Colleagues have told me that they prefer not to derate because 'in windshear and go-around you will not get maximum thrust anymore'
Wrong.
First of all,if conditions of Windshear exist,Boeing does not allow to derate,so thats easy no?Your colleagues should know that.
A derate as mentioned is a LIMIT IF you have an engine failure.As your v2 selected speed takes in account the engine rating for VMCA.
If you used derate and you do get into a windshear, you are ALLOWED to increase thrust to MAX on BOTH engines.
If you chose to derate, its the same as changing your engine...your friends fly with 24 K engines also no>?well i guess they are not worried then,are they?
In a go around,you will have full thrust available.(26K or 24K depending of your engine rating(FMC) with the AT ON and MAX thrust 27.3 if you firewall them.
There has been reports of the AT not giving required thrust during a go around after an assume temp was performed.
it was due to the fact the aircraft had not reached its washout altitude.
Therefore if you use ass temp and return to land for some reason ,a go around should be with AT OFF and correct GA N1 briefed from QRH.
The EEC will monitor the fuel via the HMU to avoid N2 overspeed.
ASSUME TEMP is lying to the FMC to reduce your thrust, your perf for a go and reject are inherently safe as your calculated speeds are for the hotter temp.
if you reject,your TAS will be less as real temp is colder.
if you go ,your perf will be better (higher climb gradient) as the OAT is colder that what you set in the FMC.
If you derate and ASSume, you can get rid of the assume temp by clicking TOGA after 800 ft when the AT is not in HOLD mode anymore,or by disengaging the AT before or after 800 ft and setting the required thrust manually.
Your engine may have a plug to 26 K so firewall will not achieve 27.3k, you will have a placard in the flight deck in that case.(and i believe on the engine name plate,in the config space,the engine version).
Am I right in my understanding that this will not limit you on subsequent go-arounds or during windshear recovery (but instead the maximum rated thrust set by the ID-plug)?
you are correct.
I think your colleagues (captains?) should dust off their books such as the basic FCTM for a start....
Never too late i guess...