Packs in Cruise
 

Dear Everybody!

Can you enlighten me as to your companies' SOP regarding Pack usage in cruise?

Do any of you regularly turn off packs to save fuel? Can't do it anyway on an aircraft with only two packs.. or can you?


Thanks in advance.

OORW

Reduced Packs
 

I think that quite apart from any SOP or safety consideration it would be imprudent to close down a pack as a way of reducing fuel burn rates because of the effect on the paying passenger comfort. Used to use 1/2 pack flow on the Classic at times, however this led to a stuffy environment in the aircraft due to the reduced outflow, especially on high pax density loads. Shutting down a pack is not something I would use to save fuel, much rather cruise at best level/best speed for weight in the prevailing ambient conditions. :ok:

We change the pack flow when the loads are lite, below 100 on the A320 or 140 on the A321. We have no SOP to turn off packs in flight. I don't think that type of operation would fly where I'm at.

On the 747 Classics that didn't have the half flow option, we used to shut down one aircon pack as normal ops in cruise (and close the heat exchanger air inlet door for that pack), and restart it just prior to descent...never a problem!

For those that are not aware, the 747 Classic had three packs and a flight engineer to operate all these fiddly bits, all very good things to have!

Flew them for years that way...

Cheers...FD...:ok:

Others may disagree, but having only two packs and shutting one down to save money borders on gross negligence.

I'll disagree because that's wrong - You do it to save fuel, and that's for yourself. It's nothing to do with money at all.

Great!

Many thanks for all your replies!

OORW

Gross negligence, yes indeed.
If one air conditioning pack (on a two pack aeroplane) were to be shutdown as a fuel saving measure, and then the other pack were to fail for some reason, re-starting the shutdown pack would be required.
Meanwhile, the cabin pressurization would be greatly affected....and if the intentionally shutdown pack was to not re-start, a high dive is assured.

The fleet manager would not be amused, pilot dismissal time, I would think.
Regulatory action might well follow.

On my current aircraft, which only has two packs, we regularly fly with only one pack on. This is with the knowledge and approval of the local regulators.

The aircraft can also be dispatched with only one pack operative without restrictions.

Shutting down packs
 

Breecher, would be interested to know for whom you fly and which regulator accepts single pack operation as a matter of course, just so I don't fly your airline. :eek:

Hear, Hear....Old Fella!

The rules governing single pack operation are quite clear, and Breecher is a breacher of those safety-related rules!

Cheers...FD...:=

PS: Maybe he has removed the plug to let the water out of his little boat, saves having to bail the water!

Shutting down 1 pack on a 2 Pack aircraft to save fuel....

Ok on 767 A330 etc when you are in cruise with 2 packs operating. The pack out put is aroung 60%. Built in fuel saving by manufacturer.

If you lose a Pack the servicable Pack 767 defaults to 146% flow and the A330 goes to High flow (not sure of the figure but is similar). regardles of "high flow" switch position

So staright away your bleed loads are higher ... therefore higher fuel burn with 1 Pack running.

It will take a clever aerodynamicist to tell us whether the reduced drag due to 1 Packs cooling doors closed will compensate for the added fuel burn due to higher bleed loads. :ok:

A slight change in Breecher's wording and the Australian regulator allows it.

On my current aircraft, which only has two packs, we sometimes fly with only one pack on. The aircraft can be dispatched with only one pack operative with restrictions.
This is with the knowledge and approval of the local regulators.

Dash 8, BAe146, B717 + many more I am sure.

Inoperatve Pack
 

RENUPP, thanks for clarifying Breecher's post. We are all aware that the MEL would permit despatch with one pack inop, with restrictions. I would be amazed if the regulator would condone the practice of shutting down one pack as a fuel saving measure as a SOP. Thanks too, to Bolty McBolt for the info on how the B767 and A330 automatically reschedule mass flow in the event of a pack shutting down.

Our MEL also allows us to fly around for ten days with a brake deactivated, with restrictions, I believe the regulators did this to aid the operator in returning the aircraft back to base, not to save on wear and tear on one set of brakes. :ugh:

why not shutting down an engine to save fuel now?
what is the saving having one Pack in HI flow instead two in low?
DO you consider the stress associated to the only pack performing?

MEL
 

I think we are all aware that some operators seem to see the time granted in MELs as targets, and not as an absolute maximum time granted to get something repaired. Same with Duty hours, service intervals, and, and, and..

Back to thread: what Aircraft, beside the 747 old and new have more than two Packs? I cant think of any, except older aircraft like the 707 and similar.

OORW

Don't confuse potential engine bleed sources versus number of packs.

B707, two packs only, one pack dispatch OK (not long overwater) however altitude restrictions apply.

L1011, three packs installed and normally used, two pack dispatch OK, no restrictions.

This was once proposed by DanAir while they were operating Comets, but the ARB nixed the idea, pronto.

Quote 411A: B707, two packs only, one pack dispatch OK (not long overwater) however altitude restrictions apply.

.. I stand corrected!

OORW

On the Airbus 340/330,when 1 pack is off or when the packs are supplied by the APU bleed,the pack flow automatically goes to high which results in an increased fuel burn of upto 1.5 percent.On a long haul flight with a burnoff of 90,000kgs this is quite a substantial amount!In my opinion,the only safe and prudent way of saving fuel is 1)landing in config3 (reduced landing flap config) 2)shutting 2 engines down on the 340 or 1 engine on the 330 after landing 3)where possible,idle reversethrust.

Switching a pack off in flight increases your fuel burn substancialy,well,at least as far as airbuses are concerned!:)

I say again for those who didn't get it the first time.
On my current aircraft there are no restrictions on single pack operation. None, zip, zilch, nada.

It's interesting to see all the indignation and accusations coming from people, without anyone even knowing what type of aircraft or operation I am talking about.

Jumping to conclusions or knee-jerk reactions from people who should know better.

Well why don't you just tell us then?

Well, on my little J31s we use both packs all the time. There are however no checks that both packs are working - either the cabin maintains the correct altitude or it doesn't. Thus in the cruise, I used to slowly reduce the flow from one of the packs and watch the cabin altitude instrumentation. As one pack is capapble of maintaining the correct cabin altitude, I expected to see no change in this. With the correct cabin altitude maintained with one pack turned off, I slowly re-established the flow and then repeated the exercise on the other. From time to time, this would cause the cabin altitude to start to climb. The flow was thus restored immediately, and he failed pack put U/S at the end of the flight.
I found it comforting to know that both my packs were working - thus reducing the passenger discomfort which would otherwise ensue if the only working pack failed unexpectedly in flight!

P.P.

MD 11 Dc10 have 3 packs,the MD11 all controlled by the ESC,ESC decides what pack runs(generally 3 ,unless in manual) ,after recieving various inputs from sensors,amount of pax etc. DC10 has a panel operator who does the job in place of the ESC,on frieghters he usually just runs 2 packs.

The number of operating packs in cruise has more to do with revenue passengers' comfort than about saving fuel!

With 400+ breathing, heat generating pax in the cabin it's more about cabin air exchange rate [fresh air flow] than it would be, for example, when flying boxes in a freighter with only crew.

. . . Or will you be explaining to First Class passengers who fork over $4000 each for a seat why the cabin feels stuffy? . . . Because your company wants you to reduce cabin air flow to save fuel...? :ooh:

18-Wheeler reveals a new paradigm: How's that again?? :confused:

Have a think about it, from the Captain's point of view.

If a CPT isn't thinking about the cost of his actions, ... :{

In a twin, single-pack operation up to FL250 could be an acceptable risk, though I would not volunteer for it unless it was a written order from the boss. Another way of saving fuel, but again I would not do it unless directed, would be to reduce the cabin diff by running the cabin alt at 10,000ft. That one is good for an old airframe too.

Packs and the 747-200/300s
 

Most of newer generation (yet now old) 747-200/300s were produced with 3 packs, except the 200Fs which were designed with only 2 packs for specific cargo operations. I also recall old (very old) 747-100s that I flew, that were keeping good cabin altitude on only 1 pack, at say FL 350...
xxx
What we do nowadays - with our 747-200s in passenger operations, is to cruise with one pack in full flow and one other pack in "half-flow" with low passenger loads, or two packs when we have a full cabin daylight flight.
xxx
I have flown with cargo planes - often these were dry leased, converted passenger aircraft which had 3 packs, with the nº 2 pack conveniently labeled INOP (to save on maintenance) - yet, that nº 2 pack turned out to be fully operational - funny, they did not remove the pack all together to save on weight. I wish the INOP status was fully documented to crews.
xxx
As to minimum dispatch MEL considerations, yes, we say - passenger airplanes must be dispatched with 2 operating packs, and we can depart with 1 pack if cargo flight, or if operating a passenger aircraft at/below FL 250.
xxx
The idea of running a passenger aircraft with high cabin altitude (low PSI differential) is often considered. On "wild" charter flights with a bunch of drunks returning from a football/soccer game - or with children excited by their Disneyworld visit, we experiment running the cabin at 9,500 ft altitude. This puts everyone to sleep to the satisfaction of the cabin staff... After all, people from La Paz, Bolivia live fine, at 13,000 ft MSL, with "Pisco" brandy bottles at full flow.
xxx
With the OPEC barrel at $120... this is what we have come to. Sorry...
xxx
Happy contrails as usual...

Packs
 

Breecher, for all your indignation and accusations I note that you still have not specified the type of aircraft on which you operate. Would you care to enlighten us all with some FACTS?

Panel Operators - ESC's
 

fflyingdoguk. At the risk of getting some flak, the "panel operators" to which you refer are professional flight engineers or pilots qualified to act as flight engineers and just to set the record straight, they are not doing the job "in place of the ESC", rather the ESC now does, in part, what F/E's used to do. Not too sure how you ask a computer how to get around an unusual problem. Maybe you can't and that is why the MEL for modern aircraft is so much more restrictive than the MEL for those aircraft which carry a F/E.

Good post in support of F/E's "Old Fella".:D
However, I think "Fflyingdoguk" may be referring to FedEx, who I think have modified the cockpit lay-out of their DC10s, in order to make them similar to the MD11F and thereby be able to fly both types.
Having spent many years on the 747 Classic, it was quite a shock to convert to the -400 and not be whacked about the head by the F/E's check-list!;)

Facts didn't seem to be required for people to reach conclusions before, so why should they be now?

I think you are refering to the MD10,Dc10 with out the systems panel operator,given glass cockpit simular to the MD11,all i am saying is in reference to the panel operator quip is our MD11s spend alot less time on the ground than the old Dc10s(Read into that what you will).A flight engineer used to be just that a "flight engineer" an engineer who flew and also held a liscence(A&P) where as nowadays(with our company) they tend to be ex Capts F/Os that have to move to a back seat for age reasons etc. Our MEL for the DC10 and MD11 are very simular to the amount of restrictions that they apply,i would say if anything the MD11 MEL is slightly less restrictive.No offense to flight engineers but your time is up and the computers have all but taken over.

IMHO,
Perhaps we should try cycling ALL packs ON/OFF to save fuel instead of following the manufactures' recommendations!!
PS. When are you next going to get a bonus for your fuel savings by turning packs off?

I personally like to turn all packs ON/High Flow to make the air better for the crew and pax! and to extend my longevity.
HA56

On some of the old classic 747's, there were 1/2 pack switching with supplemental fans to increase airflow.

P.S. When you arrive somewhere and there's some problem that has you holding unexpectedly or you are short on fuel for whatever reason. That fuel you saved by not running a pack is suddenly your best friend.
As I said before, it's absolutely nothing to do with saving money for the company.

F/Es
 

fflyingdoguk, I am well aware of the situation re the demise of F/E's in the operation. Computers or not, my time was up. That does not mean F/E's can no longer contribute. point8six, I'm sure you benefited from the input of your friendly F/E, at least some of the time. Breecher, you obviously cannot advise the type you operate, if indeed you operate anything other than paper aeroplanes. Seems to me most of your posts come from a downward pointing orifice. Happy days.

You forgot to mention guys that on A321 there is a single pack dispatch limitation (found in MEL) which limits the cruise altitude to 31500'