Install Float Fuel Sending Units in QB Wings?

[ERushing]

I'm getting ready to install the float fuel senders in my QB Wings. Has anyone else done this? Any suggestions?

Instructions state that the float needs a maximum clearance of 1/8" from top and bottom of tank. Also states that floats should be centered between the vent line and the aft upper tank stiffener. Unless I can figure out how to get a camera in there, I don't see how I can accomplish any of this except via blind luck.

Your suggestions would be very welcome. Thanks!

[rocketman1988]

Make SURE that you check the B nut on the vent fitting inside the tank. Some have found it to be loose on the QB tanks...Mine wasn't but I checked it before installing the Capacitive sending units that I got from GRT...

[Ironflight]

Just bend the float wire per the template in the plans and you'll be fine - at least that has been my experience. It is very common for people to miss the little bend at the very end of the wire - the end that goes into the sending unit. If you forget this, the float wire will spin on the sending unit, and never give you a good reading.


Paul

[ERushing]

Thanks Paul! You're absolutely right! Looking at the plans now, I would have missed that.

Any thanks for the tip, Bob. i will definitely check that nut.

[Bill.Peyton]

As Paul recommends, bend it per the plans, in addition, remove the tank and put an ohmmeter on it and carefully turn the tank upside down and right side up to verify its not hitting the vent line and hanging up. Also, don't be so concerned that it hits the top. In fact, make sure it barely touches the top and hits both the top and bottom of the tank. Due to the dihedral and length of the tank, in actual use, you will not be able to get an indication until 5-10 gallons have been exhausted from the tank, so it's important that it barely touches the top of the tank and starts to drop immediately as the fuel is consumed. The actual resistance of the pot will be calibrated out during your efis setup.

[RV3bpilot]

If installing the sender unites to wings that are on the bench and not on the aircraft you can check the full and empty readings by hooking up a gauge and roll the tank upside down for full reading and upside up for empty reading. At least you will know that they are working. You won't know how accurate they are unless you add fuel one gallon at a time. But at least you can see if they work..

[JackinMichigan]

My instructions show a chart for the RV-3, then the RV 4 thru 9. No mention of the RV-10. I assume that I just use the dimensions for the RV-9, but just checking here to make sure..

Jack in Michigan

[ERushing]

Hi Jack,

Check Page 18-7 of the plans. Figure 1 gives the general dimensions for bending the wire. Like the included instructions say, don't forget the little right angle bend that goes into the sender!!

[JackinMichigan]

I did find the specific instructions for the RV-10 after I posted. However, I now have another question.

By following the instructions supplied with the 8.5 x 11 paperwork (not the plans) it tells me how to bend the tang that goes into the sending unit.

The float is offset with most of it to one side. If I follow those bend instructions, I put the larger side towards the vent line, encouraging a contact. I want to reverse the tang putting the float further away from the vent line. I see no issue, but looking for concurrence.

[ERushing]

The float is reversible. I ended up cutting an access plate in the rear baffle so it ended up being a lot easier to adjust the wire for clearance. But, before that, I was able to put a flashlight (with a string attached) through the float plate hole and look through one of the holes (vent, drain, etc) and get the wire adjusted so it didn't hit the vent line or any internal structure. Several cycles of attach, check, take apart, bend, repeat.

Good luck!