A serious design flaw has been discovered in the standard issue visor for Kerbal space suits. Closing the visor can lead to immediate spontaneous combustion.
If you or your team are currently using visors you should immediately remove them. A recall and replacement program is currently being arranged.
Steps to reproduce:
Start an EVA in low Kerbal orbit.
Move 10k or more away from your craft by not reading the manual and pressing keys repeatedly.
Wait for the backpack thrusters to run out of fuel (you can read the manual just before this point if you like, but it won’t help now)
Wait for initial reentry
At the point where your Kerbinaught is at maximum heat stress, close the visor.
Footnote: The manufacturers of the visor strongly deny their product is at fault, and suggest other factors lead to the death.