Retard From Flex/mct To Clb Thr Setting
 

Good Day All!
I Would Like To Ask A Question The Bus Drivers.
Is There Any Restriction (time Limit Or Altitude) On Setting The Levers Back To Clb After A T/o Using Flex!
Had To Left The Levers On Flex/mct Setting For A Little While After Thrust Reduction Altitude To Gain Fast Height To Initiate A Turn Due To Wx And High Terrain.
Thanks In Advance!

There shouldn't be a time limit. That's why they call it MAX CONTINUOUS. It will increase engine wear though. There is a 10min limit at TOGA thrust.

5 Min For Two Engine And 10 Min For Single Eng Ops

BAROREF, that is the TOGA limit. There is no limit in the FCOM for the FLX ... (or at least i couldn't find one)

until airbus changes it, there is no time limit to use flex thrust, although that flex thrust could be higher than the max continuous

Well no time restriction as such, though Autothrust will not be activated, and shall remain 'armed' till the thrust levers are brought back to the CLB detent (2 engine ops). This is because the CLB detent is the upper limit of the operational range of the A/T.

Safe skies

Disagree with some of the above... :ooh:

The time limit for Thrust settings between TOGA and MCT is 5/10min. Unless you have taken the trouble to determine whether the Flex Thrust you have set is at or below MCT, then IMHO the 5/10min limit applies.

If you need more Thrust in the Climb than Climb power, why not just set MCT - that's what it's there for..? As per FCOM 1, just cycle the TLs via TOGA or CL and back to MCT ;)

NoD

I have to agree on the above statements. Flex could be 1 deg below TOGA. I would say there is therefore a 10min limit at Flex before one would have to come back to Climb to activate A/T. Only then could you return the levers to the FLEX/MCT detent to achieve MCT. Only then will there be no time limit.

Nigel,

As much as I agree with you, if you look at the FCOM, there is no such limitation. So, there really isn't a limit, although there should be one.

Interesting one. The only time limit is as stated for takeoff and go-around thrust. I suspect the limit that would have to be observed in the described situation with flex thrust might be the MCT EGT limit unless otherwise stated. Just a quick one off the top of my head, however it would be nice it have a difinitive answer.

TAKE-OFF thrust is either Max (TOGA) or Flex; limit 5 mins all engines or 10 mins, one engine inop.
FLEX cannot be less than Climb thrust and often can be more.

will have to agree with Nigel that FLEX is limited to 5/10 mins.

The logical way to look at this is that FLEX is above MCT and MCT is the max continuous thrust meaning that is the maximum thrust you can run without any time limitation. So any thrust above it, you will be limited to the 5 or 10 mins restriction.

You are absolutely correct, thanks for reminding some of us.

Another ineteresting question arises with regards to the 5 min / 10 min limitation. If one were to go back to the CLB detent, and then return to the FLX/MCT or TOGA detent, would they technically be allowed to operate at that higher thrust gate for another 5 min / 10 min?

Can someone point to a place in the FCOM where it specifies a time limit for flex thrust? All I can find is Takeoff and go around, flex is not mentioned.

Jonty

Youve missed the point, mate.

T/O thrust IS Flex or TOGA Thrust. Not something else. The limits have been stated.

If you want MCT (no time limit), cycle the Thrust levers back to TOGA or CLB and then back to MCT.

FLEX/MCT is notFLEX and MCT.

You've got no limit for CLIMB, you've got no limit for MCT anything above these settings is considered a TOGA limit. (of course Climb may well equal MCT in some conditions)

FLEX is a variable feast that may give you a thrust above or below MCT - you can't normally tell, so wisdom and experience dictates that FLEX should be considered limited by the TOGA limits also.

Can't give you a FCOM reference but reading across from many other jet types this is likely to be true.

It's always good to be reminded how simple Airbus logic is. Thank God for SOP's

From my understanding, the 5 mins limit at take-off thrust is actually an EGT time limit.

For instance, the CFM56 engine (A340) has a EGT limit of 950 for up to 5 mins. For any lenght of time exceeding 5 mins, the max EGT allowed is 915. So whether it's Flex or Toga, one must reduce to MCT or less after 5 mins in order not to exceed 5 mins with an EGT over 915.

The AMM has a chart depicting the maintenance actions required in relation to the peak EGT and lenght of time when an exceedance as occured.

Do not cycle to TOGA to get out of any A/TH mode, under certain conditions, this will activate the G/A mode, not a big problem; but not ideal. Always cycle to CLB, then MCT.

RE