Originally Posted by
763 jock
Used to fly the same type which had both 5 and 10 minutes on the fleet. Some frames were 5 minutes, others 10. As the engines all got swapped around, it was all pretty much nonsense and was driven by the tail number rather than anything to do with the engines.
10 minute Takeoff is an 'extra cost' option from the engine manufacturer - mainly because it has warrantee implications as 10 minutes at Max Takeoff takes a lot of life out of the engine. You are correct that the engine doesn't change (same thing is true for most ratings changes - the engine company charges for because higher ratings reduce engine life and have warrantee implications. Also because higher ratings are 'value added' to the customer so they expect to get paid for that extra value (ditto for 10 minute takeoff).
The airframer also has to make some changes to EICAS (or the equivalent) as the takeoff EGT (and sometimes rotor speed limits) are higher for TO than Max Con, so the exceedance logic needs to reflect that.