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qwsa
7th Oct 2012, 16:59
Hi all,
Is there any time limit of using FLEX power instead of TOGA on A320 for take off?
TOGA-5 min or 10min in case of engine out, but what about FLEX?

fantom
7th Oct 2012, 19:37
The limit on TOGA is noise related only. It is all about noise abatments and all that...

Completely wrong. The time limit on TOGA is an engine limitation.

Stuck_in_an_ATR
7th Oct 2012, 20:57
AFAIK, there's the same time limit on FLEX and TOGA

NOLAND3
7th Oct 2012, 21:15
True, and to confuse things more FLEX & MCT share the same gate.

safelife
7th Oct 2012, 21:20
Flex is time limited in the same way as TOGA thrust. However, technically it can be more or less than MCT - if you knew it was less, you could keep it forever. But the pilot normally can't judge the relationship of MCT and FLEX.

Squawk-7600
7th Oct 2012, 22:09
Yes that's quite true.

The time limit on takeoff thrust is due to engine life, hence why it's 10 minutes instead of 5 for EO ops. At high EGTs engine life deteriorates non-linearly ie an increase of 5 degrees may reduce engine life 5 hours, but increase 5 degrees more and the life may reduce 500 hours (fictitious numbers by the way, merely to illustrate the point). The converse is also true, so at a high FLEX temperature the time limit would be greatly increased. However to actually calculate that on the line would be too complicated, and to be perfectly honest quite unnecessary. Good question though! :ok:

reubenjosephdsouza
8th Oct 2012, 07:07
Toga limit for both eng. take off is 5 min n with SE OPS it's 10 min, now also with this u have ur takeoff temp limit for both eggs given, eg.

CFM ENG MAX EGT FOR TAKE OFF IS 950 , but using MCT IS 915 , now the 10 min toga power on SE ops and 5 min on both eng take off does apply but also bearing in mind the max eng EGT ie 950, but when u use MCT ITS NOT TIME LIMITED But EGT LIMITED SUNCE U KEEP MONITORING THE EGT SO AS TO NOT GO ABOVE EGT LIMIT OF 915 ,hence toga and flex take off have their temp and time limitations for both eng ops and SE OPS,

TOGA TAKEOFF AND FLEX TO ARE NOT THE SAME, TOGA TAKE OFF WILL REDUCE LONG TERM ENG LIFE DRASTICALLY, WHERE AS FLEX TO WILL INCREASE ENG LIFE , AND ALSO REDUCE ENG MAINTAINANCE COST.

just like mentioned earlier by SQUAK7600, the rate of damage is non linear hence its becomes difficult to actually check up how much damage has occurred over a give period of eng hours.

MOSTLY FLEX TAKE OFF IS USED FOR EVERYDAY OPS UNLESS IT'S NOT POSSIBLE TO EXECUTE A FLEX TAKEOFF DUE TO PERFORMANCE LIMITATIONS FOR A GIVEN FLIGHT, THUS LEADING TO A TOGA TAKEOFF. in my company we Mohave to make a pilot report of toga take off has been used instead of a flex takeoff, post flight in the post Flt report form, so that mx crew have a record of it , just to keep monitor eng life.

Well hope this give u a little better idea of flex and toga not being the same,

mohamedarab
17th Oct 2012, 23:30
this informations from
aircraft performance (Flight Operations Support & Line Assistance) airbus

- The TakeOff (TOGA) thrust represents the maximum thrust available for
takeoff. It is certified for a maximum time of 10 minutes, in case of engine failure at
takeoff, or 5 minutes with all engines operative.
- The Go Around (TOGA) thrust is the maximum thrust available for goaround.
The time limits are the same as for takeoff.
- The Maximum Continuous Thrust (MCT) is the maximum thrust that can be
used unlimitedly in flight. It must be selected in case of engine failure, when TOGA
thrust is no longer allowed due to time limitation.
- The Climb (CL) thrust represents the maximum thrust available during the
climb phase to the cruise flight level. Note that the maximum climb thrust is greater
than the maximum cruise thrust available during the cruise phaseThe aircraft actual takeoff weight is often lower than the maximum
regulatory takeoff weight. Therefore, in certain cases, it is possible to takeoff at a
thrust less than the Maximum Takeoff Thrust. It is advantageous to adjust the thrust
to the actual weight, as it increases engine life and reliability, while reducing
maintenance and operating costs.