Boeing 747-400 water landing evacuation procedure

[back to Boeing]

Originally Posted by wiggy

As I recall it ( with a "it's been ten years plus so health warning") the inboard/mid-span leading edges retract on selection of reverse to prevent them being damaged during reverse thrust operation ( ?FOD). Once reverse is cancelled the LEs should then automatically return to the position appropriate to the selected Flap setting..(and FWIW the slats work in harness/are controlled by the Flap setting/Flap lever, there's no separate slats control). Bearing that in mind..

1. On approach/touchdown with Flap selected the inboard/mid LEs will be "out".

2. On roll out with reverse selected the inboard/mid LEs will motor "in",

3. Once reverse is cancelled, usually towards the very end of the rollout, those LEs will then motor "out" again because usually at that point landing flap is still selected,

4. Once off the runway and when the after landing procedure is performed the flap is selected up and the LEs will motor "in" again..

That's the theory.....

Unless the air/ground reverse logic fails when you take off out of JNB and then you have a very exciting take off 😱