737NUT Posted May 31, 2017 Report Posted May 31, 2017 (edited) I am having some N1 issues, When taking off I am only getting 82% N1 when i press TOGA. I tried manually adjusting to 91% on the N1 gauge, no joy. Does the same thing when using the FMC, only gives 82-83% when FMC says we should be at 90 to 91. So my question is, Is the N1 control logic implemented to where if say i'm in N1 hold, I can manually what N1 I want the autothrottle to maintain? Also when FMC is controlling autothrottle via VNAV, why doe sthe commanded N1 cursor not move? Thanks Rob Edited June 1, 2017 by Morten
Morten Posted May 31, 2017 Report Posted May 31, 2017 Ok, we don't support that yet as you know, but haven't heard of that problem before. Maybe you altered something in planemaker by accident? Also check that you throttle hardware axis is calibrated full length in the settings.
737NUT Posted May 31, 2017 Author Report Posted May 31, 2017 It's not hardware related as I can manually push levers forward and get 100% rpm. I'll video and post tonight. Basically if I throttle up to 40%, stabilize, then hit TOGA, it only commands 82% N1. After T/O and above 1500ft, I engage either LVL Change or VNAV depending on flight, and immediately throttles move forward to 90- 91% as it should. Rob
Morten Posted May 31, 2017 Report Posted May 31, 2017 Do you use some engine derate or assumed temperature (flex) on the FMC? What is the true outside temperature?
737NUT Posted May 31, 2017 Author Report Posted May 31, 2017 No derate, Temps 15 to 23C Most of the time I don't even touch the FMC. I usually fly /A.
Litjan Posted May 31, 2017 Report Posted May 31, 2017 Weird - are you sure that you are not hitting the 84kts IAS shutoff-value for autothrottle adjustments? If you do a rolling takeoff in a light airplane with strong winds its easy to reach this value of IAS, and the autothrottle will just die right there (as signified by the THR HOLD message). Jan
737NUT Posted June 1, 2017 Author Report Posted June 1, 2017 (edited) Ok, went to make the video tonight and then it hit me what I was doing wrong. If you want to manually set N1 you have to pull out the adj knob on the N1 gauge and set desired N1 and leave knob out. It worked perfect! To use FMC desired N1, Adj. knob must be pushed in and parameters entered into FMC via the CDU. Sorry for the confusion. RTRFM !! lol Rob Edited June 1, 2017 by 737NUT 1
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