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-   -   RV-8A fuel smell after landing (https://vansairforce.net/community/showthread.php?t=207761)

pv9 07-03-2022 09:02 PM

RV-8A fuel smell after landing
 
Hi folks:
I just “adopted” my recently purchased and RV-8A and did my transition training. It is a wonderful aircraft to fly. Lots of minor squawks but a possibly worriesome one that I wanted to consult the experts on this forum on.
I have a carbureted O-360.
After landing with the fuel boost pump on and mixture rich I get a smell of fuel that goes away. This happens every time on landing:

Carl Froehlich 07-04-2022 08:34 AM

Look for the telltale blue stains on the fuel runs aft of the firewall, including wing root. Don’t forget to look at the vent lines as well.

Here a small air leak will show up as a fuel smell after running the boost pump for landing. The RV-8/8A fuel line plumbing is challenging - and a source of hours of “loosing your religion” work.

Carl

pv9 07-04-2022 09:27 AM

Quote:

Originally Posted by Carl Froehlich (Post 1617746)
Look for the telltale blue stains on the fuel runs aft of the firewall, including wing root. Don’t forget to look at the vent lines as well.

Here a small air leak will show up as a fuel smell after running the boost pump for landing. The RV-8/8A fuel line plumbing is challenging - and a source of hours of “loosing your religion” work.

Carl

Thank you so much. I will troubleshoot based on this valuable tip!

Mikeyb 07-04-2022 10:15 AM

I had a tank leak develop at the famous aft baffle seam. It was small enough I couldn’t see any evidence of it externally but found it with a borescope. I could smell it in the cockpit after landing for some reason.

Good hunting

Ironflight 07-04-2022 10:34 AM

Probably not your case, but the -8 is well known to give a fuel smell with full tanks in the pattern because it burps a little fuel out the tank vents, and this migrates into the under-wing passenger vent. It seems more common with a full right tank than left (probably because that is the side the vent is on).

If you’re sure it only occurs with the pump on, then you might well have a leak somewhere - but since you’re new to the -8, figured you should know of this “characteristic”. I think other models will burp fuel out the vents as well, but they don’t have an under-wing vent to pipe the fuel into the cockpit.

Check6 07-04-2022 11:00 AM

Value of VAF
 
Ironflight,
This is one of the many reasons this VAF forum is so valuable! Pearls like this. Funny thing was when I saw the post I thought what the heck, then read it and went oh yeah, just took that "uniqueness" for granted everyone else knows this. Nice to keep sharing the nuisances of each airplane type.
Thanks!

pv9 07-04-2022 02:04 PM

1 Attachment(s)
Quote:

Originally Posted by Ironflight (Post 1617762)
Probably not your case, but the -8 is well known to give a fuel smell with full tanks in the pattern because it burps a little fuel out the tank vents, and this migrates into the under-wing passenger vent. It seems more common with a full right tank than left (probably because that is the side the vent is on).

If you’re sure it only occurs with the pump on, then you might well have a leak somewhere - but since you’re new to the -8, figured you should know of this “characteristic”. I think other models will burp fuel out the vents as well, but they don’t have an under-wing vent to pipe the fuel into the cockpit.

I found these blue telltale signs by the fuel flow transducer cube.
The area around it was dry but there was an oily residue near the corners. It appears that there is a very small amount of vapor coming from there. Aircraft is grounded until this can be traced and fixed!

John Tierney 07-04-2022 02:24 PM

Its hard to tell from the photo, but it looks like there may be Teflon tape on the blue threaded fitting going into the red cube. If that is the case it should be removed and replace with a more appropriate thread sealant (lots of debate on VAF regarding favorite products).

pv9 07-04-2022 02:57 PM

Quote:

Originally Posted by John Tierney (Post 1617783)
Its hard to tell from the photo, but it looks like there may be Teflon tape on the blue threaded fitting going into the red cube. If that is the case it should be removed and replace with a more appropriate thread sealant (lots of debate on VAF regarding favorite products).

It could be teflon tape. If so, serious builder error. I'm going to have to inspect everything at this point.

pv9 07-04-2022 05:08 PM

Looks like this was a recent “repair” by an A&P who attempted to fix a faulty fuel PSI reading. He put a mechanical gauge in line with the cube transducer to check the PSI and then re-sealed it with Teflon tape.
Lesson learned. Do your own repairs, trust almost nobody.


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