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!:)