I have a Boeing mentality and was therefore surprised when Airbus instructors advised us that there isn’t a time limit for FLX, they have interpreted the regulation that Takeoff and Go-Around thrust must have a time limit. FLX thrust isn’t written in the regulation, therefore it doesn’t apply and isn’t listed as a restriction in the FCOM!

And yet, if you use the Airbus LPC to calculate FLX, the performance is based upon completing the takeoff within 10 minutes!

So it’s as clear as mud!

Mutt

IMHO, it doesn't matter if we're talking about Flex, Toga, derated thrust, go-around, etc. The limitations as per the FCOM are time limits relating to a EGT limit and those limits apply in all cases. The engine doesn't know what phase of flight it is in; it only knows what temperature it's being subjected to.

So a Flex setting must respect those limits, as all thrust settings must for that matter. If a HP degradation results in CLB thrust exceeding the EGT and time limit, you'll have to reduce the thrust even though there's no actual time limit on having the levers in the CLB detent.

The levers' position is only of concern to make sure the correct thrust setting is selected, so as to not exceed a EGT limit, assuming all is working correctly.