I had my UCD out for the first time this year today and ran into a problem. Went through a pretty thorough preflight check and felt pretty good about putting it in the air. Fueled up the plane and ran the motor pretty hard on the ground and it seeemed OK. Took off into the wind and set her sailing. Flew for about 5 minutes and pulled into a hover. Lucky I was well off the ground. The engine died and I had to dead stick it in a pretty voilent wind. Damn near ruined it trying to get it back to the runway, but ended up sitting it down. Landing was a little hard, but I wasn't too worried about it. When I went over to retreive the plane it was very oily with fuel all over it. I After I noticed that fuel was dripping out of the front of the plane! Ouch, I pulled the wing off and tried to diagnise what happened to the tank. Turns out the rubber stopper came out of the tank. Like3 I sid I did a pretty thorough pre flight, but it didn't include inspecting the tank setup. My tank is a pain in the ass to assess in the UCD so I didn't even think about looking at it.

Heres the fun part, I'm still trying to figure out what exactly happened. At first I thought maybe the stopper came out when I landed considering it was kinda hard, but if that was the case I would not have had the fuel all over the outside of my plane. But on the other hand, if the stopper came out in mid flight then why is there fuel all over the outside of the plane? There is some fuel that spilled inside the plane, but only behind the firewall. There is no fuel in the cabin or on the throttle servo [sm=confused.gif]. My tank is actually situated about 1/2 of the way back toward CG.

I'm using a cline regulator and Saito 100 and I'm wondering if there is possibly something wrong with my cline. For example if the muffler pressurized the tank and the regulator was broke then maybe the pressure built up enough to push the stopper out of the tank. The check valve would've prevented the pressure from escaping causing it to reach the critical point? Who knows. The stock UCD tank still appears to be in good shape at first glance.

I may try putting the thing back together without the cline and seeing if I can get it running well without one. I'm also going to make sure I put thread lock on the stopper screw.

I don't know exactly how much fuel was soaked up by the plane, but it doesn't look like a ton. I've heard there is some type of spray I can get form Wal Mart that will help with fuel soasked balsa. Anyone know the name of this?