Fuel flow test

apkp777 · #1 05-28-2010, 09:07 PM

I did a fuel flow test today (removed fuel line from carb). I measured 26.6 gph. This is a stock set up (Van's fuel pump, gasocolator and lines as per the drawings.

Does anyone have numbers to compare?

robertahegy · #2 05-29-2010, 06:56 AM

With the Van's electric pump I got about 42 GPH on my 7A. The pump is rated at 30 GPH at 4 psi, so at 0 psi (open fuel line) flow will be higher than rated. Standard Van's fuel system configuration except I used 3/8" flexible fuel lines from the sides of the fuselage to the fuel valve. I had short AL lines through the fuselage rubber grommet to the tanks. I used this test on every annual to ensure the pump was operating properly and there were no clogs or restrictions. Plane should be level when test is performed to elliminate the losses due to lifting the fuel.

I had heard of the fuel pump being plugged with metal shards from building processes and wanted to be sure I did not encounter that problem. I did experience these shards getting caught in the fuel tank drains and flushed several times before finally clearing them out. I had QB tanks.

Roberta

vlittle · #3 05-29-2010, 07:40 AM

Quote:

Originally Posted by apkp777

I did a fuel flow test today (removed fuel line from carb). I measured 26.6 gph. This is a stock set up (Van's fuel pump, gasocolator and lines as per the drawings.

Does anyone have numbers to compare?

I got 25.1/25.6 gph on my 9A, with the carb fuel line elevated 16" above the carb, representing a deck angle of 22.5 degrees (12.5 degrees best angle of climb + 10 degrees AOA).

http://www.vx-aviation.com/rv-9a/pho...126_2671_1.jpg

Vern

noelf · #4 05-29-2010, 08:32 AM

...my configuration is: Tank---Selector Valve---Electric fuel pump---gascolator---fuel flow transducer---carburetor. Fuel flow was measured at the carb.
1. 3 gal fuel in each tank to minimize head pressure.
2. Three point attitude = 32.4 GPH
3. Tail resting on ground = 31.0 GPH

lostpilot28 · #5 05-29-2010, 04:33 PM

Quote:

Originally Posted by noelf

...my configuration is: Tank---Selector Valve---Electric fuel pump---gascolator---fuel flow transducer---carburetor. Fuel flow was measured at the carb.

This was my fuel line routing exactly, but my airplane is a -7A. I just looked at my notes and I got 30 gph running the electric pump only.

apkp777 · #6 05-29-2010, 04:41 PM

It sounds like my numbers are "in the ball park"! Engine ran great (first run) today.

alpinelakespilot2000 · #7 10-25-2011, 11:16 AM

Quote:

Originally Posted by robertahegy

Plane should be level when test is performed to elliminate the losses due to lifting the fuel.

Everything I've read suggests the plane should be in climb attitude (maybe even the best angle of climb) when the fuel flow test is being made. Is that the case? If so/if not, how high will I need to get the mains above the tailwheel to perform a useful test.

alpinelakespilot2000 · #8 02-28-2012, 03:09 PM

Quote:

Originally Posted by alpinelakespilot2000

Everything I've read suggests the plane should be in climb attitude (maybe even the best angle of climb) when the fuel flow test is being made. Is that the case? If so/if not, how high will I need to get the mains above the tailwheel to perform a useful test.

Vern seems to have a rationale for why he chose to do what he did a few posts above, but does anyone know whether there is a "proper" attitude for the a/c during this test? I've looked in AC43.13 and in the FAA flight test circular but couldn't find any guidance on the appropriate attitude at which to do the flow test. Has anyone gotten an answer from Van's on this?