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Printed From: ATR Discussion Forums
Category: ATR Discussion Forums
Forum Name: Pilot to Pilot - Flying the ATR
Forum Description: Discuss proper flying procedures and systems management.
Printed Date: October-17-2021 at 3:11pm
Software Version: Web Wiz Forums 12.04 -

Topic: Uptrim?
Posted By: rici1
Subject: Uptrim?
Date Posted: November-03-2004 at 10:32am

can anyone tell me what uptrim is? something to do with the ATPCS...


Also does anyone know how to stop the VC becoming dark as you turn about the sun? I have treid deselecting lens flare and sun glare, but to no effect! thanks


Posted By: Todd Nicholson
Date Posted: November-03-2004 at 11:05am
As far as the VC, this is an FS issue and happens in all VCs.  You can turn on dome lighting and it will help with this.


Posted By: asfrag
Date Posted: November-03-2004 at 11:40am

The uptrim is a part of the ATPCS system, the other one is the Auto feather.

First of all, to have the ATPCS active, PWR MGT must be in the TO position.

Then, for example: when after take off one of your engine fails and stops, the ATPCS sequence will start, providing you with Auto feather (the failed engine prop's will pass automaticaly to Feather position) and UPTRIM on the running engine.

Actually during normal take off, you can notice that, with PL in the notch, you have 90% indicated on the torque, that's normal. When the UP TRIM starts the torque increases immediatly to 100%. It provides the maximum power to the alive engine.

That's why in case of engine failure after take off you MUST check that the Up trim AND the Auto feather system work properly.. otherwise you have to move the PL manualy to 100% and the failed prop CL's to FEATHER or the aircraft will be very hard to control, believe me

Posted By: eagledriver
Date Posted: November-08-2004 at 10:06am

asfrag's explanation is correct, although incomplete.

ATPCS (Automatic Takeoff Power Control System) does the following things:

-provides uptrim to the operating engine up to 10% torque and 1.3% NH, NOT TO EXCEED 100% torque (the objective torque setting for takeoff in the ATR-42 was 92%, hence the "NOT TO EXCEED 100%" clause.

-provides autofeathering of the failed engine following a 2.15 second delay (this allows the flight crew time to abort the takeoff, pulling the power back and cancelling the ATPCS autofeathering to give the crew any available reverse that might still be available to the culprit engine).

-provides autofeathering of the failed engine on approach (uptrim NOT available since you are manually setting go around power).

Hope this helps


ATP, ATR-42/72-212/72-212A

American Eagle Airlines


Posted By: asfrag
Date Posted: November-08-2004 at 12:30pm

the objective torque is 92% for 42.300 but 90% on 42.500.

The 42.300 doesn't have any notch.. everything is done manualy..

Posted By: eagledriver
Date Posted: November-09-2004 at 10:03am
I don't miss flying the 42s!!!


Posted By: Lavish
Date Posted: January-15-2021 at 2:16pm
ATPCS is not armed once PWR MGT out of T/O so can we put the ATPCS switch to off and put it back ON again after selecting Landing gear down cos after climb procedure to before go around we will not have ATPCS. Its not standard but just to clear the doubt or is there anything the ATPCS swith in ON position does during flight ??
Thank you

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