B727 Flaps / Slats, my two cents.
Dear aviators,
The famous C/B is labelled as LE bypass valve. Just one scenario when it comes into play, like alternate flap use. First touch on the up/down swithc, will extend all LE, then will move the flap motor and by the torque tubes, will move the jackscrews attached to the wing rear spar, and so and so…
The LE slats will remain extended, then the speed limit of 230 kt. because this.
If we have normal hydraulics, we can retract again the LE flaps, using the above mentioned and famous C/B, after closing the red guarded switch to activate the alternate extension system, so now all fluid has access to LE lines an these can be retracted again.
Said that, each LE actuator has a locking device, initially electric, bult in each individual actuator. To unlock we need hyd. pressure in.
My opinion is that the mentioned idea of extending trailing edge flaps alone, was NOT an operating approved procedure at any airline as far as I know.
Inadvertent deployment???? for me it is very remote, however needs more study.
Thanks