Help locating the source of a fuel leak

[subpar_bucker]

I wanted to ask the collective for some help with a fuel tank leak. I discovered I had one while calibrating the tank with 20.1 gallons of gas. It's on the filler neck. I have a video here:

https://photos.app.goo.gl/vKK2zW7AT4LNsnke9

I apologize for the lack of quality, it was hard to handle my phone and the light at the same time. Towards the end of the video, if you pause it, you can see the residue left by the leak. What I'm trying to figure out is: do I have 1 leaking rivet, 2 leaking rivets, or is the flange itself leaking?

 

[Webb]

To have fuel in that many places, and on the filler neck, my money is on the hose. Leaking fuel isn’t going to run uphill.

 

[Piper J3]

I used AC Delco 1148963 GM Original Equipment 10-5045 Multi-Purpose Fluorescent Leak Detection Dye to find leaking rivet in fuel tank. Use a strong UV Black Light Flashlight (51 LED’s) to find leak. Source dye and UV light on Amazon. Works a charm….

 

[seagull]

Tighten the hose clamp.

 

[rcarsey]

After seeing your video.. my vote is on the hose clamp (top and/or bottom). I noticed some brown discoloration on the flange, above the two obvious rivets.. see photo..

Also, the two rivets seem to have been dipped in tank sealant.. so for them to be leaking.. hmm.. I'm not buying it. The rivet head-to-flange gap seems to be sealed up good.. so.. I don't think the fuel is coming out of the tank at those rivets. Without any signs of the fuel coming from uphill rivets.. there's only one other place it can be coming from.. and that's the hose clamps. Maybe remove the hose, inspect, reattach. You can overdo those clamps to the point that it starts to deform the aluminum necks.. but "good-n-tight" is about right.

 

[gasman]

Tape paper towel around and over any area that you think is leaking.... It will show up right away as soon as it leaks.
First try under the hose end before a flight with full fuel.

 

[Bob Y]

After finding my fuel leak was coming from my hose clamps too, I replaced the stock worm-gear clamps with constant pressure clamps and haven’t had any issues since. I got mine from the local automotive supply store.

 

[subpar_bucker]

Thanks for all the replies! I'm very happy to hear that it looks like I just didn't tighten up the clamp enough. Will give that a try next time I make it to the airport.

Thanks again for the help everyone!

 

[glongpilot]

Torque the clamps

If you look up the part number on the clamps supplied you'll find they are aircraft grade and have a torque rating. I was getting occasional fuel smell on high power and pitch settings and torquing them seems to have corrected my issue.