I have a student that has a sweet sounding 5/8 carved bass. We had a couple of weeks of very cold temperatures hear in NY and despite my warnings about humidifying the bass has
developed a bad open top crack

. It runs from the top of the treble sife 'f' hole all the way down to the bottom of the top plate, about 1 inch to the right of the sound post. It's a clean crack down the grain w/ no spintering etc.
Can this be repaired solely thru the 'f' hole or does the top have to come off?
Thanks, BG