As per the card for the "Blinded Pilot crit" in the 1e core set

"

Blinded Pilot Edit

• Pilot
• The next time you attack, do not roll any attack dice.
• Then flip this card facedown.

Now, If say, a Y-wing uses a Proton bomb which causes a crit to every ship, even those which have shields (Tie advance, Defenders, lambdas, etc). Once the "ship makes its attack, do not roll die, then Flip this card over. Does that then become a full on hull hit, or does it go to the ship's shields??

It becomes a hull damage, even if there are still shields left. Sliding damage under shields was a very potent tactic for a few ships.

3 hours ago, Redd9 said:

It becomes a hull damage, even if there are still shields left.

It does not "become" hull damage. It already is. All damage cards count as 1 damage regardless of which side is up (with the obvious exception of face-up 1st Edition Direct Hit).

4 hours ago, Quarrel said:

... (with the obvious exception of face-up 1st Edition Direct Hit).

Which is always counted as two damage, of course.

So i did rule right. Sweet!