Fuel Venting from left reserve tank

hharney · #1 03-18-10, 08:36 AM

As Dave suggested, more information is needed to determine what may have caused this to happen. NO, it is not normal for the fuel to migrate to the booms and inside the wings as you have described. The main tank(s) on each wing are two separate fuel cells connected by three couplers, two lower and one upper. The only other port on the fuel cell is the line that delivers fuel to the fuel sump in the boom where the quick drain is. Without knowing what maintenance was performed it is difficult to determine what may have caused this problem.

Need more info..........

Roger · #2 03-18-10, 09:53 AM

My 80-H was sitting for a month with minimal fuel in it last year and a few minutes after it was topped off all of the fuel started running out the two holes where the fuel supms stick through the bottom of the wing. If turned out to be the cork gaskets on top of the inboard wings(s) that are the tank inspection plates where the inboard fuel guage pickups are located. We sent for new cork gaskets, replaced, and the have both beeb perfeect ever since. Apparently as they age, if they are left to dry out (minimal fuel for an extended period of time) they start to leak.

And yes you can weld the fuel tanks. There is a guy in I believe Deland, FL that is an expert, who also does symaster refurbishemnt and conversions. If anybody needs the name and nuymber I can get it from my IA.

And lastly, this again points out why is is vital to have your fuel guages working, vs just a good fuel computer. Anything that leaks out is not being picked up by the computer.

hharney · #3 03-18-10, 06:22 PM

When I replaced my gaskets at the fuel sensor port I replaced them with a rubber type gasket. I am pretty sure I sourced them from Yingling in Wichita. I don't know if they are any better than the cork style but time will tell. I didn't have any leaking at the time but I was inspecting all the tanks so they got changed at that time.

I had to have one tank welded at the outlet fitting. It was welded by a certified welder in Kalamazoo.

Photo shows the original cork gasket and the other photo is the tank back in place with the new rubber type gasket.

Cloud9sa · #4 03-18-10, 06:27 PM

Yeah, we just had to replace the cork gaskets on our G model. I 'spose it was due to the cold and dry winter air. Tracy

CO_Skymaster · #5 03-18-10, 11:39 PM

Here is more information:

My aircraft went into annual in October 2009. It had empty aux tanks and about half main tanks. Along with a normal annual inspection I had my A&P working on many other items. One of which was my fuel gauges. The Aux gauges never worked and the main gauges were intermitted. As long as I was going to have the fuel gauges refurbished, I decide to have the entire instrument cluster checked and refurbished. The person working on my fuel gauges recommended that I have my fuel senders checked for functionality. After inspection, it turned out that all were either non functional or had some problems. I had all the fuel senders refurbished also. It was the end of January before the aircraft finally emerge with all the new repairs and upgrades. Performing the entire upgrades place me under financial strain and it has taken about 6 weeks to catch up. The aircraft was sitting out on the ramp during this time. Colorado has temperature highs of about 40s and lows in the teens around this time of year. Yesterday was the first opportunity I had to perform final post annual checks on the aircraft and fill up the main tanks. That's when all the fuel started pouring out from the wing airframe. I checked this morning and it finally stopped. I suspect a few gallons on each side poured out of the tanks.

After thinking about it today, I'm suspecting the gaskets on the fuel senders didn't seal and the fuel flowed inboard and leaked out into the airframe until the fuel level became low enough it could not leak out anymore. I called the A&P this morning and they already have it in the hanger. Hope he has some information for tomorrow.

Karl

Cloud9sa · #6 03-19-10, 09:23 AM

The first pic shows how it was leaking in the wing and down the side of the fuselage. It was only leaking from the inboard tanks, both left and right wings. The second pic shows where the cork gaskets go. The rear gasket was leaking the most--the pic doesn't show how bad the leak really was, because it was wiped clean prior to taking the pic.

Click on the pics for a larger view.

CO_Skymaster · #7 03-19-10, 08:36 PM

That's exactly what the side of my fuselage looked like. They found the problem, when they installed the fuel senders, they didn't tighten down the screws. Glad that was a simple fix. After all the effort to fix and upgrade during the annual, I hate to think here was another problem I had to fix. Thanks for the input everyone.

Karl

hharney · #8 03-20-10, 11:25 AM

FYI
Be careful that the screws are not over tightened. They cause the light metal on the tanks to pull up. This can cause an irregular surface for the gasket and sender unit to seat.

This has been seen by Craig Griswold of Griswold Aviation on other Cessna aircraft. The Skymaster attach points could be different than what he had to repair on other aircraft but just something to be aware of.