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Old 1st Mar 2017, 08:42
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jgoggi
 
Join Date: Dec 2007
Location: Rome-Italy
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HOLD mode at takeoff completely manual?

Hi, a question about the 747-400 with GE engines. After the TOGA switch is pressed at takeoff, the thrust goes into THR REF mode and sticks to the green reference N1. At 65 knots the speed mode changes into HOLD and the A/T disconnects until 400 ft. In this interval, if TAT, speed and altitude change, I suppose the green reference N1 will slightly change (say it goes from 98.2 to 98.3). Will there be a consequent increase in the actual thrust from 98.2 to 98.3, commanded by the EEC, or is the thrust completely manual and disconnected from any sort of 'protection' by the EEC, so that if the pilot doesn't touch the thrust levers the thrust does not change at all?
Thanks.
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