FLEX vs Target N1 on T/O performance data
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Join Date: May 2005
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FLEX vs Target N1 on T/O performance data
We've always used FLEX temp for setting T/O thrust with no info re the target N1.
Does anyboy's performance data include N1 along with the FLEX temp? Seems to me that if N1 is to be monitored during the roll, shouldn't there first be some kind of insight into whether the FADEC number displayed is realistic or not, otherwise what's the point?
Does anyboy's performance data include N1 along with the FLEX temp? Seems to me that if N1 is to be monitored during the roll, shouldn't there first be some kind of insight into whether the FADEC number displayed is realistic or not, otherwise what's the point?
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The problem is calculating the Flex N1, what you are looking at is a guage N1 and not the actual engine N1, because of the tempertature difference between ambient and flex, you cannot just look at the higher temperature and take the N1 value. We have therefore never expected crews to calculate the Flex/Assumed N1.
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Mutt
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Not the bus but the performance software for our 737s allways gives the target N1 for whatever combination of reduction we used (derate only, assumed temperature only, both combined). This can be crosschecked as the FMC gives the target N1 as well and of course later on can be checked on the engine instrumentation during the take off run.
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On the E195 manuals there are tables to corect the N1 to N1 flex, but I don't know if our crews use to calculate it or not.
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The box won't get it wrong so
We used to have the tables for the reduced N1 computation on our checklist and had to use it to crosscheck the FMC on the first flight of a day, but that was discontinued after a few years of operation and the tables were removed.