FWIW, I've been running ethanol free gas also. My guess is it's partly chemicaly induced but also flexing of the structure induced. As i understand, the tank adds some strength to the wing, so as the wing flexes so does the tank. Good Luck, Bryce
Lots of others have said the same. Someone sent me an ad about an epoxy sloshing for motorcyle tanks, and it looks like a winner for leaking aircraft tanks of any type. I dont have it on this new puter, but can find it in my printouts if anyone needs it.
ED in MO
I bought my tanks direct from Ron's Fiberglass, the one who made tanks for Skystar or Denny. He no longer makes the tanks since Kitfox took over.
I tried to get him to tell me what epoxy was used, and he only would say, "It's commercial grade, and you cant buy it."
Still would like to know what they are made of. I have always used the West system for personal use. The Ren 1710 epoxies that I used commercially are too costly for small home projects.
ED in MO
Not sure if the Avid A, B, C and Mk-IV model tank fittings are similar (I used Kitfox tanks in my Mk-IV), but I do know Airdale Flyer tanks are similar to the Magnum tanks with a 3/8" NPT outlet. I believe it used the finger strainer from Aircraft Spruce (p/n #05-17700, 3/8" Male NPT x 1/4" Female NPT) screwed into the tank, and then a brass straight 1/4" NPT with 3/8 tubing barb screwed into that. At least, that's what I have in my notes.
Lucky? Maybe. I'm 100% convinced that ethanol in autogas plays a huge part in speeding up the deterioration of the fiberglass wing tanks made with polyester resin. I also think that the way Avid and [old] Airdale globbed on the baffle adhesive when making the tanks, there is a very high probability of small chunks breaking off and ending up in your tank, regardless what fuel flavor you use. A GPH gauge may be helpful identifying a reduced flow as fibers slowly clog an in-line filter, but catch a chunk big enough to block the outlet and it won't be much consolation when the fan stops. Seems like cheap insurance to me....
My KF3 had the flaperon hanger mods and I can tell you they are a whole lot beefier than simple, stand-alone ply rib tails. There are many ways to reinforce the flaperon hanger rib tails, but this one has the benefit of manufacturer design, PFA/CAA approval and can be retrofitted to finished wings with minimal effort. The fabric patches from the mod on my wings were fairly discrete and did not stick out at all. I like the way the reinforcements is riveted to the metal trailing edge, seems very strong to me. Here's the SB info and pic.
SERVICE BULLETIN #9
SUBJECT: Flaperon hanger rib-MANDATORY
TO: Kitfoxâ„¢ MODEL I, II, III owners
FROM: Denney Aerocraft Company
There have been two cases of Kitfoxâ„¢ flaperon hanger rib failure documented in the United Kingdom. In both cases the failure appeared to be from side load overstress. Both aircraft had been in recent prior ground accidents. One was in an automobile accident while being transported on a trailer. The other mishap involved a nose-over upon landing. In both cases it is very likely that there were excessive side loads placed on the flaperon hangers which could have contributed to the subsequent failures. In the latter case the failure occurred on the ground during a period of engine operation at very low RPMâ€™s including engine operation on one cylinder, which caused the entire aircraft to shake violently. There was no personal injury to any persons in either case.
As a result of these occurrences the PFA/CAA in England have grounded the entire Kitfoxâ„¢ fleet, subject to a modification of the flaperon hanger ribs that will meet or exceed United States FAR Part 23 requirements for control surface mass-balance supporting structure.
We have designed and tested reinforcements for the flaperon hanger ribs that can be readily fitted to Kitfoxâ„¢ wings under construction or retro fitted to wings already completed. These modified ribs will withstand up to 150 lbs side load each when in reality the load will most likely be spread over the 5 hanger ribs. FAR 23 requires a side load capability of 12Gâ€™s and 24 Gâ€™s normal to the plane of the control surface. The flaperon with the Denney Aerocraft mass balance weighs 7 pounds so you can see that it will withstand a side load of over 21 Gâ€™s with the modification. We also tested standard un-modified ribs and they withstood 90 lbs of side load (12Gâ€™s). In essence they met the Part 23 requirement for side loads without the reinforcement.
To meet the requirements of FAR 23 for in-plane loads of 24 Gâ€™s the reinforcement must be installed on the two outboard ribs. (This assumes you have positioned your Denney Aerocraft Co supplied mass-balance in the prescribed position near the outboard end of the flaperon). You should also install the reinforcement on each inboard rib to compensate for slack in the bearing or failure of the fuselage/turtledeck support bearing. If you desire to reinforce all ten flaperon hanger ribs that is Ok but not necessary UNLESS you have installed the rod type mass-balance inserted in the leading edge of the flaperon as some have done in the U.K. If you have used the rod-type mass balance method then you should reinforce all 10 flaperon hanger ribs.
The reinforcements consist of left and right .025â€ 2024-T3 aluminum angles riveted to each side of each flaperon hanger rib end. Each angle is 8 inches long and tapers from a depth of 1.2 inches to .8 inches with a flange of .4 inch. This flange fits flush against the bottom of the rib cap strip. The reinforcement angles are fastened to the tail of each hanger rib with 6 each 1/8 inch x 5/16 inch long blind â€œPOPâ€ rivets. Each aluminum angle is also riveted to the rib cap strip with 3 each 3/32 inch x 3/16 inch rivets. The builder will have to round the ends of each reinforcement angle to match the rib. He can at his option apply FSA-2 structural adhesive or the equivalent to the mating surfaces for increased joint strength. If this is done the reinforcement angle should be cleaned with acetone or MEK and rough sanded with 100 grit sandpaper.
To retrofit the reinforcement strips to a wing that is already covered, you will have to slit the fabric from the trailing edge about 8 inches forward along the centerline of the bottom of the hanger rib. Slit the fabric along the trailing edge about 6 inches on each side of the rib. Then you can pull the flap of fabric back away from the rib so you can drill rivet holes and install the reinforcement angles.
To repair the fabric you will have to remove the paint and dope down to bare fabric with Stits reducer, MEK, or other suitable solvent. Then use fabric tape to cover the slits and use Stits Poly-Tac, Poly-Brush, and Poly-Spray to attach and coat the tapes. Heat-shrink the patches and repaired areas to restore tautness to those areas. Repaint.
This modification is recommended but not required except in the U.K. It is available to you from Denney Aerocraft Co. at a cost $30.00 which includes shipping costs. You could also fabricate it yourself.
NOTE: Do not idle or run the engine in the low RPM range of 0-2000 RPM except passing through this range in starting and shutdown.
After a particularly shitty 2 weeks at work, and an even shittier first day at home, I loaded up and headed to the lodge at 11 PM. Good thing it never gets dark around here! A very smooth hour n a half flight and I was at my paradise get away and hide from reality place.
A few shots of the stay there. It was 7 days of pure bliss.
I guess I have been lucky! I cleaned my tanks out during the rebuild and have never had a problem, and there are no finger strainers on mine. I wonder if it has something to do with the real gas I get up here
KITFOX SITE had a mod with drawings of the reinforcement that the UK required. Might also be in some manuals?
Believe it was .025 aluminum with several rivets, bent 90 and went full width of hanger and up into rib several inches. Think trailing edge was slit?
Since I am going with BIG flaps and ailerons, I am adding 1/8 x 1 x 9 flat aluminum on each side of hanger, but I tend to overbuild.
Somewhere in between might be a good compromise.
ED in MO
P.S. Added: BELIEVE this was in Service Bulletins.
I've never had the opportunity to see an Avid Cat or Amphib up close so those are interesting pics, thanks for posting. Pretty weird looking engine mount, almost looks like an old flat plate style for a 582, but that can't be right?! Everything appears to be in relatively good condition for sitting so long, only minimal rust. Was that really stored in an unheated PA garage or barn for all these years? If so that's amazing given our weather and humidity.
Should be a fun project with a unique ending so please do keep us up to date with your progress.
Well, I have seen enough crap come out of my tanks that I would never fly without finger strainers. Inspecting and cleaning them is also on my condition inspection list. I think it is a simple reality given the materials and way these tanks were manufactured, plus our propensity for auto gas with ethanol, you're gonna get the old adhesive chunks and fibers loosening up. That's why I won't use in-line filters between the wing and header tanks and prefer a header tank with sump and gascolator combo. I also eliminated the 90* degree elbow tank outlet fittings which a lot of folks claimed was a real junk trap without the screens. At least Avid owners didn't have to deal with the Kreem tank slosh issue too. Check the flaking Kreem pic in this thread and count your blessings! Fuel Strainers
Great pictures! Looks like a heck of a good time. Us flat landers over here on the east side of Alberta only dream about being able to play in the mountains. Maybe this summer i'll have time to make a trip to BC. Have some relatives in Summerland that need visiting.
Keep posting those pictures. Its great inspiration to the rest of us!
Yes,I get that crap all the time in my fiberglass tanks on my MKIV
I clean the finger screens regularly
flying without finger screens seems ridiculous
I can't believe they would even send kits out without finger screens
cleaning them is a part of regular maintenance IMHO
without finger screens,you would think anyone without them would definitely be using a filter just to add fuel to there aircraft
just to keep any crap/bugs whatever, out of the system
That ... is the main reason to have finger screens installed
it is to keep bugs,and debris from your Gas out of the system more than removing shellac/residual from the fuel/fiberglass system of fuel tanks
excellent post,it brings something up that should be of major concern to anyone not having or using finger screens
So far, I have made and installed a wiring harness from the tail to the panel for the trim and strobe. I cut a section out of each sponson and removed the landing gear for proper drilling. Replacing the foam and glass should be easy, I rebuilt 3 Vettes years ago. My dad and I also fabricated and installed a new more streamlined front end for his motorhome. The original was damaged in an accident, and the original company was out of business. We used glass and foam purchased from Aircraft Spruce.