A320 pack flow LO when pax >115

[DesiPilot]

Wanted to find out something from the A320 Guru’s!!

Our company just came out with a policy to keep the pack flow to low regardless of number of pax travelling. Usually our flights are full (180 pax).

I understand that at LO setting it is 80% of normal and if the temperature demand cannot be met it reverts back to Normal (100%). But there is no mention of quality of air, what if the temperature demand can be met, is 80% flow is adequate for 180 pax? There has to be a good logical reason why A320 FCTM says to use pack flow to LO when pax load is less than 115.

Any comments?

[subsonic69]

thats a good question..

maybe your company thinks that when you set it at LO, they'll start to save some fuel and also lessens the stress on the ACM ...

other than that.. I dont know ... need a refresher i guess.:ouch:

[HAWK21M]

What would be the volume rate of air flow on Hi & Lo mode on an A320 approx?
regds
MEL.

[Airbus_a321]

I was told savings in LOW, used only with 116 pax or less, should be 0.4% of the trip fuel.

[hetfield]

Our company just came out with a policy to keep the pack flow to low regardless of number of pax travelling.

Did they shut the aircond in their cozy offices down as well?

[Old Fella]

If the pax start complaining about "stuffy" conditions the company might just loose out on any fuel saving achieved by using the LO setting. However, as another poster alluded to, the bean counters won't know, or care, from their fully air conditioned office.

[LYKA]

Depending on which part of the world you are located (e.g., EU) LO flow does not comply with the fresh air circulation regulations, hence the Airbus PAX information in the FCOM.

ATB

[DesiPilot]

Depending on which part of the world you are located (e.g., EU) LO flow does not comply with the fresh air circulation regulations, hence the Airbus PAX information in the FCOM.

ATB

Well, I am in India, so I highly doubt there is any regulation for fresh air circulation. Yes, I am worried about the pax but more than that I am worried about myself, four sectors a day with almost all flights full; So seven hours in the tube with pack flow to LO worries me a little.

I have written an email to ops dept, will let you know of the results/answer.

[toby320]

hi, in my company we have same policy and this obey direct for saving fuel, but as far as I know the demand of air inside not respect the position of this LO switch so at the end I don't think they will be saving the fuel that they want.

[LYKA]

It is not possible to comply with the fresh (outside) air requirement of 10CFM/per person of FAR 25.831(a), Amdt 25-87 when ECON or LO flow is selected in conjunction with a full passenger load. This is one of the reasons that the FCOM only allows selection of ECON or LO flow with reduced passenger loads. The ECS flow rates are sized in relation to the airworthiness requirements and also to ensure good temperature control and ensure that bio-effluent levels do not cause the cabin to appear stuffy. The main indicator for bioeffluent is carbon dioxide which itself is the subject of airworthiness regulation FAR §25.831 (b2), Amdt. 25-89: “Carbon dioxide concentration during flight must be shown not to exceed 0.5% by volume (sea level equivalent) in compartments normally occupied by passengers or crew members.” and JAR §25.831 (b2): “Carbon dioxide in excess of 3% by
volume (sea level equivalent) is considered hazardous…The level of carbon Dioxide in the cabin is dictated only by outside airflow, cabin volume and the
generation of carbon dioxide by the passengers, i.e. recirculation flow rate does not help in this case. Therefore, reducing fresh air flows below the existing levels by selecting ECON or LO flow outside of the FCOM limits can cause an increase in carbon dioxide, which can cause the cabin to feel stuffy and in the worst scenario break the carbon dioxide airworthiness regulations.
In summary, Airbus does not recommend selection of low pack flow outside of the FCOM limits, due to the possibility of non-compliance with the airworthiness regulations, a possible increase in bioeffluent levels causing a degradation in cabin comfort and the possibility of reduced temperature control efficiency.