Hoping someone can shed some light/info on a few questions I have about the Boeing 737 specifically in regards to the Flaps system and also the reason for Flap 15 Landings for a number of Non Normal situations.
In regards to the leading Edge devices, is it a coincidence that the limit speed for the full extension of the LE Devices (230 Knots) is the same as the alternate flap extension speed of the TE Devices?
Why is it that if you only have one LE Device out (in a non-normal for instance) your limit speed is 300 Knots/.65 Mach but any more than one it reverts to the 230 Knots.
The other questions relates to the reason why the selection of Flap 15 is dictated so much in a number of non normal situations.
For instance I can understand (or think I do!) why Flap 15 would be best suited for landing with:
- Loss of SYS B, it would take too long in the case of a Go-around to retract the flaps electronically hence degrading your go around performance
- Jammed stabiliser, you possibly would not have enough elevator authority to round out/flare with greater flap setting
What I cannot seem to understand or figure out, is the most obvious reason why it is scripted to Land Flap 15 in the following non normal situations.
-LE FLAPS TRANSIT light stays illuminated after the flaps are up.
-Jammed or Restricted Flight Controls
-Trailing Edge Flap Disagree Cx List with the option of selection: Indicated flap position is 15 or greater and less than 30: Land using existing flaps.
In relation to these why Flap 15, particular on the last example why not land with Flap 25 (lower landing sped etc).
In relation to other Boeing aircraft, is there a particular Flap setting that is scripted in the majority of situations, what about Airbus etc?
Any info would be greatly appreciated.