I've been having a problem with the prop nut coming loose while starting.I have 4 running planes with engines from .25 to .61.It makes no difference which one I try to start,with or w/o spinners,with starter or by hand,about 25% of the time the nut comes loose! Is this in the normal range or am I doing something wrong? I've never had one come loose once running,but I've certainly developed a healthy fear of the prop!How about the nuts with the nylon compression lock?Thanks in advance for your thoughts in this matter!