CannonFodderSE

I've been doing small mission created with Briefing Room for the Huey. Close to 50% of the time when the mission starts and the helo spawns there is a bang and the main rotor goes flying off without the rest of the helo. Once the mission is running I can choose a new slot or even the same slot and all is good. What can I do to fix this? Any logs I can be looking at? Thanks! Randy Bancroft