Originally Posted by
extricate
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In the article above, it talked about GE-90's flat rated temp (Tref) as ISA+15. In Dubai's case, it;s 30 deg. With an OAT of 39 degrees, it will exceed the Tref (as mentioned in the article), thus leading to a decrease in thrust in order to maintain the EGT limits.
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With an EGT margin of >9° C on both engines you will not exceed max EGT.