I know that alot of Flyers will disagree with me, but this is the very reason I like to break-in my Engines mounted on the Plane. Gives me a chance to see how the engine acts on the Plane, and to check to see what is going to shake loose. I own a couple engine test stands, but seldom use them. I just make sure to mount my Plane up high off the ground in my Airplane Stand that I have to keep from working up dust and stuff. I also take alot of safety precautions in case a firewall would decide to give under stress, and I also strap my Plane in the workstand, and secure it down. If I am going to waste 1 1/2 gallons of nitro on a break-in, I just figure that this is a good time to kill two birds with one stone and see how the engine is going to effect the Airplane while mounted. This saves me alot of fuel later, because I don't think it is a good idea to go right from the test stand and right to the airplane, and then right to the air. Something is bound to shake loose! I would prefer to catch these potential problems before I put the airplane in the air.