I have a glow plug problem too. I have a hobbico aerostar 40 trainer with a .46 OS engine in it. The last few times I flew it I noticed the power was dramatically decreased and it even cut out one time and I had to dead stick land it. When I got to looking at the motor I noticed I could unscrew the glow plug by hand. I tighten down the glow plug with a wrench so it is pretty tight when I take it up, it some how keeps working its way loose when its in the air. Does anyone have a solution to why it does that. Should I just lock tight the glow plug in?

Thanks David G.