Is assumed temp working?

[DEHowie 269]

Gday guys,

Nice work on the Mad Dog.

My question relates to the use of assumed temp.

With TOGA selected the max EPR display is coming up with the correct max value say 1.94 for example.

If i then hit the flex button and dial in a temp of say 50 the max EPR indication above the EPR gauges is going blank and on selection of autothrottle on and take off thrust is set the EPR is running way beyone to around 2.2 or so.

On selecting the temp my understanding is it should display the corresponding EPR limit based off the dialed in temp and autothrust should limit take off thrust to this value.

It appears unless i am doing something wrong when you select the Flex option on the thrust rating limit panel that the EPR limit is being removed and at take off you are just getting maximum thrust not TOGA or the Flex ie assumed limit.

IE if TOGA is 1.94 then flex should be below that ie 1.85 at a guess.

I have been using the ready to fly option and have not tested this from cold and dark.

Ideas?

Regrds

Darren

[thibodba57 462]

18 minutes ago, DEHowie said:

 

If i then hit the flex button and dial in a temp of say 50 the max EPR indication above the EPR gauges is going blank and on selection of autothrottle on and take off thrust is set the EPR is running way beyone to around 2.2 or so.

Goes blank or is covered in dashes?  Any Eng-Anti-ice on?  Under the TRC is the "No Mode" illuminated?  You're overboosting the engines as the autothrottle doesn't have overboost protection, it goes to the EPR Limit point which you pointed out does not exist.  Review Procedure Guide Chap 2 Page 21.

Edited February 25, 2018 by thibodba57

[DEHowie 269]

It has dashes.

My understanding is that with a flex temp dialled in the max EPR for that temperature should be displayed and if autothrust is used for take off the max thrust should be limited to that EPR value.

At the moment with dashes displayed there is no limit and yes the engines overboost.

Will check your refs thanks...

[thibodba57 462]

No engine anti-ice on?

[DEHowie 269]

1 minute ago, thibodba57 said:

No engine anti-ice on?

no engine anti ice..

[DEHowie 269]

Might be the ART checking now...

 

[DEHowie 269]

Yep it was the ART setting that disables the flex..THANKS!

[thibodba57 462]

ART is required to be off, but I'm pretty sure you can set the temp with ART in the on position.  I guess I just get in a flow of TO FLEX>ART>Set temp when I'm doing it.  Glad you narrowed it down.