Hello,
Some news:
Ok so I received my new HDD (and stressed it) I put it on a free sata slot (on the sata extension board). Because I can't put my ada3 offline I tryed to Replace without "offlining" it. It seemed working the replacing begin but every 45 minutes resilver restart... All is shown as Online and not degraded. I think that the resilvering is working a bit despite it restart because I can pull out the ada3 without loosing my pool...
So now, because it's seems not working I will try to export/disconnect pool, pull out the failed drive, reconstruct new RAIDZ1 and import the pool.
Something else to try before?