Monty43

How to calculate the FLEX TEMP? (Tutorial)

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Thanks for the tutorial!

However, where can one acquire the performance tables illustrated in your post? The TFDi does not seem to include these.

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On 29/8/2017 at 10:06 AM, raunzos said:

Thanks for the tutorial!

However, where can one acquire the performance tables illustrated in your post? The TFDi does not seem to include these.

Hello raunzos,

The table are from Flight Crew Operation Manual (Performance chapter) is real documentation. You can get here http://www.mycockpit.org/forums/downloads.php?do=cat&id=6&page=3

Regards.

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I've been using and enjoying that flex calculator since early this year - unfortunately, I now see this message on the 717 one:

This webpage will be terminated shortly. If you need the data in excel format, contact me on the email address at bottom of the page!

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the website is not accepting new registrations-a recaptcha issue.Can anyone send me all the pertinant tables as I am unable to access them/I notice runway length stops at 3600 meters-if you have a much longer runway such as KDFW,do the actual tables reflect longer lengths or do you use the 3600 figure for anything over that?thanks

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On 6/25/2018 at 4:06 AM, hbrammer said:

the website is not accepting new registrations-a recaptcha issue.Can anyone send me all the pertinant tables as I am unable to access them/I notice runway length stops at 3600 meters-if you have a much longer runway such as KDFW,do the actual tables reflect longer lengths or do you use the 3600 figure for anything over that?thanks

Manufacturer's manual has until 3600 meters only because this manuals are generic and the manufacturer considers this minimum distance for maximum reduced thrust and weight of the aircraft, in real life each operator of aircraft has its own tables for each airport that they operate. But if you have 4500 meters of runway you can do the calculations with 3600 meters, is valid.

Regards.

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Is it possible to combine a flex temp with an engine derate? Or is it to choose one or the other? You explained the flex temp very well - can you also elaborate on the use of derate?

Thanks,

Chris

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Posted (edited)
On 1/2/2019 at 7:47 PM, Chris Smith said:

Is it possible to combine a flex temp with an engine derate? Or is it to choose one or the other? You explained the flex temp very well - can you also elaborate on the use of derate?

Thanks,

Chris

Hello Chris,

Sorry for the delay, I worked out of my country for a time. I am going to try explain below:

The law dictates that takeoff thrust may only be reduced by a maximum of 25% from nominal maximum thrust. Therefore, if you thrust limit the engine by 10% or 20% upon 100% (nominal thrust) you obtain 90% or 80% as nominal thrust, you can then apply a further 25% reduction upon this thrust limit with an assumed temperature/FLEX TEMP, in others word upon 90% or 80% you can reduce others 25% in total will be a maximun of -35% or -45% thrust reduction. It is a small trap to comply with the law and to extend the life of the engines even more.

How to calculate? simple the aircraft operator chooses the thrust limit in according with the same tables above but calculated for a thrust limit of 10% or 20%. I don't have this tables, I have only the generics and it's 100% thrust.

Regards.

 

Edited by Monty43

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