B737NG “PACK” NNC
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I'll admit to one "error" and that is the choice of word "sticky". English is not my first language of the 5 I speak. "Stuffy" would perhaps have been a better choice. 
It's like the air is standing still in the cabin (it won't be standing still, but move too slowly). Lowering the temperature won't help, except cold stuffy air seems more comfortable than normal temperature. Still the O2/CO2 levels will be uncomfortable (but not in anyway dangerous), which may make pax and cabin crew tired/cause headache etc. Like I compared already, it's like being a lot of people in a small room without opening the window occasionally to let in fresh air.
I missed the backtrack of the century!
In other words, the recirculation fans are only there for pax comfort. They change absolutely squad about packs output. Of course you can actively switch the packs to high flow, I prefer to leave the recirculation fans on.
It's like the air is standing still in the cabin (it won't be standing still, but move too slowly). Lowering the temperature won't help, except cold stuffy air seems more comfortable than normal temperature. Still the O2/CO2 levels will be uncomfortable (but not in anyway dangerous), which may make pax and cabin crew tired/cause headache etc. Like I compared already, it's like being a lot of people in a small room without opening the window occasionally to let in fresh air.
I missed the backtrack of the century!
Ah, so now you tell me....
So I see,your aircraft are junk,you cant use packs in high,and you dont want to cool the cabin,then you wonder why its sticky indeed.....marvelous
So I see,your aircraft are junk,you cant use packs in high,and you dont want to cool the cabin,then you wonder why its sticky indeed.....marvelous
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Ahh, back at home in India?
Quote:
they built it to meet the recirculation output of the packs
they built it to meet the recirculation output of the packs
Get it?
The air that is recirculated come from the packs,no???
No, it comes from the cabin and the E&E compartment.... Back to the manuals son.
No, it comes from the cabin and the E&E compartment.... Back to the manuals son.
Your air that the packs gave was reused by the recirc fans so yes it is recirculated!
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You write the packs..
They are there to ensure sufficient airflow through the cabin at all levels.
Man, you're confused.
As cabin altitude increases, the pack valve is biased to supply a lower airflow rate
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In any case, recirculation fans off, doesn't increase pack load and subsequent fuel consumption (you won't find anything about increased fuel consumption in the MEL either). But if the aircraft is full, your cabin crew will most likely complain that they can't breathe in the cabin and ask you to turn the temperature down, even by normal temps (as they can't find any other reasonable explanation for the sticky air).
I tell you use the ACM to cool the cabin then you reply that you cant use packs in high.
I write that your aircraft are junk,you dont use high mode or cool the cabin....then you write:wait for it:
In other words, the recirculation fans are only there for pax comfort. They change absolutely squad about packs output. Of course you can actively switch the packs to high flow, I prefer to leave the recirculation fans on.
You write the packs..
Quote:
They are there to ensure sufficient airflow through the cabin at all levels.
No, I wrote that "the Recirculation Fans are there to...", not the pack.
Quote:
They are there to ensure sufficient airflow through the cabin at all levels.
No, I wrote that "the Recirculation Fans are there to...", not the pack.
As usual you are writing BS. The packs doesn't recirculate anything. And it has nothing to do with service ceiling. You are so full of crap, it unbelievable that you are truly a pilot. They are there to ensure sufficient airflow through the cabin at all levels. It has nothing to do with pressurization,
completely independent from position of recirculation fan switches. I don't know how you got those two thing mixed together
Cabin ventilation gets air (airflow) from recirc fans and packs via the mix manifold..right??
As cabin altitude increases,airflow of PACKS is decreasing below its optimum,the recirc fans airflow helps such ventilation to keep the cabin optimum ventilation.(yes in ventilation,there is recirculated air from the packs(indirectly i give you that,as it is reused/recirculated by the fans).
Get it?
English is not my first language of the 5 I speak.
You should ask the questions on this board and not answer them as you are usually wrong.
there is probably a reason that you can only find a job in China,
You are so full of crap, it unbelievable that you are truly a pilot.
That's because you are less fortunately gifted, that this baffles you.
Back to the manuals son.
Listen, you obviously have no grasp of these things.
1/ Cosmo is a troll
2/ There is someone out there flying unsuspecting passengers around who has serious identity based emotional issues.
If it is possibility 2 and you recognise it Cosmo, PM me and I will try to help. My father is a very intelligent man but due to certain childhood occurrences and a couple of unlucky breaks later in life he went down the very unhealthy road of finding his own ' self worth' , or 'value' , in being correct when others were wrong. It was very sad to watch but it is something that can be worked through. I have seen it first hand and the relief as the charade is dropped (over time ) is huge for the individual involved, a normal life can be lived.
If it is possibility 1, crack on mate, very very well done
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Kramer for your records:
You wrote :
1)I write nonsense
2)Im a wise ass
3)i am wrong
4)I couldnt find a job due to my knowledge,ability to read and attitude.(that was a funny one as i spent quite a few years there)
5)I am writing bull ****
6)I am full of crap
7)If i am back in India,pejorative,condescending tone,,,i guess for the Indian pilots.
8)that im confused......yes i was with some of your sentences...
In turn i wrote that you are must be high and that you are an idiot.
Keep this in your files as a retrospect next time you preach someone about his verbal/written CRM skills.
You wrote :
1)I write nonsense
2)Im a wise ass
3)i am wrong
4)I couldnt find a job due to my knowledge,ability to read and attitude.(that was a funny one as i spent quite a few years there)
5)I am writing bull ****
6)I am full of crap
7)If i am back in India,pejorative,condescending tone,,,i guess for the Indian pilots.
8)that im confused......yes i was with some of your sentences...
In turn i wrote that you are must be high and that you are an idiot.
Keep this in your files as a retrospect next time you preach someone about his verbal/written CRM skills.
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Thank you for your input Framer, I tend to respond like that when being insulted by nitwits... I see you are trying to put me in a bad light, I don't like your either.
When someone clearly in the wrong, uses "", tells me to read my manuals, generally in a condescending tone and calls me stupid and an idiot, I fight back. Although more eloquently, thanks for highlighting the best ones. 
Lord Spandex Masher, bang on the money!!!
Yes I "got it" from my first post in the thread:
It seems like your backtrack is nearing it's completion. Now you just have to admit that....
If the recirculation fans are switched off:
1) The pack output doesn't change (obviously there will instead be less output from the mix manifold, which is what I have been saying all along)
2) Hence, there is no increase in bleed demand
3) Hence, there is no increase in fuel flow
Really, last time I even provided you with photo evidence (the max altitude discussion). You just disappeared from the discussion. I assume you will do the same this time.
When someone clearly in the wrong, uses "
", tells me to read my manuals, generally in a condescending tone and calls me stupid and an idiot, I fight back. Although more eloquently, thanks for highlighting the best ones. Lord Spandex Masher, bang on the money!!!
Cabin ventilation gets air (airflow) from recirc fans and packs via the mix manifold..right??
As cabin altitude increases,airflow of PACKS is decreasing below its optimum,the recirc fans airflow helps such ventilation to keep the cabin optimum ventilation.(yes in ventilation,there is recirculated air from the packs(indirectly i give you that,as it is reused/recirculated by the fans).
As cabin altitude increases,airflow of PACKS is decreasing below its optimum,the recirc fans airflow helps such ventilation to keep the cabin optimum ventilation.(yes in ventilation,there is recirculated air from the packs(indirectly i give you that,as it is reused/recirculated by the fans).
Recirculation fans have no effect on pack workload. It's myth and poorly written in the FCOM.
With recirculation fans OFF, the airflow in the cabin is below what is required for certification, but it doesn't change the workload on the pack.
With recirculation fans OFF, the airflow in the cabin is below what is required for certification, but it doesn't change the workload on the pack.
If the recirculation fans are switched off:
1) The pack output doesn't change (obviously there will instead be less output from the mix manifold, which is what I have been saying all along)
2) Hence, there is no increase in bleed demand
3) Hence, there is no increase in fuel flow
Defacto:
If you prove me wrong with facts/docs rather than pure say then yes ill mea culpa anytime...even with you...
If you prove me wrong with facts/docs rather than pure say then yes ill mea culpa anytime...even with you...
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Aye aye aye aye
WRONG,it has a scheduled output,an optimum but it reduces as the cabin goes higher.
Here is an explanation of how the pack reduces its airflow as cabin altitude increases.
Again AMM:
The recirculation help in this condition by increasing airflow,ventilation at higher cabin altitudes!
As cabin altitude increases,packs that need to keep as close to an optimum air flow,let more bleed into the upstream sense port.
More bleed means more fuel..as minimal as it is..
How about it?you like to fly with close to max,at max or above? What was it?
The pack output doesn't change
Here is an explanation of how the pack reduces its airflow as cabin altitude increases.
Again AMM:
The high flow servo is selected when solenoid “B” is de-energized, low flow is selected when solenoid “B” is energized. As cabin altitude increases, a bellows expands and biases the servo spring balance to produce a lower airflow rate.
As cabin altitude increases,packs that need to keep as close to an optimum air flow,let more bleed into the upstream sense port.
More bleed means more fuel..as minimal as it is..
Really, last time I even provided you with photo evidence (the max altitude discussion). You just disappeared from the discussion. I assume you will do the same this time
Last edited by de facto; 17th Sep 2014 at 12:05.
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As cabin altitude increases, a bellows expands and biases the servo spring balance to produce a lower airflow rate.
Next time you fly, do the checks Lord Spandex Masher suggested. Maybe they are simulated in MSFS too.
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The will continue their schedule no matter what you do with the recirculation fans...
Was your comment :
Quote:The pack output doesn't change
It was wrong and now you get it right?
Good,so now you agree the pack airflow rate decreases at high altitude (after all it is only the AMM).
What you dont get into your head is that a lower flow is sensed by the pack via these bellows as the pack is directly connected to the mix manifold.
As the fans are off,and the cabin is high,the pack flow rate (systematically/biased to reduce) as cabin increase,a lower flow is sensed by the pack which opens its upstream port to let in more bleed air....
I was looking for your max altitude thingy (which i hope you will explain where i was wrong and again im ready for mea culpa...by wrong i dont mean in disagreement with you,obviously) i found this about recirc fans in pprune...the poster "yeelep" is a mechanic on 737:
Question was:
RMC, that's a poor justification for a couple of reasons. One, even with the recirc. fans on, the left pack is the source of air to the flightdeck. Two,the recirc. fans draw air through HEPA filters.
Quote:
On the other side of the coin can someone confirm that with the fans off no recirculation would mean a greater bleed offtake (slightly higher fuel consumption).
Yes.
Quote:
On the other side of the coin can someone confirm that with the fans off no recirculation would mean a greater bleed offtake (slightly higher fuel consumption).
Yes.
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de facto and cosmo kramer, please, STOP having this stupid "I'm right and you're wrong" match on here.
You BOTH act like children not older than those in pre-school!
Keep it factual, provide evidence based proof to the conversation and refrain from having a dig at each other or others for that case.
A Professional Pilots Rumour Network has NO place for adolescent behaviour like you display here.
You are both providing the same quotes repeatedly, we've seen them, read them, and tried to digest your inputs, like we do those of others providing similar.
You BOTH act like children not older than those in pre-school!
Keep it factual, provide evidence based proof to the conversation and refrain from having a dig at each other or others for that case.
A Professional Pilots Rumour Network has NO place for adolescent behaviour like you display here.
You are both providing the same quotes repeatedly, we've seen them, read them, and tried to digest your inputs, like we do those of others providing similar.
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You are right Skyjob, to anyone reading this thread please accept my apologies of being sucked into discussing with that moron...
For the benefit of other reading the thread, a bellows is a small pressure sensitive bag. The 737 is a crude and much mechanical aircraft. And so is a bellows. Where exactly these are located, I won't play wise and say that I know. They could be on the pack in the pack bay and use outside air pressure to deduct the expected cabin altitude, or the could be remote from the pack (doubt it as according to DeFacto's quote, the bellows is connected with the servo spring).
Even if we were to assume that they are somehow sensing the pressure in the cabin, like DeFacto claims, it doesn't change a damn thing.
Since recirculation fans have nothing to do with pressurization, which I mentioned several posts back already. On or Off, the pressure remains the same in the cabin, outflow valve won't change position. Because the recirculation fans are not adding any air mass to the inside of the aircraft, neither are they removing anything when off.
In the most basic terms, the recirculation fans are like buying two standing fans, and placing them in the aisle of the aircraft. They are just there to keep the air in motion in the cabin.
For the benefit of other reading the thread, a bellows is a small pressure sensitive bag. The 737 is a crude and much mechanical aircraft. And so is a bellows. Where exactly these are located, I won't play wise and say that I know. They could be on the pack in the pack bay and use outside air pressure to deduct the expected cabin altitude, or the could be remote from the pack (doubt it as according to DeFacto's quote, the bellows is connected with the servo spring).
Even if we were to assume that they are somehow sensing the pressure in the cabin, like DeFacto claims, it doesn't change a damn thing.
Since recirculation fans have nothing to do with pressurization, which I mentioned several posts back already. On or Off, the pressure remains the same in the cabin, outflow valve won't change position. Because the recirculation fans are not adding any air mass to the inside of the aircraft, neither are they removing anything when off.In the most basic terms, the recirculation fans are like buying two standing fans, and placing them in the aisle of the aircraft. They are just there to keep the air in motion in the cabin.
Last edited by cosmo kramer; 17th Sep 2014 at 14:19.
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Skyjob,
As you will notice as you digest through our posts and kramer constant and latest insult above,that my posts are using technical information from the AMM rather than basic say.(not sure what other info i can use to explain my idea,.and yes Kramer the Pack assemply gets input from actual cabin altitude.Id send you pictures of the pack assemply diagram and its link to the mix manifold but the latest naming did it.
Im ready to be explained otherwise..maintenance input accepted,just not by arguments such as
recirc fans blow air in the cabin like in a car and packs pressurize the aircraft.
Im done here..as all i had to contribute was written on this subject.
Keep it factual, provide evidence based proof to the conversation and refrain from having a dig at each other or others for that case.
Im ready to be explained otherwise..maintenance input accepted,just not by arguments such as
recirc fans blow air in the cabin like in a car and packs pressurize the aircraft.
Im done here..as all i had to contribute was written on this subject.
Last edited by de facto; 17th Sep 2014 at 14:57.
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I knew you would back out!
We can stop the guesswork, as I have a diagram too from the AMM:
The bellows do indeed have sense ports direct from the cabin. But as clearly visible it all takes place prior to the mix manifold. Hence, it is all exactly as I have been saying. The pack doesn't care what is going on in the mix manifold (I.e. If the recirculation fans are on or off).
The pack will deliver their fixed flow (biased for cabin altitude) and the outflow valve will adjust to maintain pressure accordingly.
The only responsibility of the recirculation fans is to... wait for it... recirculate the air in the cabin.
We can stop the guesswork, as I have a diagram too from the AMM:
The bellows do indeed have sense ports direct from the cabin. But as clearly visible it all takes place prior to the mix manifold. Hence, it is all exactly as I have been saying. The pack doesn't care what is going on in the mix manifold (I.e. If the recirculation fans are on or off).
The pack will deliver their fixed flow (biased for cabin altitude) and the outflow valve will adjust to maintain pressure accordingly.
The only responsibility of the recirculation fans is to... wait for it... recirculate the air in the cabin.
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Having (after commenting on not to have a you're wrong I'm right match on here) taken the time to read through the AMM for my own reassurance of system knowledge and for the benefit of ALL readers here not having access to this document, the following extracts, make of them what you want:
AIR CONDITIONING - DISTRIBUTION - INTRODUCTION
Recirculation System
The recirculation system permits ventilation of air in the passenger cabin areas. The recirculation system decreases the use of engine bleed air. This enables better thrust management and decreases fuel consumption.
Recirculation System
The recirculation system permits ventilation of air in the passenger cabin areas. The recirculation system decreases the use of engine bleed air. This enables better thrust management and decreases fuel consumption.
AIR CONDITIONING - DISTRIBUTION - GENERAL DESCRIPTION
Recirculation System
The recirculation system uses two fans to move air from the passenger compartment to the mix manifold. This system reduces the amount of air that the packs need to supply.
Recirculation System
The recirculation system uses two fans to move air from the passenger compartment to the mix manifold. This system reduces the amount of air that the packs need to supply.
AIR CONDITIONING - RECIRCULATION SYSTEM - INTRODUCTION
Purpose
The recirculation system supplies air for ventilation. The use of cabin air for ventilation decreases the use of air from the engine bleed system.
General Description
The recirculation system collects cabin air to use with pack air in the distribution system. The distribution system supplies air to the passenger compartment area.
Operation
The recirculation fans are enabled when you move the RECIRC FAN switches to the AUTO position. Recirculation fan operation depends on air conditioning pack operation.
Purpose
The recirculation system supplies air for ventilation. The use of cabin air for ventilation decreases the use of air from the engine bleed system.
General Description
The recirculation system collects cabin air to use with pack air in the distribution system. The distribution system supplies air to the passenger compartment area.
Operation
The recirculation fans are enabled when you move the RECIRC FAN switches to the AUTO position. Recirculation fan operation depends on air conditioning pack operation.
AIR CONDITIONING - RECIRCULATION SYSTEM - RECIRCULATION FAN
Functional Description
The recirculation fans pull air in from the passenger cabin and supply it into the main distribution manifold.
The right recirculation fan pulls in air from the collector shroud in the forward cargo compartment.
Floor grilles in the passenger compartment permit airflow into the collector shroud.
The left recirculation fan pulls in air from the distribution compartment.
Functional Description
The recirculation fans pull air in from the passenger cabin and supply it into the main distribution manifold.
The right recirculation fan pulls in air from the collector shroud in the forward cargo compartment.
Floor grilles in the passenger compartment permit airflow into the collector shroud.
The left recirculation fan pulls in air from the distribution compartment.
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Here is one more:
So, it's great the system is there, as we would otherwise have poor ventilation of the cabin... same goes if you turn it off.
Recirculation
This part of the A/C system recycles approximately 50 percent of the cabin air for ventilation purposes. This reduces the quantity of fresh air from the pneumatic system for ventilation. The left and right recirculation fans and filters are the primary components.
This part of the A/C system recycles approximately 50 percent of the cabin air for ventilation purposes. This reduces the quantity of fresh air from the pneumatic system for ventilation. The left and right recirculation fans and filters are the primary components.
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Cosmo, we ALL know it recycles the air, it's what it is designed for.
But similarly it reduces fuel by reducing output from the packs.
Not a direct correlation but an indirect effect of the system.
But similarly it reduces fuel by reducing output from the packs.
Not a direct correlation but an indirect effect of the system.
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Skyjob,as i wrote:
As of now,my boeing technical pilot source(boeing team) seems to agree that an increase in bleed demand for same thrust setting,(pack work load increases as less cool air into the manifold,therefore an indirect increase in fuel consumption due to the recirc fans off.
He will ask confirmation to his ops engineering and will get back to me in the morning.
Concerning the original question,why during both pack remaining illuminated,the kept fan is off and right fan is left in auto,he will confirm it tomorrow as well.
Concerning :
Boeing guy wrote:
Did i write that the fans influence the packs flow schedule directly?NO, but indirectly yes.
He will ask confirmation to his ops engineering and will get back to me in the morning.
Concerning the original question,why during both pack remaining illuminated,the kept fan is off and right fan is left in auto,he will confirm it tomorrow as well.
Concerning :
It's like the air is standing still in the cabin (it won't be standing still, but move too slowly). Lowering the temperature won't help, except cold stuffy air seems more comfortable than normal temperature. Still the O2/CO2 levels will be uncomfortable (but not in anyway dangerous), which may make pax and cabin crew tired/cause headache etc. Like I compared already, it's like being a lot of people in a small room without opening the window occasionally to let in fresh air.
Selecting recirculation fan (s) off will result in lower cabin humidity levels, but the total fresh air remains unchanged unless the packs are selected to HIGH flow. Also, cabin temperature gradients may be affected by selecting the recirc fans off inflight. Selecting the recirc fans off may prevent the cabin air from circulating in the normal manner, creating pockets of slightly colder areas within the cabin. Selecting high flow will not necessarily improve this situation