fuel tank, fittings and sender questions

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fuel tank, fittings and sender questions

Postby 13brv3 » Wed Jun 23, 2021 4:12 pm

Greetings,

I'm finishing up an older Onex kit that has the molded in fittings in the fuel tank. I've noticed that they have switched to using the oops fittings now rather than molded in fittings. From what I can see, the fittings look pretty secure, and I know that over tightening the molded in fittings will cause them to leak, but are they still subject to leak eventually if you do everything right? I guess the question is whether I should just replace the fittings now before installing the tank for the first time? A fuel leak would be very annoying, so if it's likely I'll eventually need to install the oops fittings, now would be now would be the best time.

Next question is about capacitive fuel senders. I've had the Sonex sender on order for weeks now with no ETA, so I don't have it to measure. The instructions say to trim the length, but I read somewhere that the only reason you trim the length is so you can install and remove the sender with the tank installed. Is that true? The bottom of the sump to floor certainly is shorter than the sender would be if it reached the top of the tank, so this seems plausible. I'd certainly like the sender to reach the top of the tank, even if it means not being able to remove it when the tank is installed.

I did find a number of posts with good info on installing the oops fittings, so thanks to the archive and original posters for those.

Thanks,
Rusty
Rusty
Onex- Rotax 912 (160 hours and counting)
Fixed wing, gyroplane, A&P
13brv3
 
Posts: 466
Joined: Fri Sep 25, 2015 11:59 am
Location: Tellico Plains, TN

Re: fuel tank, fittings and sender questions

Postby WesRagle » Wed Jun 23, 2021 7:54 pm

Hi Rusty,

Replacing the molded fittings with oops fittings is a judgment call. I decided to replace the molded in fittings up front. So far so good. My experience can be found here: https://sonexbuilders.net/viewtopic.php?f=5&t=4903&start=30#p37662.

I did not have to modify my capacitive fuel sender. It fit perfect right out of the box.

Good Luck,

Wes
Wes Ragle
Onex #89
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Re: fuel tank, fittings and sender questions

Postby pappas » Wed Jun 23, 2021 9:23 pm

I assume you are waiting for the Princeton capacitive fuel sender. I have used them several times and they work well. I have spoken to the company owner once or twice on the phone. This is not a big production shop. He makes these in small quantities to order and does not keep a large inventory.

But he is a good guy and I don't have anything bad to say about him or his product. I got the feeling from him that he does it for the love of the sport. Hang in there, it will show up and you will be pleased with how it works and how easy it is to program. The instructions for fitting it are simple and clear.
Lou Pappas
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Re: fuel tank, fittings and sender questions

Postby 13brv3 » Thu Jun 24, 2021 11:53 am

Thanks for the link Wes, but I had already read the excellent posts in my previous searches.

I just spend an hour or so reading tank leak posts on the other sub-forums, and that was enough to convince me to do something. Since my tank is a number of years old already, and since I've noticed a few fairly deep cuts in it (probably in transport, or handling somewhere along the line), I just ordered a new tank that will come with the oops fittings. That should give me new plastic, no damage, and no extra holes or defective fittings. It's probably an overkill solution, but I think the peace of mind will be worth the cost.

I did hear from Princeton a few minutes ago, and they said the sensor will ship tomorrow, so that's good news. If I don't have to trim it, I won't. If the probe ever needs to be replaced, and I don't want to pull the tank, I can always cut or bend the probe as I remove it, then install a trimmed probe, or maybe a bendable probe as the replacement.

Thanks,
Rusty
Rusty
Onex- Rotax 912 (160 hours and counting)
Fixed wing, gyroplane, A&P
13brv3
 
Posts: 466
Joined: Fri Sep 25, 2015 11:59 am
Location: Tellico Plains, TN


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