I've had my $25 swap meet SuperStar 40 and Thunder Tiger GP-42 built for some time now, now that I think about it it's been about 9 months! But my engine never got broken in. Both the plane and engine were old-new "stock." Yesterday I was running the engine as per instructions and I noticed a gradual drop in RPMs at WOT. It eventually slowed and ran out of fuel, so I filled it back up. It wouldn't start. I checked the glo plug. Checked the fuel lines, and I noticed my fuel tank worked its way backward, cutting off fuel. I made a shim so that it would stay in place, and started it. I alternated throttle settings as per instructions, and still there was that drop in RPMs. It eventually quit, and I tried to start it again. Nothing. I poured a little fuel into the carb. I cranked the engine, and I then saw the "windshield" was coated with glow fuel! I couldn't see where the glow fuel came from! After some close examining, I found it must have leaked out of the head-block seal. The head bolts were a bit loose, so the engine must have been losing compression gradually as the bolts worked their way out until the point where it failed. So I put some blue loctite on, tightened the bolts, charged my radio, did my homework, and went to bed.

My question is: Why did the bolts come loose? Why didn't TT have lock washers or something on those bolts? Was the engine just running a little hotter than I guess it's "supposed" to? I was running 15% nitro (I'm sorry little engine, my hobby store didn't have 5 or 10%!) so maybe that gave it some punch?

Also: EVERYTHING has to be checked after you run the engine on the plane for the first time! I had the fuselage restrained with 2 brake drums and 2 cinder blocks mind you, but that little thing vibrated every screw out a little bit! Loctite everything you won't be messing with and lock-washer everything else! You don't want that plane coming apart on you mid-air or worse: mid-landing! My nose gear was really lose after that!