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hedgehog-in-fog
18th Oct 2006, 16:43
Hi

Got a question about 320’s new RTOW charts. At the bottom of these charts there’s a box with Tref (OAT) and Tmax (OAT).
Tref is Tref but what is Tmax? Is that the MAX permissible outside temperature to fly from this field or T max flex? According to the text description of Tflex calculation with weight entry we have to check actual Tflex with T max flex. In the old charts it was indicated as T max flex in the upper part. In the new there’s no one. Do we have to calculate it ourselves Tmaxflex=Tisa+44 ?
From the other side in the diagram 2.02.20.p8 showing the steps of calculation T flex there’s no point, indicating that we have to check T flex actual with T max flex. IMHO it indicates that Tflex shown in the new RTOW will never go above T max flex and that Tmax, shown at the bottom of the chart is the max outside temperature to fly from this field.
Am I right? Discussions have been going on, pushing me deeper in the fog.
Cheers!

bizness99seat
8th Mar 2008, 13:50
TMAX is the maximum OAT certified for take-off, ensuring that the MCT limit is not exceeded. The value reduces as pressure altitude increases. (ie is not aerodrome/field specific!)

TMAXFLEX is the maximum usable flex temperature, when actual thrust is 75% of the rated take-off thrust.

It would be good if TMAXFLEX were indicated on the chart in some way but I think you can easily calculate it can't you? - it is ISA + 40°C.

mutt
8th Mar 2008, 17:22
ensuring that the MCT limit is not exceededMCT??? Is this an airbus thing?


Mutt

PA38-Pilot
8th Mar 2008, 23:04
MCT??? Is this an airbus thing?

MCT stands for "Maximum Continuous thrust", and... well, you could consider it "an airbus thing" if you want :}

mutt
9th Mar 2008, 03:36
"Maximum Continuous thrust"TMAX is the maximum OAT certified for take-off, ensuring that the MCT limit is not exceededWhat has MCT got to do with the environmental envelope or the extended environmental envelope? At what stage during a takeoff is MCT selected?

Mutt

vagabond 47
9th Mar 2008, 04:38
At the end of the 3rd segment after engine failure with flaps retracted, or after max t/o thrust limit time;usually engine manufacturers limit of 5 or 10 mins.