Talk:Bleed air

I've been working on the pro-contra section, although if you want to take a look at it and possibly edit it, go ahead! I've tried my best to be neutral, but if you see room for improvement, please enhance it. I'm still learning the Wikipedia ropes! --QuantumEleven 09:59, Nov 10, 2004 (UTC)

I edited the pro-con section a bit to eliminate some wordiness and replace noted weasel words like "skeptics say..." with more neutral diction identifying the cons of the bleedless systems without assigning the point of view to anyone specific. -IamTHEbrassMunky —Preceding unsigned comment added by 68.18.34.167 (talk) 19:01, 27 June 2010 (UTC)

Heating vs. pressurization

Actually, the main use of bleed air on modern aircraft is pressurization rather than heating. The ambient temperature at 40,000 ft is indeed -67 deg F, but the ambient pressure is only 2.36 psi. (Data from "Airplane Performance..." by Perkins & Hage, 1949)

Heating the cabin to 75 deg F is comparitively easy because the cabin is insulated and full of kilowatts of heat-producing people and electonics. Some airplanes even need to be cooled down during cruise instead of heated. Raising the air pressure from 2.36 psi to 11 psi (max cabin altitude) is the real duty of bleed air during cruise. Komodon 07:26, 30 Mar 2005 (UTC)

temp of bleed air ??

I suspect the 1000C and 1200C figures to be incorrect... The EXHAUST of a jet engine is under 800C, as far as I know... The bleed air from the a compressor stage would certainly have to be much cooler wouldn't it?

Yes, those figures are way off and the article contradicts itself (1200C vs. 300C). The 300C figure is on the high side but still accurate. It's not "superheated" by any means. --Mexcellent

bleed valves control stall and surge

Very new at this, would some mention of the use of engine bleed to control compressor stall or surge be justified? Oldspoonhead 12:52, 31 March 2006 (UTC)

On the same note, it might be worth mentioning the use of bleed air to provide turbine blade cooling. —Preceding unsigned comment added by 134.117.72.229 (talk) 20:51, 15 September 2008 (UTC)

New planes (Airbus 350/Boeing 787) to stop using bleed air

I believe we can consider modifying the comment about A350 not eliminating bleed air. As far as I can see on General_Electric_GEnx, A350 is being offered only with either the same engine as the 787 (which is bleed-less), or with Rolls-Royce_Trent#Trent_1700 (which is also bleed-less). (Although Factbites claims that Airbus is in talks about modifying both alternatives so that they still can supply bleed air for their A350) --Filik

Bleed air is also used to de-ice the articulations on slats and flaps, but one of the greatest problems is that there is also a limit to the amount of bleed-off from a turbine, this was why we introduced an APU in the first versions of the Harrier, because on that aircraft the bleed-off was very limited because of the amount of power used for take-off and manovering. I worked as a designer in Rolls-Royce and later with Boeing on varios aircraft. johnriggotte@hotail.com —Preceding unsigned comment added by 83.61.75.215 (talk) 13:37, 13 February 2009 (UTC)

New Documentary regarding toxic gas issues in cabin air

Documentary: http://www.welcomeaboardtoxicairlines.com/
More information about it: http://www.pprune.org/forums/showthread.php?t=317008&highlight=toxic+airlines
Conference in Norway: http://www.safe.no/dokumenter/konferanseprogram1.pdf --Filik

Yah, right "documentaries." All they document is the anecdotal claims of alleged "victims" of airliner cabin air. They do not document any science that can link cause and effect in a way that stands up by constant testing via the scientific method.

The alleged "toxic air syndrome" has been manufactured by two airline labor unions who have a powerful financial incentive to get their govts to recognize their claims of on-the-job injuries. EditorASC (talk) 19:26, 17 February 2010 (UTC)

How do you account for the 2006 Sarah Mackenzie Ross study? Thanks. Martinevans123 (talk) 20:11, 17 February 2010 (UTC)

Here is the link to her study conclusions:

http://www.ucl.ac.uk/clinical-psychology/Research-Groups/Neuro_Toxicology/COT_Report.pdf

Show me what in that document, proves any causal link between the alleged contaminated air and any findings in the examinations of those pilots (note that 9 pilots had to be excluded from the study, because they had medical or psychological disorders that could explain their alleged injuries). Note also, that the remaining pilots that were tested, were ALL from a group that had reported that they were injured by air contaminated by engine oil. That is known as "self selection," and is not a good scientific basis for selecting a group to be studied.

Thus the study starts out with a very unscientific bias, since it is not scientifically possible for anyone to know what is causing his alleged injuries. Classic Post Hoc anecdotal analysis. There was no double-blind comparison to other pilots or others that might have reported such alleged injuries, without thinking in advance that they were poisoned by bleed air. There is nothing in that study which establishes what might have contaminated the cabin air, if it was in fact contaminated. Nothing to eliminate formaldehyde, ozone, deicing fluid, improper mixing of toilet chemicals, passenger sources (in their carry-on bags), etc., all of which have actually happened, according to British reports. Nothing at all which could exclude other, not-on-the-job sources of possible brain and cell damage, in the biased-selected study group.

Studies which have been conducted on people who have been injured by the alleged toxic chemicals, concluded that every case, since 1943, involved exposures to quantities that were many times that which is contained in jet engine oil. There simply is no proof that any alleged cabin air "fume event" has ever caused anyone to breathe in dangerous chemicals in quantities that exceed known safe amounts. In the studies that have sampled cabin air, they never found any contamination that exceeded known safe levels. In fact, such research has consistently shown that airliner cabin air is typically of better quality than in many other work environments, such as office buildings. EditorASC (talk) 23:25, 1 April 2010 (UTC)

I have removed the criticism section in this article, as it was simply an attempt to use this article for the same kind of political agenda spam, as they tried to to with the Aerotoxic Syndrome article. I replaced that section with a "see also" link at the end of the article, that goes to the Aerotoxic Syndrome article, where that issue is discussed in the proper manner. If the advocates of AS want to prove their case, it should be done in that article, and not by spamming every possible other page in Wikipedia. EditorASC (talk) 15:40, 20 March 2010 (UTC)

Can you show us your evidence that the Mackenzie Ross study "has been manufactured by two airline labor unions who have a powerful financial incentive"? And you may want to check your link to the summary of findings [1], as it seems not to open. Thanks. Martinevans123 (talk) 08:33, 2 April 2010 (UTC)

But you raise some interesting points, Editor:

Self selection: - I don't think the hypothesis here is that "all bleed air from all aircraft will always damage all pilots". I think it's more a case of "some bleed air from some aircraft may sometimes damage some pilots". If so then self selection by self observed symptoms seems a reasonable way of reducing the subject pool to those for whom there is the most likely to have been a measurable effect. Bur we can look forward to the Retrospective Study of 1500 pilots 2007-2009 which is now in preparation by the NTU.

Post Hoc analysis: - could you explain how any researcher could find a group of counter-balancing pilots who will be unaware of the possibility of the toxic effects of bleed air?

Other pollutants: the "reports" that "formaldehyde, ozone, deicing fluid, improper mixing of toilet chemicals, passenger sources (in their carry-on bags), etc" seem to be simply some of the items in the list of possible contaminants in the COT service information leaflet. I agree that the Mackenzie Ross study made no attempt to exclude these. But nor would you expect such a small scale study to do this?

Previous studies: is your hypothesis that since toxic chemicals are at safe levels in engine oil, there can be no ill effects of long exposure from the product of bleed air mixed with this oil? I am also not sure that the hypothesis is that all damage is caused by noticeable "fume events".

Political agenda spam: - Could you explain why you consider the work of Mackenzie Ross at NTU to constitute "political agenda spam"?

Structure of article: - Your unilateral removal of all "criticism" seems to leave the article a little unbalanced, as aero toxic syndrome, whether real or not, is quite an important and relevant topic. I'm not sure that one single external link to Aerotoxic Syndrome in the "See also" section is sufficient.

Thanks. Martinevans123 (talk) 10:56, 2 April 2010 (UTC)

The report is NOT a research study, yet it is being touted by AA and affliated political agenda groups, and the popular press, as if it was a valid research study. Dr. Barnett has pointed out that the MacKenzie Ross paper is repeatedly being misconstrued and sensationalzied by AA advocates and the popular press. He has given several examples of such in his Aviation Week article. That MR paper itself warns against such improper use, with these words:

"Twenty seven aircrew have been assessed at UCL and our findings are contained within this report. It is important to note that we have undertaken a clinical audit of aircrew seen for clinical purposes. We have not undertaken a research study. Consequently, the sample we describe is self-selected and has not been compared to a matched control group of non-exposed aircrew (if such a group exists) and the conclusions that can be drawn from these findings have limitations."

That is on page two of that report, "A report for the Committee on Toxicity of Chemicals in Food, Consumer Products and the Environment. May 2006" [2]

Anyone trying to use it as if it is a valid scientific research study that proves any of the claims of AA, is guilty of deliberate distortion/deception, for what appears to be political purposes. EditorASC (talk) 23:34, 10 May 2010 (UTC)

I believe the Mackenzie Ross paper is a perfectly valid scientific research study, that should be judged on its own merits. So we need not add articles from "Aviation Week" or from any other secondary source as a reference. I am not interested in using the study for any "political purposes". It's just one relevant study. That's it. Martinevans123 (talk) 20:13, 13 May 2010 (UTC)

I agree with Martinevans123, this is an important and relevant topic and if some people don't believe in the Aerotoxic Syndrome issue or have some other motive, they shouldn't simply be doing what they can to discredit the issue. I've put back a Criticism and Ill Health Effects section to try and restore some balance to this article which otherwise sings the virtues of Bleed air. --TCP146 (talk) 11:51, 15 April 2010 (UTC)

Multiple spam linking

I am removing the Critism and Ill health sections since they constitute a renewed attempt to engage in multiple article link spamming. That is prohibited by the WP anti-spamming rules.

The Aerotoxic Syndrome article is the proper place to discuss that alleged medical syndrome, and not by spamming every possible other page in Wikipedia.

"Citation spamming is the illegitimate or improper use of citations, footnotes or references in a manner inconsistent with accepted standards. Citation spamming is a form of search engine optimization or promotion that typically involves the repeated insertion of a particular citation or reference in multiple articles by a single contributor. Often these are added not to verify article content but rather to populate numerous articles with a particular citation."

"Sometimes, people come to Wikipedia with the intention of spamming—creating articles which are mere advertisements or self-promotion, or spewing external links to a web site over many articles."

[[3]] EditorASC (talk) 23:47, 10 May 2010 (UTC)

Bleedless: Essay-style, outdated, and gets energy from Perpetual motion

It should be structured. The section "Use of bleed air" needs no subsections, but could and needs structure, too.

Best: Introduction shortened, too, and content moved to subsections.

Its outdated: 787 systems not fully covered: If you have less bleed air, electrical systems must replace it: Not fully described.

Does not list the increased need for batteries: No Perpetual motion existing. Seems to list mostly advantages of bleedless; also i think this will be the future in the next decades. Tagremover (talk) 13:51, 20 January 2013 (UTC)

Invalid Reference

Reference #1 is a broken link (^ Discussion paper on the cabin air environment, COT, 2006). Needs to be updated or removed. — Preceding unsigned comment added by Mtraskos (talk • contribs) 14:58, 12 December 2013 (UTC)

Improper nomenclature

I am reverting this well-intention edit by an IP editor

"Air can be "bled" from the compressor at any stage for various purposes including but not limited to, internal cooling of the engine, pressure reduction while starting or for any other purpose. Air that is bled from the engine for use in other than the engine is most correctly referred to as "Customer Bleed Air"

for these reasons:

a) The first part does not add anything to the article which is not already explained elsewhere.

b) The phrase "Customer Bleed Air" is not industry standard nomenclature. The few places that I can find any definitions of that phrase, do not consistently agree on what it means.

c) The source given as citation support (A You-Tube Video) does not meet WP:RS standards. Nor do the other rare sources on the Internet that mention it; they all seem to be wikis or blogs. None of these are acceptable as Wikipedia RS.

d) The gentleman in the You Tube video, while interesting, is not a known authority, nor does the video serve as a secondary reliable source. He often uses terms interchangeably in that video, which adds confusion, not clarity. An example would be his using the term "bleed air" while describing the function of Pressure Relief Valves, which have nothing to do with the first and second stage bleed air systems on modern airliner engines.

Adding a non-standard phrase like "Customer Bleed Air" does not clarify anything; it only adds confusion. EditorASC (talk) 13:49, 22 February 2014 (UTC)

Improper Edit Reversal

Well you are being rather pedantic. That in and of itself is not a bad thing per se; however, in this case it is since "bleed air" is a most confusing term and the gentleman in the video, whom I believe is certainly more then qualified as a reference on this subject and he does open by discussing the confusing nature of the term and then goes on do discuss it at length, describing the different ways and purposes compressor air is used, and ties the whole thing together rather nicely at the end. So we can go on and on reversing each others edits, or we can find the middle ground on this subject, which best describes the term, which is as evidenced by the nature of the phrase and the video. Hope your feeling better. — Preceding unsigned comment added by 99.75.94.206 (talk) 15:43, 22 February 2014 (UTC)

It is very rare that a You-Tube video qualifies as a reliable source, for citation purposes, according to Wikipedia rules. I have already stated that above, but because you apparently didn't bother to read WP:RS on that issue, I am now pasting it in here, so you can be confident that you cannot use that link to support any statement in Wikipedia:

"YouTube: YouTube and other video-sharing sites are generally not considered reliable sources because anyone can create or manipulate a video clip and upload without editorial oversight, just as with a self-published website. However, official channels of notable organisations, such as Monty Python's channel

", may be acceptable as primary sources if their authenticity can be confirmed, or as a secondary source if they can be trace to a reliable publisher. Videos may also be used as a convenience link for material originally published elsewhere. In all cases, care should be undertaken to ensure that the video is genuinely authorised by the copyright holder. Be careful not to link to material that is a copyright violation. In general, unless the video is not clearly marked as "official" with a name strongly identified with the notable publisher or source, best practice is to treat it as a copyright violation and not use it." [[4]]

Clearly, that You-Tube video does not meet the very rare exception standards, for a Wikipeida RS citation, so it has to be removed. I have no reason to suspect that you are willing to intentionally violate the rules in regards to what is WP:RS and what is not, so I am confident you will not attempt to restore that invalid citation link. EditorASC (talk) 19:39, 22 February 2014 (UTC)

Well, we could argue the point until dooms day but I will address your point of the video with the follow comments:

1. Clearly this is a dedicated youtube channel to all things gas turbine. 2. If you perused the rest of the channel you would have noted he has posted over 27 videos based upon watcher questions and has given cogent and informed answers to questions of various types. 3. If he does not know he is very up front about it. 4. And last but not least he is Canadian!

So while I don't want to get into a pissing context about this, I assert that his channel, and therefor the video in question meets or exceeds the standard as set forth and therefor reject your assertion to the contrary and declare my position most vehemently that it is in point of fact a valid reference.

Clearly we both care about the accuracy of the document in contention and we do appear to have reached a middle ground as so therefor I will not restore that particular reference however, I do not accede to your contention. I do not know of your qualifications in the matter but I am a licensed pilot. 99.75.94.206 (talk) 20:59, 22 February 2014 (UTC)

I am happy to know that neither one of wants to get into an edit war over this. That means I have been accurate so far in my judgment about your sincerity and intentions.

As to my qualifications, I have over 25.000 hours of flight time all the way from Cessna 150s, to five specific Captain's type ratings on Boeing jets, including the 777 and the 747-400. I also flew the DC-6, DC-8, DC-10 and the B-720. I have lost count of how many ground schools I have been thru, to obtain the required certifications to be assigned to fly various airliners. I can assure you that we had to know all the nuts and bolts on both piston and jet engines and that proper nomenclature was always required in our oral questions -- if we did not want to flunk those many exams.

That is why I was rather astounded at the sloppy use of jet engine nomenclature used by the fella that made that video. Pressure relief valves, which fluctuate from fully closed to various degrees of open, to prevent compressor stalls during various power outputs of the engine, are NEVER referred to as "bleed air valves" at least not in all of my 35 years in aviation, until now. Nor have I ever heard the phrase "Customer Bleed Air" before now. No Boeing or Douglas flight manual that I have had to learn from cover-to-cover, ever used such nomenclature. It might have been in limited use in "How To" maintenance manuals, but it never was part of the terms we learned when we had to know and fully understand how the high and low stage bleed air system worked. We had to know cold, every function on the plane that those two-stage bleed air systems powered. There was no distinction in nomenclature for uses for the engines as opposed to all other uses. We had to know what to do if any leaks were detected (fire hazard) in the bleed air system, or how to compensate (so as not to lose pressurization) if any one bleed air system failed entirely. Those emergency and irregular procedures were entirely separate from procedures we had to follow in the event of compressor stalls (which usually were caused by one or more faulty PRESSURE RELIEF VALVES).

I have removed the links to You-Tube and to Google Patents, because both violate the rules for RS citation links.

The remaining links present problems too for these reasons:

a) Any valid RS citation link must support the statement you are making. While all three of the remaining links have the phrase Customer bleed air in them, NONE of the three define what that phrase means. They only reference that phrase when describing how to make precise adjustments to those air systems (they are in a How To maintenance manual). I won't delete those two maintenance manual links for now, but if you want them to remain, then you will have to rewrite your sentence of:

"Air that is bled from the engine for use in other than the engine is most correctly referred to as "Customer Bleed Air" [1] [2] [3] as described in the references."

So that whatever those maintenance manual links say, will support whatever statement you make about bleed air. I suggest you start by eliminating "most correctly referred to as". I will wait for at least 24 hours to give you time to salvage the sentence by re-writing it so that whatever you have to say about "Customer bleed air" is actually supported by the links you supply. Providing a link that does not define what that phrase means, much less what YOU SAY it means, is not acceptable. You must supply a link that does more than just use that phrase, when the purposes of providing a link is to support what you have actually said about that phrase.

The third military link should be ditched too, since it directly contradicts what you have said as to the definition of "Customer bleed air." Besides that link providing maintenance instruction for military sound-reducing technology for ships and submarines (that bleed air is cooled with sea water), it says that kind of air is used to anti-ice the turbine engines and to aid in engine cross-bleed starting, which directly contradicts your "for use in other than the engine," statement.

I have thought about attempting to re-write your sentences myself, but frankly, I cannot figure out how to do that and still meet all 3 of the WP:RS requirements for valid citation links. So, I will wait for you to attempt it yourself; you might think of something that I have not come up with, that might salvage that passage.

In short, any links you supply MUST be valid WP:RS, and THEN, they also must support what you actually say about the meaning of that phrase, AND they cannot say anything that contradicts the statements you are providing about that kind of bleed air. If the links fail on any one of those 3 requirements, then they have to go. EditorASC (talk) 21:56, 22 February 2014 (UTC)

Re-Write of first section

I did a re-write of the first section to:

a) To eliminate a dead link, "COT"

b) Eliminate erroneous information, specifically the part that described the engine pressure relief valve system -- which is designed to prevent pressure in the forward compressor section of the engine from getting so high that it will cause engine compressor stalls -- which can quickly cause significant damage to a jet engine. That pressure RELIEF system, is NOT part of the bleed air system.

The purpose and design of that pressure relief system is just the OPPOSITE of the purpose and design of the bleed air system. One is designed to get rid of too much internal air in the engine, while the other is designed to create and maintain very hot and high pressure air at all times, as a source of power for various necessary functions on the aircraft. Thus, it is quite sloppy in the nomenclature dept to refer to the air being DUMPED overboard from the engine, to prevent over pressurization of the engine itself, as "bleed air."

c) To clarify how the bleed air system is powered by two automatically controlled valves, high and low stages, tapped off of the forward compressor section, so that hot, pressurized air can be maintained in the system at all times and properly regulated, to keep both the psi and the temperatures within allowable limits.

d) To eliminate the contradiction of what was said to be the meaning of "Customer Bleed Air." Since the statements in the Naval maintenance manual directly contradicted the statement of the IP editor that "Air that is bled from the engine for use in other than the engine it is bled from has been classified in various publications as "Customer Bleed Air," I either had to eliminate that citation, or to rewrite that statement so that the contradiction is eliminated. I chose the latter, since the IP editor felt strongly that citation should be retained. My best effort to achieve consensus and to avoid getting into an edit war.

Frankly, I do not see that a reference to "Customer Bleed Air" adds any useful or notable information to this article. If it was entirely up to me, I would just eliminate that phrase. But Wiki policy is to encourage compromise and consensus within limits, so I will not remove it outright, unless someone else tries to re-write it in a manner that brings back the contradiction. EditorASC (talk) 19:59, 23 February 2014 (UTC)

Ok, so your cite that is now #1 is someones website and in my opinion, does not meet the criteria that you set forth to disqualify one of my cites for the term "Customer Bleed Air" so you are misusing it to justify your particular definition of what bleed air is and is not. "can be used for internal cooling of the engine" is incorrect since it is, in point of fact, used to cool many parts of the engine.

You have now descended to the level of "Wikipedia Glitterati" and this is exemplified by your previous statement, " I will wait for at least 24 hours" in effect saying to me "You got 24 hours to satisfy ME before I change it to what I DEEM BE CORRECT". You might be and old 747 driver but whatever respect I might have had for you has now vanished. And people wonder why others don't contribute more. <le sigh> 99.75.94.206 (talk) 01:31, 24 February 2014 (UTC)

Response to this statement:

"Ok, so your cite that is now #1 is someones website and in my opinion, does not meet the criteria that you set forth to disqualify one of my cites for the term "Customer Bleed Air"

It is becoming painfully apparent that you are not reading the rules in WP:RS. So, I will excerpt a pertinent section for you:

"While specific facts may be taken from primary sources, secondary sources that present the same material are preferred. Large blocks of material based purely on primary sources should be avoided. All interpretive claims, analyses, or synthetic claims about primary sources must be referenced to a secondary source, rather than original analysis of the primary-source material by Wikipedia editors"

The website which I used as citation number one [5], has been around for many years and is an excellent "secondary source" training manual for various airliners, and in this case is based entirely on the Boeing flight training manual (which is the primary source). It fulfills the WP:RS instruction above, for what is the preferred type of citation (secondary source). It is not comparable in any way, to the You-Tube video you used, which WP:RS rejects as a valid RS.

Response to this statement:

"can be used for internal cooling of the engine" is incorrect since it is, in point of fact, used to cool many parts of the engine."

I cannot understand what you mean here. The internal cooling of the engine is but one of the many uses listed. I don't understand why you say it is incorrect. Are you claiming that bleed air is NOT used for internal engine cooling? If air from the bleed air system is used to cool many other parts of the engine, as you say, then it would seem that statement is correct. I have no objection to your trying to re-write that particular statement, to make it more precise, if you think it will clarify. That is what Wiki editors are supposed to do.

The main objection I had to using the Naval Military source, was that it CONTRADICTED your definition of the meaning of "Customer Bleed Air." That sources says CBA provides anti-icing for the gas turbine, and that contradicts your statement that CBA is air used only "for use in other than the engine." Clearly, turbine anti-icing is an ENGINE use, so your definition, which EXCLUDES all engine uses of bleed air, cannot be correct.

That is why I re-wrote your statement: Because your source CONTRADICTED, your definition and thus DID NOT support your statement. By re-writing, to eliminate that contradiction, that source now supports the revised statement and is thus valid.

I still think that the CBA phrase adds nothing useful or notable to this article and we would be better off to eliminate it entirely. But again, I can live with it if you do not try to define it in a way that contradicts your citation source. EditorASC (talk) 14:11, 24 February 2014 (UTC)

Additional "Customer Bleed Air" References

https://www.fas.org/man/dod-101/navy/docs/swos/eng/64b7-205.html http://www.google.com/patents/WO2013119520A1?cl=en http://www.easa.europa.eu/certification/type-certificates/docs/engines/EASA-TCDS-E.021_%28IM%29_GE_CF34--10E_series_engines-05-03012013.pdf http://mil-spec.tpub.com/MIL-E/MIL-E-8593A/MIL-E-8593A00103.htm — Preceding unsigned comment added by 99.75.94.206 (talk) 16:04, 22 February 2014 (UTC)

POV tag

I have added a POV tag to the Fume section. I notice that the above debate is over 5 years old, and it seems since then this section has grown more and more one-sided. I am far from an expert on the issue, but the section reads as very biased and negative to me. Could really use some attention! Air ♠ Combat _What's^{up, dog?} 09:56, 4 January 2016 (UTC)

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