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JSACKS

744 (FS9) - N1 t/o limit with manual control & FMC

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If you set up the FMC for takeoff and set a reduced thrust using TO1 or 2 or Assumed temp, for e.g, and then you decide to takeoff completely manually without the assistance of the TOGA function, should you be able to exceed the calculated N1 setting displayed in the FMC and firewall the thrust levers to the max or would the FMC still restrict you to the calculated N1 only? I ask because I just did a test of fully manual takeoff with the thrust levers and found that I was able to exceed the FMC calculated N1 and go to max N1 which was surprising to me. I am wondering if this is the way the thrust delivery is supposed to work. Appreciate any replies, thanks!Jonathan

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The computers in Boeings rarely (if ever) override the pilot. In this case, if the throttles are firewalled the engines will give you everything they've got... it might mean a trip to maintenance but it might also avert an uglier situation.

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I tried the same thing with the Level-D 767 and found the same result: the engines gave me everything they got.However, my PSS 777 does not do this: it only gives me what the FMC specifies for the takeoff thrust level. I wonder if this represents a change of design as BOEING headed into the semi fly by wire world?Interesting.Jonathan

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"However, my PSS 777 does not do this: it only gives me what the FMC specifies for the takeoff thrust level. I wonder if this represents a change of design as BOEING headed into the semi fly by wire world?"Sorry, but no changes... The PSS 777 must be wrong. Firewalling the throttles should give you max available thrust (for the atmospheric conditions), and won't stop at the derated thrust. You shouldn't get any n1 exceedances(sp?), but you might get EGT exceedances if you leave the thrust too high for too long.The 744 is fly by wire throttle. Later versions of the 767 are fly by wire throttle also. However, even on earlier series 767's with non-FADEC engines, you will get full available thrust.Cheers.Q> Ян

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Thanks, Q; I couldn't answer with certainty. I've read for years in places like AW&ST and TWSJ that a basic philosophical difference between Boeing and EADS is in who they trust. Boeing knows that the pilot-in-command has the ultimate responsibility, and they give him the authority. EADS (Airbus) doesn't trust the pilot to always make the best decision, so they give a computer the ultimate authority. I believe either side could be effectively argued, but my preference is to give the guy with responsibility all the authority they need to do the job.

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Thank you, gentlemen, this makes it clear. I feel better educated now. Appreciated!Jonathan

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