REFLECTOR: Good Friday Landing

[Ron Brown]

I'm confused.

It would be difficult to install the pump below the sump outlet, but not so difficult to mount it level with the SUMP.

I don't see a problem mounting the pump unless it was up above the sump, like level with the CS spar or above.

I have an RG and my pump is on the floor in front of the sump tank, I don't have any problems.  Many of the pumps are mounted on the firewall.  The engine driven pump is above the sump outlet and it is sucking fuel out of the bottom of the sump tank - through a whole bunch of tubing and a check valve in my case.  Works fine.

Perhaps 1/2" line would help in Dave's situation.  I doubt Dave's pumps are above the top of the Sump Tank???

Ronnie
  ----- Original Message ----- 
  From: bdtopp at comcast.net 
  To: Velocity Aircraft Owners and Builders list 
  Sent: Wednesday, April 06, 2005 9:31 AM
  Subject: RE: REFLECTOR: Good Friday Landing


  Randy,
      Thanks for the explanation.  I thought there must be a difference.  Doesn't this mean that all FG models could have the fuel starvation problem that Dave experienced?  Obviously nobody is since we haven't heard of this before (or have we?).  It doesn't make sense that moving the fuel pumps is going to solve Dave's problem since all FG models have the elec fuel pump equal to or higher than the sump tank and the mech fuel pump is always higher.  Has anybody besides Dave (and Sid on Starduster) experienced fuel starvation do to the location of fuel pumps?

  Bruce Topp
  N125TP XL-FG 

    -------------- Original message -------------- 

    Bruce,

      On the RG models, the slim sump mounts on the forward side of the firewall, just under the spar. There is room underneath, unlike on the FG.

     

    Randy Wharton

    N248RB XL/RG

     


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    From: reflector-bounces at tvbf.org [mailto:reflector-bounces at tvbf.org] On Behalf Of bdtopp at comcast.net
    Sent: Wednesday, April 06, 2005 8:39 AM
    To: Velocity Aircraft Owners and Builders list; Velocity Aircraft Owners and Builders list
    Subject: Re: REFLECTOR: Good Friday Landing

     

    Dave,

       Excellent job on your emergency landing!  You mentioned that your fuel pumps (mech & elec) were located above the sump tank.  Maybe I am missing something here, but, won't the mech. fuel pump always be above the sump tank?  At best, the elec. fuel pump can be mounted even with the bottom of the sump tank but not below it.  Maybe this is a difference between the retract and fixed gear model sump tanks.  I have the fixed gear.  How do you plan on moving fuel pumps below sump tank?

     

    Bruce Topp

     

      -------------- Original message -------------- 
      On my Starduster with a homebuilt EFI, I had a similar event occur within the first few hours of flying on a hot Summer day. Same cause... pulling auto fuel uphill about 8 inches. I subsequently relocated my pumps (main and back-up) BELOW the lowest part of the fuel tank and have had no more problems (four years now). What's worse, I had warning signs that all was not right. First was that I could see bubbles in the clear plastic fuel line at the input of the pump and I simply thought, "..now why are all those bubbles there?.. how could I have an air leak??" and went on to other things. Second was the pump was howling (cavation I realized later) and I wondered why a new pump was so noisy and went on to other things. Dumb? Yes, but I was in new territory (for me) and had to learn by experience. Further, at the begi! nning, I had no back-up f! uel system which I now have. 

      Sid Knox
      Oklahoma

      Velocity N199RS
      Starduster N666SK
      KR2 N24TC
      W7QJQ

      > Our conclusion is fuel starvation caused the failure. I have talked to many
      > experts including our own Scot Baker and this is our finding. My fuel
      > pumps were located above the sump tank requiring the pumps to suck uphill. 
      > My supply line to the pumps was 3/8 pipe and I am going to 1/2 inch. I had
      > the old vent system with a 1/4 vent tube and no check valve. Will
      > correcting these things prevent a future problem? I will find out. 



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