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aux fuel return

1960 Beech Debonair. My left aux tank is not feeding return fuel to my left main tank. Is this a common problem ? What are some things I should tell my mechanic to check ?

Model: Debonair 35-A33
Aircraft Serial Number: cd-178
Posted 9/8/2021 - 8 months ago
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The aux tanks (10 gallon each in the box-section of the wing, just outboard of each main gear) should feed equally to the engine, and the return fuel from both should return to the left main. If you have no return fuel to the left:

Is it returning to the right? Or is there no return, period?

If returning to the right, you have a defective fuel selector, likely in concert with a plugged fuel return to the left.

If no return period, it must be running awful rich, likely in concert with a plugged return to the left.

The plugging, if only affecting the aux and not when feeding the left main, it is in the fuel selector or the short line that connects return fuel from the selector to a 'tee' in the left sidewall just forward of the selector.

Mike
ABS Tech Advisor

Posted 9/8/2021 - 8 months ago
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Thanks for the response Mike. To be honest, I haven’t checked to see if it’s returning to the right. I got a trip on Saturday, I’ll check it them. Thanks for the info…

Posted 9/9/2021 - 8 months ago
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I would recommend this gets addressed before further flight. If there is something amiss with the fuel delivery system, we don't want to read about you in an NTSB report.

Station one person inside the cabin and one at each main filler port; fuel is returned to the main tanks at the outboard end, high in the cell; when it is returning, there are noticeable waves and bubbles that appear to flow. Select left main tank, mixture lean, throttle open, and turn on aux fuel pump; there should be return present at left main only. Repeat for right main and there should be return to right main only. Repeat for aux tanks, and again it should return left main only.

Posted 9/9/2021 - 8 months ago
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MIke,
Any answers as yet? I had a similar issue with my 1960 Deb. Left aux drained fine, right (passenger side) aux tank would not drain. My A&P assessed the check valves and the fuel lines. No joy. Sold to another pilot. Was having his A&P evaluate. I will text him to see if any resolution. Good luck.

Posted 9/18/2021 - 8 months ago
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The most common issue for AUX tank not drawing together is the fuel cap seals and/or caps not fitting properly.
As Mike stated make sure vent system is clear.

Bob Ripley
ABS Technical Advisor

Posted 9/20/2021 - 7 months ago
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aux fuel return