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Greetings,

I'm sure this falls into the category of those who have, and those who will.

I was thinking of flying a round trip cross country flight later this week, so I filled the fuel tank rather than leaving it around 13 gal like I usually do. This proved to be a fatal mistake, at least for the windscreen and canopy. The last part filled so fast that it caught me off guard, and overflowed. It’s hard to estimate how much spilled, but at least a few ounces. Naturally, it got on the windscreen, which immediately crumbled. It ran down the glareshield to the sides, and since it’s a taildragger, it ran downhill toward the rear. I immediately looked at the right side where the canopy is hinged, and it didn’t look like it ran that far down, though there was some on the left side. I wiped both sides and went back to the front. I was thinking that I was lucky it was the relatively easily replaceable windscreen, and not the PITA canopy when I heard some popping. It seems a tiny bit of fuel must have seeped between the canopy and frame on the hinge side, then wicked it’s way to the rear of the hinge screw line. About 1/3 of the screw holes now have cracks extending up a few inches, and I'll be surprised if the rest don't by the time I get back out there.

I've absolutely hated this fueling situation, and it shocks everyone who sees it. It was just a matter of time before this happened. I've filled it so many times that I wasn't being careful enough, and now I'll pay for that mistake with a new windscreen, canopy, and unpleasant labor (I hate trimming canopies).

I do try to look for the silver lining:
#1 is a HUGE one, and that's the fact that it happened in my hangar, and didn't strand me at some other airport.
#2 is that will be that I can finally fit the Peter Anson canopy latch. I've had it for a year, but it was going to conflict with the rivet locations in my canopy frame, so I didn't want to try to install it. Now I'll have no excuse, and it will actually be a nice improvement.
#3 is the temp, which is pleasant now, so not freezing or stifling heat.
#4 is that I will probably go ahead and fit the fuel return Rotax wants. I've been doing without it, and it makes the fuel pressure kinda wonky at times. I might even move my fuel flow meter to below the tank rather than after the gascolator. Since the interior already stinks like gasoline, why not.
#5 is an assumption, and that's being thankful that I can actually get a canopy. That wouldn't be the case for a lot of planes out there.

Of course the down side is the hassle, and cost. I ordered a spare canopy and windscreen since there was a discount for the spare, and since it all has to go truck freight. All total, my momentary lapse of attention will will cost me about $1500.

Rusty (have I mentioned I hate the fuel filler location)

Yikes! That sucks.

That's horrible! I can't begin to tell you how careful I am when refueling. I always put a towel around the opening to catch any drops. I also stick the tank before and make sure to fill it a gallon short. I haven't ever pushed the range so this hasn't been an issue so far.

I've heard it isn't as bad with Avgas. What fuel were you using?

93 octane non-ethanol auto fuel. I wouldn't be surprised if the additives in the auto fuel are harder on the plastic, but 100LL is harder on the engine. I'm usually really careful, and have probably fueled the plane close to 100 times, but it just takes one momentary attention lapse. I'll try to find a way to insure that the canopy can't be damaged again. The windscreen is pretty easy to replace.

I lost the windshield in Onex 107 after filling the tank using 5 gal cans that had leaky spouts. Lesson learned. I bought a battery powered transfer pump with a short hose that had overflow protection in the spout. It would shut off if fuel reached it. I could set the 5 gal tank on the wing and pump 5 gal in 3 minutes and not worry about overflowing. And no drips.

It was my understanding that plexiglass is quite tolerant of hydrocarbons. Polycarbonate....not so much.

Permatex used to offer a plastic cleaner that was available at almost all F.B.O.s. 2-4-D I believe. It was petroleum based and did a fantastic job on plexiglass without damage.

I'd be surprised if fuel was the culprit behind the canopy cracks.

Area 51% wrote:I'd be surprised if fuel was the culprit behind the canopy cracks.

Fuel was 100% certain to be the cause. I don't think fuel would have harmed the acrylic if it spilled on a spot in the open with no edges or drilled holes. In this case, it found screw holes, and a cut edge along the hinge line.

Had I closed the canopy rather than leaving it open, the fuel likely wouldn't have made it to the acrylic. Of course pumping fuel through your windscreen does make you want to open the canopy to vent out the fumes. There has to be a better solution to this.

As for auto shutoff pumps, I might have to revisit that. I used to use battery powered pumps made for 5 gal jugs, and they worked well, but slowly. For the past year, I've been using a fuel cart that I made with a 12V pump, and aluminum tank. The pump came with a non-shutoff nozzle, and I immediately changed it to an auto-shutoff. Unfortunately, that wouldn't start pumping uphill when the hose was empty. I got tired of fighting that, and went back to the standard nozzle.

I wonder if there is a way to modify a canopy and make a square aluminum tray around the filler so you dont have as much risk when filling.

lakespookie wrote:I wonder if there is a way to modify a canopy and make a square aluminum tray around the filler so you dont have as much risk when filling.

It's definitely something I'm looking into. Anything you put there blocks some forward vision though, so making a pan large enough to contain a spill will be an annoyance. There's also the problem of sealing around the tank neck, and vent fitting, though that's doable.

A while back, I printed a funnel of sorts that I figured I'd take if I ever had to fill the tank at another airport, but I've never actually used it. I may revisit this as well, but add an o-ring to the bottom of the funnel that seals well to the fuel filler neck. As it is now, if you overfilled, it would leak around the neck of the funnel.

I did more inspecting today, and I believe there are cracks where fuel could have never touch. I'm starting to believe strong vapors are enough to start a crack, particularly for a hole that's under any stress already. I'll have lots of scrap canopy material to test that theory some day.

Good news is that Sonex is expecting to ship the canopies Fri, via truck freight. I'll probably have them middle to end of next week I imagine.

The Onex looks similar to the Sonex-B design. I had shown an Australian builder what we did on the A model for a catch can, and he came up with a similar concept for the B model. Watch from about 2:50 below.


Perhaps a catch can like that, and a cover for the top would make it better. For our Waiex I carry one of these in the airplane:
https://www.harborfreight.com/solid-non ... 65565.html
That rubber sheet will protect from a splash but not a flood.

Here is the catch can thing I built: