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QB Wings, Fuel Sender Fitment

bkervaski

Hellloooooooo!
Testing
Any tips on fitting the fuel senders on the QB wings? I thought it would be as easy as bending the rods appropriately and plugging them in but you have to tweak to fit, problem is, can't see anything really to tweak and my bore-scope won't fit through the holes.
 
I know I had to tweak a lot on my SB tanks and they were still open, can't imagine doing on QB tanks that are all sealed up..
 
Measure the height of the tank at the location where the float will contact top and bottom, and the vertical relationship of the sender flange to those points.
Transfer the measurements to a piece of cardboard (I.E. make a scale sized simulation of the cross section of the tank).
Position the sender on the edge of the cardboard and swing the arm through its range.
Adjust as needed.
 
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Alternatively, measure the ohm reading from the sender for fully empty and also the full position. Use the measurement that has given in the plans for bending and install it with a string attached to the arm that you can lift it up thru one of the screw holes, install it with the string attached. When it is at fully empty position read the ohm to verify, then pull it up with the string to read again and most importantly to check to see if there is any interference.

You most like will end up dealing to tweak it for the interference than reading. The measurement in the plan is pretty darn close.
 
Well, got it done.

One of them is still tapping the skin if I pull on my testing string, it has about a 1/32nd clearance at rest.

Is that 1/16th top and bottom clearance critical? I'm not really seeing how to get the gap on one side without affecting the gap on the other .. perhaps a small third bend?

But other than that, I get 30-248 on the meter on the R tank and 30-245 on the L tank on the meter. Not sure how critical that 3 ohms is .. assuming there is an EFIS calibration in my future ;)

Thoughts?
 
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Note that the arc showing the float travel on p 18-07 is in error. The two arcs I added are centered on the pivot point, so the float actually comes very close to touching the rib. In my case it did hit the rib and caused some rework. On slow build wings you'd probably catch it before closing up

2cdxwjl.jpg
 
I measured resistance "full" and resistance "empty". Made the bends per the plans and installed them with a couple of screws snugged up.

Then, I measured the resistance again with tank right side up - "empty", and upside down, "full".

Worked like a charm.

Just to make sure the float didn't hang up, I used double sided tape and my iPhone on video record. Used a flashlight to provide some light, and flopped the tank back and forth. No problem.

This was on my RV-8. YMMV.
 
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Could it be that the thickness of the proseal after removing the supplied gasket is a critical measurement. I made sure I had a flange seal thickness that was reasonably generous. Didn't have issues with rib interference.
 
Could it be that the thickness of the proseal after removing the supplied gasket is a critical measurement. I made sure I had a flange seal thickness that was reasonably generous. Didn't have issues with rib interference.

I don't think so. I had to add "V" bends to both my sender arms to get clearance from the rib: on the second go-around I even shortened one of the arms a bit but still had some interference. And I did the same with "generous" sealant. Of course, when fitting the arm, it's hard to get "just right" standoff since sealant is the last thing done. I wanted to be SURE than when I seated the sender with sealant I would be good to go: this is more critical with QB tanks (my case) than if the arm is fitted before closing up the tank.

I had another issue as well: the right tank sender was a little "stiff" - didn't want to freely move up/down with gravity alone. I futzed with it a bit and finally ordered another from Summit Racing which was fine.
 
I wonder how many people have had leaks with the provided gasket. I used the gasket on my old plane and for 8 years that I owned it, there was no issues. I know the cork gasket has caused issues but not aware of any issues with the rubber gasket.
 
For people reviewing this older thread, note that we published an updated Section 18 for the RV-14 KAI.

https://www.vansaircraft.com/service-information-and-revisions/18-2/

The bending instructions and template for the IE-F385B Fuel Level Sender float wire created a geometry that allowed interference between the float wire and the nearest T-1004-L Fuel Tank Interior Rib. A new float wire geometry has been created that will eliminate this interference.
 
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