Hi all, i'm searching into the manual but i cannot find this answer.

During a Mission how many times a Kill-team can enter a squad mode.

Example: kill-Team enter squad mode and, after some times, drop to 0 cohesion.

When they can enter again into squad mode? (assuming the mission is still not concluded).

thanks

Afaik no, there needs to be another marine in support range and at least one point of cohesion. Should be somewhere in section VII of the core rolebook.

Thanks! But this is valid even if the Mission last days? or Month for example?

Or should i fix some checkpoint in so long mission ?

Well, you can grant the KT new cohesion points for fulfilling certain parts of the mission.

Or should i fix some checkpoint in so long mission ?

Look at p.212 of Corebook. Kill-team will recover cohesion (1 point) after completing any mission objective. Also, GM can grant cohesion point if "Battle-Brothers have completed a particularly monumental task", even if it is not an mission objective.

Also, a Battle-Brother can spend a Fate Point for the specific purpose of restoring one point of Cohesion.

And Ultramarines have a solo mode to restore cohesion.