Fiberglass fuel tank woes

C_Parker

Pre-takeoff checklist
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Cessna 182F

Both of my tanks are sagging out towards the end, my right tank is pushing down on the vent tube and creating a belly. In the left tank it has a come down enough that it has broken the vent tube.

Have you guys ever seen this before? Recommended course of action? I’ve contacted Butch from Hartwig because they own the STC, but he’s deer hunting this week.
 

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Unsafe manufactures defect. Have your mechanic report this to FAA.
 
Unknown, but it does have the mogas STC so I assume so.
 
Auto fuel (particularly E-10) and many fiberglass resins do not play well together. That's why I elected to fabricate new tanks for my E-AB ride out of aluminum.
 
but it does have the mogas STC so I assume so.
FYI: there are certain types of fiberglass that do not mix with ethanol gasoline where the glass resin dissolves. There is a rather long history of this in the boating community. And even though most/all auto fuel STCs prohibit use of ethanol gasoline have seen where this requirement was not followed. Perhaps question Hartwig on this and if this is a possible ethanol/resin issue you may want to look into the entire fuel system.
 
Bill Barton wasn't included in the deal with Hartwig. He'd of fixed that overnight.
 
The fuel compatibility issue is a definitely a good question. I'll have to see what Butch says when he gets back from his trip.

If the tanks are indeed compromised, I think the only option at this point is a replacing them with bladders?
 
I don’t know much about these but wondering if parked outside could extreme prolonged heat do that???
 
Guys, so if these tanks are junk, is my only option to go with bladders?
 
What would put downward pressure on the top of the tank to cause that?
 
What would put downward pressure on the top of the tank to cause that?
No pressure, gravity. If there was ethanol gas in the tank and dissolved/softened the resin then the glass fiber has no rigidity.
 
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FYI: there are certain types of fiberglass that do not mix with ethanol gasoline where the glass resin dissolves. There is a rather long history of this in the boating community.

My 50 year old Howard v-drive has fiberglass tanks. When I bought it, it hadn't been run since the mid 70s, so the tanks were in good shape.

The fix was to run 105 octane leaded racing fuel. The 427 Ford FE and the fuel tanks liked it, and I definitely enjoyed the perfume it generated after being ignited and burned.

:D
 
No pressure, gravity. If there was ethanol gas in the tank and dissolved/softened the resin then the glass fiber has no rigidity.
How is gravity going to cause a fiberglass tank wall to break an aluminum vent tube?
 
I think that question would best be answered by your mechanic.
That will be the best answer, but if the problem was caused by improper fuel, perhaps replacing the tanks with similar tanks (and checking out the entire fuel system) would be fine, but be sure to placard the fuel area with a warning not to use improper fuels. And then DON'T use any ethanol fuel.
 
How is gravity going to cause a fiberglass tank wall to break an aluminum vent tube?
Gravity didn't break the tube. Gravity assisted in deforming the tank which sagged and made a stress point on the tube. If I were to guess, the movement of fuel on the tube work hardened the tube at that tank interference point and it eventually broke there as noted in the pic.
 
I also struggled with the idea of heat sagging causing the tube to break, but the other potential is that the tanks were installed used and already a little deformed and all it took was a little pressure during install to break the tube. Either way, still waiting to hear back from Butch on repair options if there are any. If there are no options I'll have to pull the wings and install bladders. Either way, this is going to be a very expensive problem....
 
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