of modern oils used in engines is important regarding air contamination and what crews (and passengers) are subjected to from time to time.

[Croqueteer]

Turbine, I am aware of the source of bleed air, but I suspect that independant compressors etc would incur a wt penalty. I can remember how substantial the compressors were on the Viscount, so my question stands.

[gas path]

The turbo compressors were not that big on the B707. Installed in the front of the pylons 2/3/4.
There is NO bleed taken from the 'hot' end. High pressure bleed will be taken from the back end and/or mid way along the compressor depending on the engine type. However this air can on occasion get contaminated with engine oil (overfilling in some cases or an oil seal problem).
The air conditioning Air Cycle Machines these days all have 'air bearings'.


@Sampan Angkasa
I would say that is an APU fault especially in the descent on the 777.
The APU can have a problem with oil seals when its got a few hours 'under its belt'. When the T/L's are retarded at TOD it causes a partial vacuum in the APU pneumatic duct and any oil residue will be drawn down into the pack heat exchangers. Hence it's noticeable in the descent!

[Dan Winterland]

The VC10s were wuite large and heavy. They could also introduce oil mist into the cabin if the lubricating oil had been overfilled during maintenace.

[SmsPro]

Sheep Dip?

Is this a joke? and the farm remark...? Trying to figure what is the hidden innuendo.

[Loose rivets]

I think that was already answered.




Just seen this. Sins of the fathers . . .


Jet fuel, plastics exposures cause disease in later generations; Reproductive diseases, obesity

[Mac the Knife]

With more than 600,000 certificated Commercial pilots in the U.S. alone, if this is a real phenomenon then very clear medical evidence for it MUST exist.

Mac

[BRE]

I believe in previous threads we had on the topic, it was said that there are alternative oils without organophosphates. What is the status (certified for all applications? service life?)

[BOAC]

Mac - welcome to the topic. Good to see a 'medic' here. I have not seen much out of the US, but a catalogue of 'events' (Europe and Aus only, I think) back to 1997 is here

Any professional medical interest welcome. There has been a poster on PPRune called 'aerotoxic' who is, I believe, involved with the site linked. He now shows as 'active' but there are no posts listed in search, so I guess the mods must have taken a dislike to his posts.

[Petercwelch]

Routine events

Attribution of illnesses to environmental factors requires real evidence, not just, I smelled something and then found I had renal cancer etc. i assume that flight departments have access to pilots medical histories but am not sure. Do they? Unscientifically based speculation can raise issues, but when these sorts of environmental concerns are investigated they usually turn out to be distributed randomly, and to have no basis on environment. Love Canal which was a cause célèbre for years in the US was never shown to have caused any disease. Cancer and vascular disease are the big killers in western countries and should be expected to occur everywhere.

[BOAC]

Peter - I think the thrust of the campaign is for exactly that - clarity. I believe blood tests can establish organo-phosphate exposure, but I do not think they are done on pilots who report 'fumes'. Should they be? 'Evidence' is at the moment largely circumstantial.

I understand that organo-phosphates are present in aero-engine synthetic oils and that O-Ps can cause cancer. I would like to see some sort of study to see if the two are linked in aviation.

[BRE]

I remember vaguely reading (here?) that Lufthansa has installed monitoring equipment on a handful of planes to actually obtain quatitative data.The question is how likely is it that a single plane actually has a fume event in a given year and would it be advisable to deploy monitoring equiment on a significant percentage of the fleet?

[Dengue_Dude]

I used to instruct on the 146/RJ for Avro and can confirm that the vast majority of their 'smelly' or fumes reports were attributable to the APU.

The fix apparently was to introduce a form of jet pump to lower the pressure in the APU gearbox to below atmospheric, thereby causing any leakage to go the 'other' way.

Either way, it just goes to underline how good the venerable VC10s were - no bleed powered ACMs in that aircraft - were they Rootes blowers?

We often had that kind of effect in the C130 when we have prop Gitz seal leaks - air from the compressor being taken for conditioning being contaminated. So I turned off the appropriate bleed valve.

Personally, I think we should 'bite the bullet' and insist on ambient air being compressed and conditioned. Yes I know it's heavier, more expensive - but I too believe this is the tip of an iceberg.

[Tinribs]

Sheep Dip Toxic

There was an earlier comment about sheep dip and its qualities.

There is no doubt that the orgaphosphates in some sheep dips cause serious health problems. Extensive protective clothing and systems are now required to use them after the problems being noted over a wide spectrum of users and long periods

I spent some years at an agricultural school and many years on the edge of farming, these problems are well known in farming and medical circles and there are posters about it market areas and agricultural suppliers.

The problem is that dipping sheep is both essential and legally required.
Undipped sheep suffer fly maggots which eat into the skin and cause extreme pain and even death. As a side issue such sheep rarely thrive so there is a profit motive.

Those dipping sheep, which are not enthusiastic about the process, suffer splashes or even soaking in the fluids used, and breath contaminated air. Dipping usualy takes place on good weather and so historically little heavy clothing was worn by operators and protective clothing unpopular

Th issue with sheep dip has lead to questions about the effects of similar organophosphates in aero engine oils and the fumes which may be found in the aircraft

[JW411]

I attended several sheep dipping sessions (as an interested observer) when I was a youngster and before the associated problems were known about. I don't suppose I was even wearing long trousers then!

It makes me shudder when I think about it.

[billysmart]

i see a few people making reference to the 146/rj.. they have different apu's ( mostly).

i have noticed that a LOT of crews either fail to use the overspeed to shut it down or just flick the off switch. the oil deprime valve is then closed causing oil biuld up in the system which eventually leaks out.

wonder how much is self inflicted

[JW411]

For the best part of 20 years we taught pilots to shut the APU down on the OVSPD. That is not to say that some of them did not do this at some point.

[Croqueteer]

Although the APU did smell, the serious problem I think is from misted oil from the compressor stages. Being brought up on a farm and thinking nothing of handling dipped sheep, maybe my problem predates the 146! There are so many articles on this subject, including a very good CD.