mct on AIRBUS

[barit1]

From an old engineman's perspective -

Max CLB is a OEM warranty rating, and NOT a certification point. At some conditions, notably TOC, CLB and MCT may in fact converge.

But MCT is not a safety issue at all; It's a matter of warranty coverage by the OEM. If your FDR shows untoward MCT usage, your airline may have trouble collecting on parts life warranty.

For years, I did repeated ground testing of big fans in which we acceled slowly to MCT, held 5 minutes for thermal stabilization, then ran 30 min. or more at various TO ratings before retarding below MCT. I can show you over 100 hrs. experience doing this testing on one engine. There was never a mechanical reliability issue, although some performance falloff naturally occurred.

So it's strictly the Captain's choice; you trade off increased deterioration (which means more fuel burned over the on-wing engine life) vs making a FL "gate". Talk it over with your beancounters, make the decision that's right for your airline, but don't let safety worry you.