Where to look ?

[istrumit]

Hello all -

In my -10, during the beginning of a flight, when the tanks are full, or near full, I sometimes detect a light to moderate fuel smell.

I have attributed this to fuel coming from the overflow with the fumes getting pulled in the cabin by negative pressure.

I have read the other threads on this subject and various folks have report it on landing or in when in a tight bank.

I only get it with full tanks during climb out.

What is the best way to investigate ?

Thanks,

Scott

[istrumit]

Thread bump.

[Auburntsts]

That's a head scratcher, assuming you have no leaks in the fuel line from the tank to the firewall, in the vent line at the wing root, or around the fuel senders.

My only suggestion would be to close up any holes (wiring, pitot line, and aileron pushrod) in the fuse side at the wing root that might be allowing fumes from the tank vents into the cabin.

[Carl Froehlich]

I'd look at those hard to get right fuel line fittings in the tunnel (fuel valve, fuel pump, fuel flow sender, etc.).

Pull the cover off the tunnel and look for blue stains. As this happens on takeoff look first to the fuel pump as it will be on and those lines pressurized (with the boost pump off those lines are under a slight vacuum from the engine mechanical fuel pump).

Don't overlook the firewall forward fuel fittings as well.

Carl

[istrumit]

I'll remove the covers at the wing root this weekend. Also, the tunnel has a side access panel. I'll have a look in there also.

[istrumit]

I found the issue today.

I took both wing root covers off...no seeps and no leaks found.

I took the tunnel side access panel off (thank you to the original builder for installing one).

And there it was. One of the fuel line couplings down stream of the aux pump was covered and caked in dried blue residue, with quite a bit on the floor of the tunnel also.

I tightened it, ran the aux pump with engine off. Test flew the airplane with the aux pump running the whole time...no more leaks.

For all you RVers out there, trust your nose...this had been leaking for probably a very long time.