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!