We had this issue for a long time with the helicopters where if you press “space-bar” to access the dynamic load-out, it automatically turns the engines on and you cannot access the dynamic load-out. The problem seems to be with Arma and the throttle controls on some flight sticks (The issue has been seen specifically with both the Logitech Extreme 3D Pro and Logitech/Saitek X-56 (Pro). Although we do not have a fix we do have a work around.
1). Max out your throttle with the engines “off”. It will automatically turn your engines on.
2). Scroll wheel or if you have a hot button, use it to turn the engines back “off” and wait for them to spool all the way down.
3). Access dynamic load-out, engines should stay off.
This is a temporary solution as we look deeper into this problem. VileAce and I have the same X52 Pro Flight Control System, yet I have this issue while he doesn’t. We are looking into it and it is not an issue with mods as far as we can tell.