Replies to This Discussion

Permalink Reply by Tracy Buttles on April 20, 2012 at 8:37am

You might have to solder on some vent tubes that will stick into the airflow ,they might take a little tweeking to get them into the airflow that will balance the pressure better to get them to flow even ,not uncommon ,my old 150 cessna did the same thing!

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Permalink Reply by Bob McDonald on April 20, 2012 at 9:56pm

My CH750 does the same thing. No idea why? I even installed different fuel caps and changed them from side to side.. no real understanding as to why this happens.

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Permalink Reply by Thomas Richardson on April 21, 2012 at 8:37am

Thanks for the help eveyone.

Tom

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Permalink Reply by Jonathan Porter on April 22, 2012 at 5:01pm

lots of reasons, and all seem to have the same....

a) fuel lines are different lengths... thus different pressures.

b) air flow over the wings is different... thus changing the pressure at the cap

c) The aviation gods like us.... so they send us things to make us think

I am not sure if you run one side dry if the other will flow without sucking air, however, the easy solution is to put a tank selector in... then you choose, you monitor - but you also have to take the responsibility...see c) above!

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Permalink Reply by Dan Wilde on April 29, 2012 at 9:10pm

I had to make a precautionary landing to get fuel when my passenger side tank was showing empty while the other tank was full.  Scared the crap out of me.  I had lots of fuel in the other tank but it did not appear to be flowing.  As mentioned above I installed simple shut off valves on each tank so if one tank gets low I can turn that tank off and force flow from the full tank.  Works great and relieves pilot anxiety.

 

Quality Planes told me the other tank would eventually feed fuel and you would not run out but I opted to make sure I had fuel flow.

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Permalink Reply by Chumphol Sirinavin on April 29, 2012 at 10:06pm

I plan to use one of these valves at each wing roof to control wing tank fuel. Fuel selectors can have positions not in line with my psychomotor.

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Permalink Reply by Chris Aysen on April 30, 2012 at 10:12am

Thomas - You might notice that letting the tanks sit overnight that they level off with each other. After experiencing all this myself I have come to the same theory as Jonathan.

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Permalink Reply by david shrader on August 9, 2013 at 7:55pm

I'm not sure if this means anything or not but we have accumulated 7.3 hrs. so far with no fuel imbalance. After we herd that fuel imbalance can occur we were keenly aware of the fuel in both tanks and have watched it closely (longest flt. 1.7). The only thing that I can come up with that could be causing the fuel to flow evenly on our 701 is the vented header tank, the fuel lines are different lengths, and the vented caps are stock, we ran 3/8" hard line's from the wing tanks to shutoff valve to header tank to the firewall. Since the fuel is dropping evenly on both sides and our fuel system is not that different than any other 701 I am concluding the 3gal. header tank made a difference.
Dave

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Permalink Reply by David Pippert on October 13, 2013 at 12:12pm

Hey Tom !
I too have experienced that same fuel level thing. And what I conclude is it is great. The low tank empties more completely then if I were able to control it. As soon as the low tank sucks air the flow instantly starts on the other tank and I now know that that tank is empty ! I fly my 701 long range up to Alaska in the summer. With a total of 40 gallons up in the wings. The fuel selector is inboard and outboard. I fly the outboards down first. Thanks David

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Permalink Reply by Normand Lambert on October 15, 2013 at 8:32am

Hi Thomas,

Got the same thing on my 701. Passenger side empties faster too. I went as far as shut it down to see if I would starve the engine. Not so ! The engine continued to run like a champ on the pilot side tank only as if nothing happened. I was told that this happens frequently. Looks like it's not a concern but still is strange. For me, I don't care anymore since I know both tank will run dry before the engine quits !

Regards,

Norm

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