Original Posted By: "Rob Stapleton, Jr."
First I guess I should state that I am a non-builder owner. I bought my GN-1 3 years ago, and have flown it around 300hrs. It has about 500hrs total time, and has been a great plane.I took a friend up for a brief flight this evening, and when we landed I started removing all of my fuel lines and fittings, I intend to replace the rubber lines with stainless braided lines. My fuel tank is a fiberglass 18.3 gallon tank in the nose. I was pulling the fuel line off the nipple on the fuel valve at the bottom of the tank, and the entire fuel valve, strainer, and all fittings broke right off the bottom of the tank! This left the ~3/8" hole in the bottom of the tank wide open, which poured some fuel into the cockpit until I was able to stick my finger in the hole. I was working through an inspection hole on the side of the fuse directly behind the firewall. There were at least 12 gallons of fuel in the tank, which we had to empty using a coffee can, one can at a time. Luckily I had a friend there with me, I would've been in trouble if I had been working alone like I usually am. As you can imagine, this situation in itself created a fire hazard in the hangar.I was not using excessive force on the fuel line, a moderate kick by the passenger would've had the same effect. It would've resulting in immediate engine failure, a forced landing, and the emptying of the fuel tank into the cockpit! A very, very bad situation! That is something for builders to take note of, make sure your fuel fittings are very, very sturdy! I was replacing the rubber fuel lines with stainless braided lines to increase the strength of the whole system, little did I know that the fuel tank fitting probably had less than 10% of the strength of the rubber fuel lines that were installed.Attached are three pictures of the broken fitting, as well as one picture of the fitting I had taken several weeks ago to help me decide what I needed to do to change the valve and hoses. As you can see, the fitting and strainer were held to the tank only by a large glob of fiberglass resin. There was no fiber in this glob, so the mechanical bond to the tank was relatively weak. The "blob" was also placed on the tank after the tank had cured, so the resins were not actually mixed, the blob was just "stuck" on the cured tank. This was the only mechanical bond between the tank fitting and the tank.Now, I need to determine what to do to get the plane airworthy. I can build another tank, or I could try to determine a way to attach my new fuel valve to the old tank. Of course, my primary concern is being able to attach the valve in a very secure manner. I believe replacing the tank would legally require a new restricted fly-off period by the local FSDO as it is a major change. I belive replacing the the existing fuel valve would not require a new fly-off period. Any tips anyone can give me on a good method to secure a new valve to the existing tank would be greatly appreciated. I fly this plane a lot, and flying season is here so I hate to have it down, but repairing it properly and safely is my primary concern. I would like the new valve to be mounted to the tank using a method that is strong enough that it would damage the tank before the fitting would just fall off like this. I will remove the tank this week and post a few pictures.Thanks for any suggestions or input!Steve RuseNorman, OK________________________________________________________________________________
Pietenpol-List: Bad news - broken fuel tank fitting & warning to builders
RE: Pietenpol-List: Bad news - broken fuel tank fitting & warning to builders
Original Posted By:
RE: Pietenpol-List: Bad news - broken fuel tank fitting & warning to builders
Original Posted By: owner-pietenpol-list-server(at)matronics.com
I see that there is an aluminum disc attached to that whole mess. You mightconsider epoxying two .040 aluminum straps (so that they will fit thru thehole in the bottom) in a place where you can rivet or screw the 'disc' tothem. This in conjunction with cleaning and patching. That might give you afitting that is less likely to pull out. Also consider mounting that shutoff some where on the firewall, or the fuse side where it can be easilyreached, but secure.Gary Boothe Cool, CA WW Conversion 90% done, Working on Tail Group (6 ribs down.) _____
I see that there is an aluminum disc attached to that whole mess. You mightconsider epoxying two .040 aluminum straps (so that they will fit thru thehole in the bottom) in a place where you can rivet or screw the 'disc' tothem. This in conjunction with cleaning and patching. That might give you afitting that is less likely to pull out. Also consider mounting that shutoff some where on the firewall, or the fuse side where it can be easilyreached, but secure.Gary Boothe Cool, CA WW Conversion 90% done, Working on Tail Group (6 ribs down.) _____
Re: Pietenpol-List: Bad news - broken fuel tank fitting & warning to builders
Original Posted By: "Gary Boothe"
If the tank is not weak elsewhere, I would clean it thoroughly, repair appropriately with plenty of fiberglass and then slosh the tank with POR15 to prevent the ethanol blends form affecting it further. I believe the ethanol is a likely cause of your break. Others have fixed the problem with the POR15 tank sealer.Michael________________________________________________________________________________
If the tank is not weak elsewhere, I would clean it thoroughly, repair appropriately with plenty of fiberglass and then slosh the tank with POR15 to prevent the ethanol blends form affecting it further. I believe the ethanol is a likely cause of your break. Others have fixed the problem with the POR15 tank sealer.Michael________________________________________________________________________________
RE: Pietenpol-List: Bad news - broken fuel tank fitting & warning to builders
Original Posted By: owner-pietenpol-list-server(at)matronics.com
Looks from the pictures that the fitting just came unbonded from the tank,not a break of the glass used to make the tank. Correct?For one thing, looks like the metal was not bonded to the tank at all.Looks like the metal was not even roughed up properly for gluing it. Themetal should be sanded with something like 60 grit sand paper then cleanedwith MEK. Or is the hole in the tank just so big that there is nothing toglue to? Putting another four or five layers of glass on the tank insomething like six or eight inch round pieces over the hole should fix thatproblem.Also, is the tank resin the same thing that was used to glue the metal on?Perhaps a vinyl ester or polyester resin tank that had the metal glued onwith epoxy?Was the tank roughed up properly before glueing the metal on? My favoritething to use is a wire wheel on a drill. That does a much better job thansand paper does.Brian KrautEngineering Alternatives, Inc.www.engalt.com------------------------------------------------------------------------------
Looks from the pictures that the fitting just came unbonded from the tank,not a break of the glass used to make the tank. Correct?For one thing, looks like the metal was not bonded to the tank at all.Looks like the metal was not even roughed up properly for gluing it. Themetal should be sanded with something like 60 grit sand paper then cleanedwith MEK. Or is the hole in the tank just so big that there is nothing toglue to? Putting another four or five layers of glass on the tank insomething like six or eight inch round pieces over the hole should fix thatproblem.Also, is the tank resin the same thing that was used to glue the metal on?Perhaps a vinyl ester or polyester resin tank that had the metal glued onwith epoxy?Was the tank roughed up properly before glueing the metal on? My favoritething to use is a wire wheel on a drill. That does a much better job thansand paper does.Brian KrautEngineering Alternatives, Inc.www.engalt.com------------------------------------------------------------------------------