Ah, the 'Blue' Gas Shower!

[SkyKing]

GMAs,

On our '77 P-model, I have never let it sit with empty tanks... always keep at least 40 to 50 gallons per side, so I don't quite understand how the gasket could have dried out. Plus I keep the plane hangared, so it's protected from the sun and elements.

Inspected things yesterday... with the right fuel gage indicating about 38 gallons, there's no fuel leaking and no new stains anywhere that I could see. Because the left wing has about 65 gallons, the airplane is not setting level... the right wing is canted up a bit higher than normal, so any fuel in any of the three outboard tanks is going to the inboard tank or at least leveling out in the inboard and the first tank outside of the boom. Obviously, if there were a crack in the inboard tank, it would be leaking now, but I suspect you may be correct - that the aft inspection hole cover/gasket was leaking when I topped it off.

With the flaps extended and looking with a mirror and flashlight through the inboard flap rod actuator opening, the fuel stain concentration in the right wing appears to be confined to the aft-inboard area of the lower wing skin along the lower rear spar and does not extend outboard much farther than the furthest outboard fuel drain valve and I don't see any evidence of staining in the area directly beneath or beyond the inboard flap bellcrank.

The heaviest concentraion of stains appear to be in line with and just below the aft cover plate/inspection hole of the inboard tank, which is of course, underneath the wing skin. Was this part of the 337 an "Edsel" design? Hhmmm. And looking at the screws and paint on top of the inboard tank area, it's obvious the upper panel has never been off the plane. BTW, the interior areas are bright and shiny and no corrosion of any kind.

With the square underside inspection panel off as well as the lower aft fairing removed, looking up between the wing inboard rib area and the fuselage, there are no fuel stains forward of the aft fuel line/hose connection to the fuselage. However, what puzzles me is the pictorial in the parts manual for my serial number (0286) doesn't quite match, as I see TWO aft fuel line/hoses coming from the tank and connecting to the fuselage and Figure 114A only shows ONE! Hhmmm.

GMAs, you mentioned something about the tank vent line hookups getting dry and hard and possibly leaking... that this could cause the problem... could you digress a little on that... I don't quite follow. Aren't the vent lines made of aluminum? I'm now wondering if that might be the problem as this same thing happened to me about a year ago when I stopped for fuel along the way and topped off... when I got home there was fuel stains in the same general area, but with 65 gallons a side at that time, there was no leaking that I could detect.

I also opened up the top side inspection cover and inspected the area around the Penny Cap fuel sensor and the only thing I see there is the dark Cessna glue they spread around when installing things... but it is dry on top and no signs of any leakage whatsoever.

Well, that's the rundown for now... I'm REAL curious about those vent lines drying out??? I can't imagine the aft inspection hole of that inboard tank has let go. Anybody know what the capacity of the inboard tank is?

SkyKing