Help!-Flap sequencing on 747-400
 

Help... An Air Cadet asked me about 744 flap sequencing tonight and I hadn't a clue. Can any of you 744 jocks help?
What is the relationship between the leading edge droops (Are they Kruger flaps?) and the trailing edge flaps (slotted flaps?) for various flap lever selections eg flaps 1,5 10,20,30 etc. For example do the leading edge flaps come out at flaps 1 or 5 or what? along with the trailing edge flaps, or does one come out before the rest?
I don't know why hw wants to know but he's a good lad and I said I'd try to find out.

Not sure about the 747, but here is the answer for the 767, I can only imagine they'd be quite similar if not the same.

Selection of flaps 1 commands slats to move to mid-range position, flaps remain up. Selection of flaps 5, 15 or 20, commands slats to mid-range and flaps to selected position. The inboard ailerons droop in conjunction with flaps extension. Selection of flaps 25 or 30 commands slats to landing position and flaps to selected position.
Another interesting point is with flaps in 25 or 30 (in a -300) if you exceed the speed limit the flaps will automatically retract to position 20, and extend when speed is below limit.

The flap sequencing on the B744.
F0 all LEDs and TE flaps up.
F1 inbd & midspan LEDs ext, TE flaps up
F5 all LEDs ext, TE run to 5
F10, F20, F25 & F30 LEDs ext, TE flaps as selected.

BTW B744 has inbd, midspan and outbd LEDs, a total of 1 more (each wing) than B747. B747/744 LEDs have one ext position. The 3 inbd LEDs are Krueger flaps, the rest are slats. B747/744 does not have droops, all LEDs extend from under the leading edge through about 150 degrees and are bent to alter camber. B747/744 ailerons do not droop with flap ext.

The B747 hardware is very similar except for programming of LEDs & TE flaps run to posn 1. TE F1 gives a fair increase in area & bugger all increase in camber.
F1 3 LEDs inbd of each eng (ie 6 per wing) ext, TE flaps run out to 1
F5 all LEDs ext, TE flaps run to 5
F10, F20, F25 & F30 the same.

Hope that helps. :)

Thanks for that, now I've learnt something as well.