Under seat fuel sump smell

[moto657]

I was getting a fuel smell inside if the plane was sitting closed up for several days. Looking around it appeared the pipe thread of the 90 deg adaptor on the Cap of the under seat fuel sump was damp with a very slow leak. I decided to pull the sump to inspect and tighten the fitting while I had the fuel drained to change out the fuel selector.

The nuts and screws were pulled down so tight the retainer plate was deforming, and I had to use a hack saw blade to cut the 2 forward screws.
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When I finally removed the cap and sump it was evident that the leak was more than just the fitting. The entire cap and sump cup were stained blue from av gas.
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Upon inspection both the cap and the cup were badly deformed. The gasket was very hard and it looked like someone attempted to seal it with something at some point. It likely didn't work and they just kept tightening to try and stop the fuel smell. These guys even used Teflon tape on the threads of the flare fittings.
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I replaced the cap, sump cup and gasket with new PMAed replacements from Univair. I went that direction instead of using a Steve's gascolator because it is a direct bolt in. No modification to the fuel lines or floor necessary. The cap is a solid piece of machined aluminum, much more robust than the cast original. So it shouldn't bend again even if someone gets crazy with the torque.


It all went together well and fit as original. The only modification was a small amount of file fitting on the inspection cover where the sump drain comes through. I'm looking forward to a fuel smell free interior!

[PA-16]

I would work on the battery box next, looks like you could fit another battery in there and have a spare. My IA just installed a new cable from the battery to the start switch, my prop is supersonic now when I hit the start button.

[walt.buskey]

Come on over to NH and you can do mine! (Nice job, BTW.)

Ditto on the battery box mod, using Bogert cables.... A great way to ensure none of those valuable electrons get lost on their way to the starter.

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[moto657]

Thanks Walt!

Those old braided wires on the bat box don't look great, but seem to work fine. That little battery cranks the engine over fast!

The light weight battery, and the new battery cables (down stream of the box) were installed in MN by Svenns! They hold the STC for the modification. Not sure why they choose to do the install like this.

[walt.buskey]

Well, what I see as the biggest advantage (besides being copper instead of the original aluminum) is the elimination of both through-the-box bolt connections on the old cables.

I'll also say that my aluminum cables, though I think date back to '56, did still work OK. Cables had already been changed from the relay box to the starter & alternator, but not from the battery to the relay box, so I decided to change all of it when I got the same battery you have.

I see we think alike -- I'm ALWAYS putting dates on stuff....

[Steve Pierce]

Had a Tri-Pacer come in that wasn't charging. Turned out to be the master switch. Seat wasn't installed correctly and discovered the fuel line to the gascolator under the seat kinked and leaking. The gascolator is also installed with hardware store screws/bolts.
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[moto657]

Wow those fuel lines are in BAD shape!

Looks like the bolts on the sump are cranked down so tight the retainer plate is bending. The cap is probably bent like mine.

I'm happy to report I did the first start and taxi/run up tests last night. The fuel system is working well and no leaks so far. While the plane was down for annual I also sent the prop out to be prepitched. 59-->56. I picked up 130 rpm during static run up. Can't wait to fly it later this week!!

[Steve Pierce]

Yep, it is a mess.
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[walt.buskey]

Wow.... some workmanship!

[Glen Geller]

Yep, it is a mess.
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That must be a load-bearing gascolator!