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744pilot

another one

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Now that were talking about the manual. I was reading the EICAS/ENGINE section and do I understand it correctly that if you're (for example) in climb and lose one EEC the thrust setting will change even if you have static climb rate and now throttle changing.It's a part that I not understand fully.Thanks,

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I forgot to add the question...my question is: Is it true that thrust settings change.PS. That "now" in the last sentence should be "no"

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Guest Dutch Commando

11 - 24 AIRCRAFT SYSTEMS2nd column below the picture."The alternate mode provides equal or greater thrust than the normal mode for the same throttle position. Thrust does not change when the EEC transfers control automatically from the normal to alternate mode. Thrust increases when control is selected manually."So simply said, if the EEC automatically switches to Alternate the thrust will NOT change before you change the throttle position. If you manually change it to alternate mode the thrust will increase (most likely not much but some.)

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Thanks David.But I still not understand how that happends?

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Guest rellehenk

Hi Ramon,Quote from 744 manual:Alternate modeThe Alternate mode is a back up mode.If the actual environmental data input is lost, the EEC cannot control the engine in the Normal mode andautomatically transfers to the Alternate mode. This transfer is called the soft reversion. Last knownenvironmental data is used for N1 calculation. Initially thrust does not change during a soft reversion.The alternate mode can also be selected manually using the EEC P/Bs. This manual transfer is calledhard reversionary mode. Worst case data is now used for N1 calculation. Consequently thrust increasesduring a hard reversion. At high thrustsetting, trustlevers should be moved to the mid position prior tomanually selecting the alternate mode to prevent maximum N1 exceedance.If any EEC transfers to the Alternate mode, the A/T automatically disconnects. The A/T can bere-engaged after all EECs are manually transferred to Alternate.Maximum N1 is reached at a thrust lever position less than full forward. Thrust limiting at maximum N1 isnot provided.When actual data is lost, thrust levers must be adjusted periodically to maintain desired reference N1when the A/T is not engaged.

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Ok thanks Floris. I'll think I now know how the EECs work.

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