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Long range tanks (problem)

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Gary:
Any Helio owners with long range tanks aware of issues? I’ve heard the install of the tank can cause a structural weakness and possibly poorly rigged ailerons. Any truth to this?

Louis:
What do you mean by long range tank ?  Are we reffering to the 120 gallons wing compare to a 60 gallons wing ?

As you see, i am referring not to a 60 gallons tank vs a 120, but a 60 gallons wing

There is more difference to a 120g wing than juste the installation of two outside inside tank.  There is structural change as the length of the pickup of the wing spar near the fuselage.  They are considerably longer.

A 120 gallons wing works as well as a 60 gallons wing for flying.  Besides the weight of it, empty or not, naturally.

If we are talking about a inside the cabin long range tank,  the T valve  on the roof on the tube between the two tank can be changer to a cross ( 4 way )  fitting to allow the connection of the inside the cabin long range tank.  With a a one way valve.   Then you are filling both tanks at the same time.  But you need a pump.  The installation drawing on the U10 manual looks like if the fuel is gravity feeded towards the floor

Louis

Louis:
Installation of a ferry tank

Gary:
Thanks Louis for the info. Yes I am referring to the 60 per wing rancher than the typical 30 gallon per wing. I assumed the extended 60 wing would require the removal of a rib or two. The only two Helios that I am aware losing a wing or a breakup both had the 120 gallon long range tanks

Doug Johnson:
Gary,
At least one other person believes there is a correlation between wing separations and the 120 gal long range fuel tanks. Personally I don't believe the 'Long Range Fuel Tanks' contributed to any of the wing separation, primarily because of structural changes to the wing mentioned by Louis when long range fuel tanks are installed.

The wings on the stallion and the twin Helio which use the same wing and the same attach bolts both have 55 gal wing tip tanks. An identical wing to the a/c that had wing separations, is used with the STCed XLR fuel tanks there are only 3 of those that I know of, they have 6 fuel tanks with 2 placed in the farthest out board bay and the experimental turbine H-15 has airfoil shaped wing tip tanks that actually make the wing 18 inches longer also uses an identical wing.
 
On the H7/800 wing after c/n H2 the wing attach on the top is changed to a bolt similar to the bottom and the take off weight is increased to 4000 lbs, landing weight remains at 3800 lbs this was done by basically incorporating the 3800 lb upgross STC by increasing the wall thickness of the diagonals in the upper and lower bays of the crashcage/fuselage.
 
My understanding is that fuel tanks are generally placed in the wing for a couple reason foremost is that it is doesn't take up space in the fuselage that could be used in other ways and that it allow the fuel to be placed closer to the CG and a wing location doesn't place as much load stress on the aircrafts airframe.

There were more than 2 a/c that had wing failures. Turbulence was also connected to most of the aircraft that had wing failures a couple were connected to G-load from maneuvering. At least one of the a/c that had a wing failure had recently had the wings changed or removed and replaced, which may have contributed to the failure

I had a long somewhat confidential conversation with the now deceased Factory Engineer Robert Casebeer about this. I believe he hinted at something. He explained that the Wing attach bolts are 0 tolerance, and the machining of the fittings that the bolts go through was contracted out a vendor. The holes were first drilled then reamed to 0 tolerance. The vendor had a problem with this reaming and some of the holes had scratches deep in the holes and of course during the inspection process these were detected and rejected, I believe He was telling me these scratches could have led to corrosion and stress cracks in the scratches.

Robert didn't say so but later thinking about it the Factory may have suspected that not all were caught during the inspection process, but this would never have been admitted.

I assume the magnaflux process that is now in place would catch this.

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