Seting prim flexible and not flexible via script is possible?

I was trying to change a prim to flexible and after a time to not flexible using:
llSetPrimitiveParams ([PRIM_FLEXIBLE, FALSE, 0, 0, 0, 0, 0, <0,0,0>])
and
llSetPrimitiveParams ([PRIM_FLEXIBLE, TRUE, 0, 0, 0, 0, 0, <0,0,0>])
But the prim is allways flexible.
For instance, if in a colision event the prim is set to flexible, in features the flexible path is checked, but if in a colision event the prim is set to not flexible, in features the flexible path is still checked.
Is this a bug?

i'm not sure i quite understand your problem. but, flexis are always phantom, so the only way to get a collision event from it is if you're using llVolumeDetect.

I was trying to colid to a prim, it turn into flexible and after a time it is back not flexible.
I can colid to the prim, it is flexible, but after a time it still flexible.

collision_start(integer detected)
{ llSetPrimitiveParams ([PRIM_FLEXIBLE, TRUE, 0, 0, 0, 0, 0, <0,0,0>]); }
timer()
{ llSetTimerEvent(0.0); }
{ llSetPrimitiveParams ([PRIM_FLEXIBLE, FALSE, 0, 0, 0, 0, 0, <0,0,0>]); }

I Tryed with "llSleep(open);" instead of "timer()" and it doesn't works too. The prim remains flexible.

llSetTimerEvent(0.0)//set to zero, simply turns off the timer and the timer() event is never reached.

here's one i made with llVolumeDetect, no timer in it at all, it only relies on the built in delay from llSetPrimitiveParams. it doesn't actually turn off flexi, it just removes the force, but you can easily turn it off too
/54/68/339828/1.html

Try changing your code to something like

collision_start(integer detected)
{
   llSetPrimitiveParams ([PRIM_FLEXIBLE, TRUE, 2, 0.3, 2.0, 0.0, 1.0, <0, 0, 0>] );
   llSetTimerEvent(3.0);
}

timer()
{
   llSetTimerEvent(0.0);
   llSetPrimitiveParams ([PRIM_FLEXIBLE, FALSE, 0, 0, 0, 0, 0, <0,0,0>]);
   llSetStatus(STATUS_PHANTOM, FALSE);
}

I'm unsure if the prim will go back to be non-phantom after you make it non-flexy. Might be worth testing, but otherwise, you can always explicitly turn the phantom status back off.

Thanks Vance!
The set phantom false did the trick.