Tech question derated vs flat rated engines difference
Thread Starter
Joined: Jul 2010
Posts: 57
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From: n/a
Tech question derated vs flat rated engines difference
Hi all
I am sorry if this question has been discussed already but i couldnt find it.
I d like to know if someone can explain me the difference, if any, between a flat rated engine and a derated engine.
I found this 2 questions in an interview questions database but i cant really get the difference between the two.
Thanks in advance
I am sorry if this question has been discussed already but i couldnt find it.
I d like to know if someone can explain me the difference, if any, between a flat rated engine and a derated engine.
I found this 2 questions in an interview questions database but i cant really get the difference between the two.
Thanks in advance
Joined: Apr 2010
Posts: 1,319
Likes: 100
From: IRS NAV ONLY
A flat-rated engine is an engine, which produces the same amount of thrust regardless of temperature from a certain temperature point (around ISA+15 for most engines).
A derated engine is an engine, that has been modified (this modification can be very simple - depends on engine/airframe) to always produce less thrust than what it was designed for. Reasons for this may be better (smaller) noise footprint, reduced maintenance cost, increased EGT margin, reduced VMCG/A, ... On some aircraft you have an option of a fixed (permanent) derate, which requires maintenance action and a "semi-fixed" derate, which can be selected by flight crew to conform the operational needs.
A derated engine is an engine, that has been modified (this modification can be very simple - depends on engine/airframe) to always produce less thrust than what it was designed for. Reasons for this may be better (smaller) noise footprint, reduced maintenance cost, increased EGT margin, reduced VMCG/A, ... On some aircraft you have an option of a fixed (permanent) derate, which requires maintenance action and a "semi-fixed" derate, which can be selected by flight crew to conform the operational needs.
