Flaps usages

[Tom Stian]

Hello

I was wondring.

If im right, the normal usage of flaps is 1, 5, 15, 30 and 40. (I may be very wrong)

Each flaps have its own minimum/schedule maneuvering speeds.

Below 53 tons the Boeing manual says (schedule):
Up: 210kts
1: 190
5: 180
10: 170
15: 150
25: 140

The IXEG Checklist says (minimum):
Up: 210kts
1: 190
5: 170
10: 160
15: 150
25: 140

What I dont understand here is that the Boeing manual says that the flap maneuver speed provide approximately 15-20 knots above the minimum maneuvering speed for each flap setting. But the flaps settings for schedule and minimum are the same except flap 5 and 10.

 

Back to the normal flap usage, how strict is it to follow that? or is it strict at all?:
If I follow the schedule, can I use flap 10 if ATC tells me or a procedure requiers me to maintain 170 kts, or should I then go flap 15?

 

What is best practice?

[Tchou]

From what i've read flaps 10 setting is only for single engine procedures, and maybe flaps 25 also, I don't recall.  

[Litjan]

There has been a time (after the Pittsburgh crash) when all maneuvering speeds were increased by 10 kts (crossover issue). So in case the rudder freaks out, you can still counteract that with the ailerons. But that was uniformly for all speeds (i.e. Up = 220kts).

So I am not sure where the discrepancy comes from.

You can certainly use flaps 10 to fly 160 (we do it in London, where the controllers have a hissy-fit if you don´t fly EXACTLY 160 to 4 DME...).

You could also use flaps 15 to fly 150, but the gear warning will freak out if you pull out the power...

Jan

[Tom Stian]

Thanks for your answer

And yea, I know what you meaning, I also often get 160kts until 4DME (on vatsim  ) at the London airports. So it would be nice to use flaps 10 for that.

Not sure what the limits for pitching/AOA are, but last time I used flap 10/160kts at level flight I think the pitch was a bit high. I dont remember exact, but maybe 7-8 degrees or so. And I have no idea how heavy I was either. But will do some reading about it. Thanks again.

Edited June 27, 2016 by Tom Stian

[Litjan]

13 hours ago, Tom Stian said:

I dont remember exact, but maybe 7-8 degrees or so.

Sounds about right.

Jan