Boeing 747-400 Flap Drive problem

[airbusboeingdriver]

hi all,

please would you all be kind to share the following? thanks in advance.

during flap extension or retraction when you get a eicas 'flap drive", at what speed are we to fly aircraft? :confused:

then, says after a speed addition as per qrh, as soon as we inserted the new "higher" speed into the fms the indicated speed will be lower than the speed bug, do we adjust the indicated speed to match the speed bug or we leave it till we lower the next stage of flaps? :confused:

thanks

[Oasis]

If you were extending the flaps, you would add the vref addition, if you were retracting, you don't, because the flaps are already out and you can't retract them, and no buffer is needed.

dunno what you're asking on the second part of your post

cheers,

Oasis

[airbusboeingdriver]

thanks for reply. kind to share,

1) when we get a flap drive poblem during flap retraction say from 10 to 5, at what speed do we fly for this non-normal procedure?

2)the same question as above but this time during flap extention say from 5 to 10?

thanks

[boeing_bananas]

Hi.

I don't think there is any specific speed to aim for with this failure, just keep the speed below the max flap extension speed (red blocks on ASI), and above the speed bug for the flap setting that you have (eg. if flaps fail between 10 and 5, stay at a minimum of flap 5 speed).

One complication is that the autothrottle will try to keep the speed out of the amber speed range (1.2 or 1.3 Vs depending on the airline I believe). At heavy weights, there is not much (if any) gap between the top of the amber line and the beginning of the red blocks. You may therefore have to disconnect the autothrottle, and keep the speed in the top of the amber area (this will cause an EICAS >AIRSPEED LOW message). It may be a good idea to use HDG SEL with a max bank angle of say 15 degrees whilst you are dealing with the problem in this configuration.

Hope that helps or at least makes some sense!

BB.

[airbusboeingdriver]

thanks boeing banana.much appreciated.

cheers