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Toxic Cabin Air/Aerotoxic Syndrome

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Toxic Cabin Air/Aerotoxic Syndrome

Old 6th Feb 2013, 17:28
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In the pocket

You say "allegedly in the pocket of the airline". I must correct you (with humble apologies): They are evidently in the pockets of the airlines and manufacturers - it is where all the money comes from to pay for the swish restaurant that we mere pilots are no longer allowed to use because we commented on how brilliant and cheap it was...

The XAA is now an "agency" or "trust" if you care to misuse that word. It operates at nil cost to government, and gets a free hand as a quid pro quo. The unintended consequence of this is that the XAA cannot rock the boat as it would be killing the goose that is laying their golden egg. All very cosy...
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Old 7th Feb 2013, 14:03
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Contaminated Engine Bleed Air Explained

For those of you who are unfamiliar with the term 'bleed air' and how it gets contaminated. The following basic videos might help explain it more:

Contaminated Engine Bleed Air Explained - Vimeo

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Old 7th Feb 2013, 14:45
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Somebody mentioned previously that they would get a sweaty socks smell at around 8,000 feet in the descent.

In my previous company that was about where we used to start the APU prior to landing (perhaps a little bit lower).
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Old 7th Feb 2013, 21:12
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Smell In Descent

I have never operated an aircraft where we start the APU in descent - in fact we wait until we're about to turn onto stand...

However, the conclusion I've arrived at for the regular occurence of this smell in descent is as follows:

No.1 (and poss No.2 depending on type) bearings are the most likely culprit as they are upstream in the gas-flow from the air bleeds.

These bearings are normally protected from oil loss by two or more seals, essentially a carbon seal and a labyrinth air seal. The labyrinth seal is a number of sharp-edged discs on the rotor, surrounded by an abradable case. When the seal is installed and the engine starts the discs cut minute grooves in the abradable case lining. The result is a labyrinthine route to the gas flow from the space between the carbon seal and the labyrinth seal - hence the name. The purpose of this seal is simply to provide enough restriction to air flow that when a dedicated bleed air source is fed through holes in the rotor shaft into the space between the two seals there is enough back-pressure for the pressure to exceed oil system (scavenge system) pressure. Because of this air leaks inwards through the carbon seal instead of oil leaking out. This is the reason why air needs to be extracted from scavenged oil.

When the labyrinth seal wears over time the back pressure is reduced. This is not normally a problem because there is a large air supply pressure. However, in descent the bleed air pressure is low because the engine is at idle. Again this is not a probem because the fan is generally acting as an airbrake, meaning that a microscopic end-float movement of the rotorshaft rearwards occurs. This has the effect of moving the discs of the labyrinth seal out of alignment with their grooves, thereby reducing the gap and improving back pressure. However, when the aircraft goes below FL100, or (and THIS is the smell in the middle east folks) a higher speed limit point, and speed reduces, so the AIS-based load on the fan reduces, allowing end-float to reduce, and the labyrinth seal discs to move back towards alignment with their grooves. The back pressure consequently collapses, and we get oil leaking past the seal and into the gas flow.

Next time you smell "the oil rigs" in the gulf think again: those flare-offs should not smell of oil, but of smoke, shouldn't they? What you are smelling is simply oil - from your own engines. If you're one of the 3% you should be worried at that point...

Last edited by Chunky Monkey; 8th Feb 2013 at 09:05.
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Old 7th Feb 2013, 22:41
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MS17

All correct Chunky monkey.

The next bit you need to understand is that anybody breathing the oil fumes is being exposed to organophosphates (work related).

Here is MS 17 a UK HSE (Health & Safety Executive) document from 2000, which graphically explains the medical effects on any exposed human beings.

Sadly this document is no longer avaialble from the Government sources - I wonder why?

http://www.aerotoxic.org/download/do...dence/MS17.pdf

If only MS 17 were to be reissued to doctors, they might begin to understand the mysterious illnesses they witness every day, but can't work out what is causing the range of symptoms....
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Old 8th Feb 2013, 16:08
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Not sure if this link has been placed before, but it is apparent that the medical authorities in the UK place very little store by this possible risk whereas as you will see from the Australian efforts, they have put significant effort into it.

Australian Senate air travel report

I think it a worthwhile idea to ensure that GPs are at least aware of the questions.

This written evidence from the House of Lords' Select Committee on Science and Technology is of interest and contains a lot of references for those interested.

Last edited by BOAC; 8th Feb 2013 at 16:12.
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Old 9th Feb 2013, 10:17
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OP report - 2004

BOAC,

GP's knew about this issue in 2000, as made clear in this 2004 report.

http://www.aerotoxic.org/download/do...e/OPReport.pdf Page 15.

They just 'forgot' to tell one another about it.

Just think how much money would be saved if people were properly diagnosed - let alone making them better by appropriate treatments.

Anti-depressants are hardly likely to cure somebody who has been poisoned.

Last edited by Dream Buster; 9th Feb 2013 at 10:18.
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Old 9th Feb 2013, 12:25
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I flew the Embraer 145 with Richard and did my command training with him.
The stale sock smell was an odour we got used to on older airframes associated with low thrust and often an icing encounter. The general view was that it manifested itself with the opening of the high stage bleed valve.

Although we complained regularly about this...nothing effective was ever done. Self evidently if, as we suspected, it was a leaking bearing seal then the remedy would have involved major engine surgery.

That was then.......

I now fly the business jet version of this aircraft, the Legacy.

I reported this smell a few weeks ago. The aircraft was immediately grounded and Rolls Royce replaced the engine............no ifs or buts.

Its would appear that belatedly the industry is taking notice (despite continued denials) and one can only wonder at the conversations that must be taking place in underwriter's offices and the boardrooms of aircraft and engine manufacturers.
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Old 9th Feb 2013, 12:46
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I, too, flew the 145, same company and flew with Richard once or twice. Nice to hear that other companies are at least beginning to take the 145 odour problem seriously. Guess that I might count myself lucky to be symptom free.....
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Old 11th Feb 2013, 03:44
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hmmmmmmm

Had to take a few deaths to wake them up a little!
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Old 13th Feb 2013, 06:47
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The Economist Feb 7th

Air quality on planes: Aerotoxic syndrome | The Economist
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Old 13th Feb 2013, 08:10
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No evidence....

BA cites independent studies commissioned by Britainís Department for Transport which found "no evidence that pollutants occur in the cabin air at levels exceeding available health and safety standards".
As exposure levels from the 1940's and 50's were used and incredibly no fume event was published in the Cranfield study - it's true that levels were not exceeded - but it follows that conclusions are simply not valid, as per the following letter in 'Flight'.

http://www.aerotoxic.org/download/do...une%202011.pdf

This is the horsemeat of the airline industry and they know it.
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Old 15th Feb 2013, 16:23
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New film about this

Saw there is a new film being made about this by an ex BA pilot:

A Dark Reflection - Film - Home

Should be interesting
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Old 16th Feb 2013, 04:29
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Dr. Bagshaw is clearly an idiot and a corporate pawn. Ignore him.
(From an industrial hygienist.)
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Old 16th Feb 2013, 07:45
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Dr. Bagshaw is clearly an idiot and a corporate pawn. Ignore him.

I appreciate many here won't agree with Mike Bagshaw's comments but he certainly is not an "idiot".

The somewhat dated CV at the top of this document might give you some idea of where he is "coming from":

http://projects.bre.co.uk/envdiv/cab.../m_bagshaw.pdf

Last edited by wiggy; 16th Feb 2013 at 08:09.
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Old 16th Feb 2013, 09:32
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Paid doctor$

How any doctor can read the following FAA funded work:

'Exposure to aircraft bleed air contaminants among airline workers' - A Guide to Health Care Providers

http://www.aerotoxic.org/download/do...ocol031909.pdf

and then not understand how toxic oil fumes in a confined space make some people ill reminds me of this quote:

"It is difficult to get a man to understand something when his salary depends upon his not understanding it."

Upton Sinclair, 1936
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Old 16th Feb 2013, 10:00
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Until we can be satisfied that the UK has undertaken a proper study on this topic to establish whether there is a risk or not (cf Australia), and with acknowledgement to Upton Sinclair, I think the only way forward is to press for ALL aircrew to formally and properly report ANY suspected air contamination. The method of so doing needs to be properly established and I would have expected the multiple pilot and cabin crew unions to lead the way here. I would suggest that any 'odours' are relevant since their presence indicates the existence of some contaminant.

I can see nothing obvious on the IPA website and CHIRP appears to have no item since 2008. If BALPA appear to be exercising 'Nelson's eye' here (members need to ask!!), then we should press the cabin crew unions to agitate since it is their health that may well be in danger as well.
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Old 16th Feb 2013, 11:27
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On one particular Fokker 100 in our fleet, there is an oily odour that comes through the vents during the takeoff roll and lasts for around 5 mins after takeoff. This happens on EVERY takeoff.

Does this sound like something to be concerned about? It's been written up multiple times. Engineers clear the defect (on paper at least) by saying the hydraulic system oil was overfilled. However the odour is still there on the next takeoff!

Anyone else experienced something similar?
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Old 16th Feb 2013, 11:27
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Professional Pilots Union

The new Professional Pilots Union seem to be able to at least discuss the issue sensibly and give good advice, which is a start:

Cabin Air Quality

The Independent Pilots Association (IPA) has done much over the past 5 years to raise awareness of the issue, even to the point of sponsoring medical research. All IPA paying members have been kept well informed on CAQ.

I know which Union I would rather represent my health interests. No question.
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Old 16th Feb 2013, 12:08
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That's excellent. 2 of the three unions 'on side' - why is BALPA now apparently 'rubbishing' this? I see the PPU states that an ASR is 'required' for fumes - where is the source for this? Certainly a few more crews donning masks and declaring an emergency would speed things up a bit to get a serious look at it.

Anyone know is c/crew unions are concerned?
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