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747-400 EEC alternate mode

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747-400 EEC alternate mode

Old 13th Dec 2000, 13:18
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Question 747-400 EEC alternate mode

I fly 747-400 with PW4056 engines.
In case of alternate mode EEC, the performance manual of the a/c I have flown before(A 300-600 with PW4158) provided the N1 nbr's for each phase of flight.
Boeing QRH(747-400) provides EPR for T/O and go-around but there is no ref for climb and MCT thrust.
Does this mean that pilot can set the thrust for climb or MCT by the ref EPR indication of the primary EICAS display?
Does anybody have any idea?
Old 16th Dec 2000, 04:28
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"Does this mean that pilot can set the thrust for climb or MCT by the ref EPR indication of the primary EICAS display?"

Not sure about the EEC's on P&W's, but on the Rollers, the EEC's revert to Altn N1 control when EPR info is not reliable/available. In such circumstances, as an engineer, I would not recommend using the EPR display to set your throttles in any stage of flight(in ALTN mode).

Old 16th Dec 2000, 12:05
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From our mel for 744 with RR eng

1.Select all eec mode switches to Alternate,
Thrust setting at T/O is accomplished by manually setting thrust on engines with EPR
2.auto throttle is not avail in ALT mode
Limitations performance adj and restrictions-
Use target thrust setting bugs displayed when all 4 eec are in alt thrust mode. Note that EPR targets in alt mode will be different from the nml mode targets and will approximate 10% derate (TO1). DO NOT select derate.
Use of improved climb performance is prohibited.

There are many restrictions for weights/performance etc.
Therefore You will still get EPR indications and thrust will be set to bugs. But as QAVION says the eng is now under N! control/limitations.


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