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jet_breeze
13th Mar 2003, 22:07
Does any A320 pilots know what the significance of the packs on a A320 at takeoff being off ?

AKAAB
13th Mar 2003, 22:38
Probably selected off to increase performance on shorter runways. As long as you haven't just been deiced, it's probably better to leave the APU on with APU Bleed running the packs.

If using Packs OFF for takeoff, just remember to select the first one on at first power reduction.

In Long Beach (KLGB) we sometimes use the packs off or packs on APU Bleed for takeoff to keep us from having to use TOGA Power (Full Power). Flex power takeoffs (reduced thrust) ultimately save wear on the engines. Any reduction of EGT helps extend engine life.

Cheers,

AKAAB

jet_breeze
13th Mar 2003, 22:59
Thanks for the reply , yes i assumed it was to do with the engines as the packs were off during a TOGA powered takeoff on a video i watched at first i thought it was to do with pressure but its not.
thanks again

TE RANGI
15th Mar 2003, 10:23
On the A320 (IAE engines) you have to reduce your performance limited TOW by 1900 kilos if you take off with packs on.

Packs off T/O or APU feeding the packs would have the same effect.

Rgrds

longarm
18th Mar 2003, 10:33
We have A321's with IAE engines. We carry out all take off's with packs off in order to decrease engine wear, this is regardless of conditions and even with a maximum flex. Our A320's are CFM powered and we use packs off only when needed for performance.

Rabbit
19th Mar 2003, 09:35
We use to use packs off for take-off on both A320's and A340's, reason is simple - engine life. However, in recent years we have been using packs on APU for all take-off's. Same result but better for the pax.

Have a nice day

jet_breeze
19th Mar 2003, 15:48
Obviously being no A320 pilot myself i won't know a lot but i do know that the packs automatically turn off for engine start and the bleed air ( i think ) makes the turbines turn. Now during takeoff the engines will be under a lot of pressure basically its like your car if you need that extra power open a window and turn the air conditioning off.

foxtrot
20th Mar 2003, 07:41
hi,
leaving packs on engines for t/o causes you to lose 1900 kgs or 4 degrees on the flex depending on the system you are using.
therefore selecting packs off or on the APU at high weights will increase the flex temp, reducing thermal and mechanical stresses in the engines.
The IAE 2527 A5 engine is flat rated up to ISA +31 at sealevel,therefore it requires the same EPR setting at all temp below Tref. The engine is limited for mechanical reasons in this reason. When above Tref the engine is limited by the heat generated and the EPR is reduced so as not to overheat the engine. The main reason for engine wear is excessive heat and the best way of saving the engine is to reduce the heat. This is done by reducing EPR using a Flexible take off.
bye guys

jet_breeze
20th Mar 2003, 20:38
Thanks for the answers