Boeing 737NG alternate flap question

[mamad]

Hi guys

i have checked on boeing book for pilots and asked my instructor in vain

Question is : what is the electrical source of alternate flap on the Boeing 737NG

sorry if it has been covered i have not seen it


many thanks

[ImbracableCrunk]

AC Xfer Bus #2

[mamad]

Thanks

appreciate it

could you just provide your reference please

That would mean that in case you loose normal AC than you cannot extend your flaps ?

[NSEU]

That would mean that in case you lose normal AC then you cannot extend your flaps ?

Correct. DC systems are not powerful enough to drive TE Flaps. I can confirm from my airplane wiring schematics that Xfr Bus 2 supplies AC power to the TE flap alternate drive motor.

Note that 28V DC Bus 1 is required for _controlling_ the supply of Xfr Bus 2 AC power to the TE flap drive motor and for powering the hydraulic bypass valve. However, if you lose AC Xfr Bus 1, you should still get DC Bus 1 power for flap control if the Bus Transfer Switch is in AUTO.

[mamad]

Thank you NSEU

that is very clear

cheers

[de facto]

That would mean that in case you loose normal AC than you cannot extend your flaps ?

If you also had a loss of your hyfraulic B pressure for the flaps drive unit that is.