(I also posted this in the ARF/RTF section... sorry about that, but i think it needs to be here, i wish i had though of this earlier!)


I just went out to fly my Avistar today (first time since last summer) , it was perfect outside (minnesota weather) 73 degrees out, and NO WIND!. I did my usual pre-flight checks, and everything seemed to be in order, except it seemed like it took an unusually long time to fill my tank, although at the time I thought nothing of it. But when I started up the engine, something was wrong. The engine bogged a lot even after needle tuning, and there was a little air bubble in the fuel like occasionally. Finally, after some more tweaking, and a new plug my engine was running well. I start down the runway noticing that it was handling oddly. I pull back on the stick after i had sufficient speed, and it climbed out... like a dog... For a second. It suddenly dove down, and i only had enough radio control to slightly pull up just before slamming into a curb. When i brought it back to my "pit" i took off the wing to see why my elevator was acting up. To my surprise, when i looked inside, the plane was full of fuel, and there was smoke coming from my elev. servo. I unplugged the battery as fast as i could, took out the radio tray, sucked the tank dry, and dumped it out. I had a towel and dried it as much as I could. Problem? The screw-type fuel tank seal had come out completely! It then dawned on me why it took so long to fill the tank... i was filling the whole plane! I am still drying and cleaning, and havent yet assessed the damage. Hopefully my radio gear will still work!

Total structural damage besides the fuel damage: a puncture in the wing coating, bent nose-gear, demolished prop, various scuffs and scraped to coating, and my vertical tail-fin snapped off. not too bad i suppose, considering...

Dan,
Actually, "filling up" the plane is not so uncommon. Those hoses easily slip off and it's hard to detect when you've suddenly turned your trainer into a tanker. It sounds like you got off easy and I hope you get another good weekend in MI.

Tom

Just want to say that's a bummer, I feel your pain! Crashed 4 now.. Thanks for the heads up, might save someone else.

I have a ? to add. What could you do to avoid this? If filling up the plane is not all that uncommon is there an extra perflight check that I should do to check fuel lines and such? Maybe fill the plane with the wings off?

I feel your pain...[>:] A few years a go I lost a 3 or 4 yea old Jerry's Little boy basically the same way. Just after take off I was hovering ( luckly not that low) when the engine just quit. I landed with out event, but as it was rolling out I noticed something was dripping from the tail. When I took off the wing, I found that the 10 ounce tank had emptied itself as the rear of the tank split. Lost 3 servos, a reciever, battery, switch harness, and had to retire the plane as the entire fuselage was fuel soaked.

AT this time I was on the fence about going all electric. This was the proverbial straw for me.

To aid in preventing this...

Fuelproof the inside of the area your fuel tank is in and drill a hole in the belly of the aircraft below the tank. Watch for any fuel comming out that hole.

If you properly fuelproofed tha area, then you have a much easier time cleaning up the mess. (fuel soaked foam goes in the trash and wipe it out with a paper towel.) Its quick and easy to do. I used to do this to EVERY airplane. On my 4*40 I didn't do this to... I had a leak and ruined the aircraft. (so now I do them all again.)

I ruined a "Just totally refurburshed" Ultra Sport this way.

Now I fuel proof all the way back to, and including the radio compartment.

I'm sure you all know this, but the Avistar is an ARF, and the fuel tank is already installed into its fwd position. Being a newbie, it would not be common to not think of fuel proofing the aircraft prior to completion. At least since the Avistar was my first plane, I hadn't thought of reviewing the glue points, fuelproofing, and etc, that experience has taught me.

In my case, I found that it was very difficult to fill the tank. Suddenly, the tank plug exploded, and fuel went all over the place. Luckilly, not in the radio compartment, at least in amounts great enough to do damage. The plane is repaired and waiting for free time, which includes fuel proofing the tank area, and strengthening the structure where accessible.

I do like the idea of drilling a hole in the belly under the fuel tank, which I'll do tonight

Lew

I drill a hole, and put in one of those servo grommets....towards the rear
of the tank compartment, near the front wing bulkhead. If fuel is leaking
it will run out on the ground, and you can spot the leak instantly.

I filled up my second r/c plane....a built-up Kadet with fuel. Of course, I
didn't have the plane fuel proofed properly due to inexperience. Ever since
that day, I've made the "leak detector hole".

Dave.

The hole in the rear of the tank compartment is a good idea, and one I'll adopt from this point forward.

I also use a hand crank fuel pump, and have counted the number of revolutions it takes (on average) to fill empty tanks. I now have a good ideaof what it takes, and that if I get to 50 turns of the handle, I've got trouble.
Dennis-