Speed Brakes & Flaps - B747

[ROB-x38]

HI

As I understand it speed brakes and flaps are not to be used in conjuction on the B747 as per the AOM. Correct?

I also have info which says using the speedbrakes in flight does the following:
- spoiler panels # 1 and 2 no movement
- spoiler panels # 3 and 4 a maximum of 45 degrees
- spoiler panels # 5 and 6 a maximum of 20 degrees
Correct?

If this info is correct (beware i'm a low hour CPL with nothing in my logbook over 2000kg), how do you explain this photo?

http://www.airliners.net/open.file/491038/L/

Given that both the inboard and outboard ailerons are flush with the wing, and that spoilers for roll control utilise panels # 1 and 2 also, then isn't this a photo of speed brakes and flaps together?

Please clarify any info if wrong, otherwise :confused:

[Phil Squares]

Each airline has their own procedures for flaps and speedbrakes on the -400. At my airline, you can't select flaps and speedbrakes below 500'AGL. Above that there is no restriction at all.

I seem to remember in the classic, Boeing recommended not to select flaps and speedbrakes together. That was from the original -100s that were somewhat thrust limited at high gross weights.

Cheers!!:cool:

[ROB-x38]

Ah ok thanks Phil :ok: That clears it up.

Not using speedbrakes with flap out might only be a recommendation for the classics....

[18-Wheeler]

On the Classics *some* companies allow the use of speedbrakes with flaps, *some* allow it but frown upon it, the *smart* one do not allow it.
Using both vastly increases the chance of flap track cracks.

[Dan Winterland]

According to Boeing, on the 2/300 use of speed brake with flap is not recommended, my airline doesn't. On the 400, speedbrake can be used with flap up to flap 20, i.e. not with land flap. The airline used to fly 400s with allowed this.

Also, don't forget you will get some roll spoiler against flap in certain circumstances, but this wasn't the case in the photo.

[dartman]

We can use speed brake w/ flap, the limit being F-10, or F-20 depending on the tail #. Older -400's are resricted to F-10. It's still an airmanship issue as how much to use, as rather large sink rates can develop, whilist outside the GPWS envelope. If you forget the boards, when the thrust comes up you get an EICAC message and wailer.

d.