It has and can happen.
A helmet can become worn or damaged.Do not wear a helmet that has been in an accident, it might be cracked and not protect another time!
Wear a full-face helmet.
He is on the Toronta Blue Jays. Size 8, largest ever made for MLB.
If the shell is cracked, yes, it's time for a new one.
No why would you buy a new helmet every time you crash. If it is cracked then you should get a new helmet. I have had at least 11 crashes w/ my Bad Lieutenant from Giro and I've had it for about 2-3 years.
cracked head or knot or scrape
No.
open the vents, keep the visor open all the way or at least cracked open
it protects your head
yes
Yes
with glue