How to derate a JT8D-17 eng to a -15 eng

[airbirduk]

Hello,

I need advice please on how to derate a JT8D-17 engine to a -15 engine and more importantly the benefit (if any) of doing this.

Thanks.

[Reponator]

I believe all you have to do is trim the -17 to the -15 settings. The benefits would be that you can use a -17 in place of a -15 if you don't have one and possible some added fuel economy.

[Engineer_aus]

Don't forget the better life out of your engine to.