All the small PT-6's I flew had a max of 1090 degrees for two seconds as the start limit with much lower for the limit for longer. But I never operated the -42.
In the end, I think that the critical issue is the rpm when the fuel is selected on regardless of battery voltage(although I suppose there has to be enough juice to maintain the rpm once the fuel is introduced).
But, I don't think there is any minimum required temperature or time limit between starts. I am sure that there are plenty of operators that shut down and start up quickly on warm days.
On last thing, if you hear a CB pop during the start, consider an immediate shutdown as a precaution. I know a guy that told me he toasted an engine because the CB for the starter popped at a critical time just at lightoff. If it was something else...no harm done.
Last edited by JammedStab; 4th Apr 2017 at 15:23.