Fuel  flow problem

[Ron Belliveau(Guest)]

Transport Canada request a fuel flow test. They require you to prop up the aircraft in a 15 degree angle ( to simulate climb out) and require a 150% flow rate of the engine max burn rate. Our 360 engines require (with the 150%) 28 gph . A fuel flow test showed only 18.75 gph. After much checking and testing we found that by removing the floscan meter (last item in the line to carb.) we had a 33.75 gph flow. One would be lead to believe that there was a problem with the Floscan but we have two aircraft with each a floscan and the same results. 18.75 gph will not keep the 360 running at full power . What are we to do next?

 

[dynonsupport]

First, what is measuring the flow rate during this test? Next, is the engine on during the test? Finally, what is pumping the fuel during the test? You probably wouldn't expect to see normal flow rates in a simulated situation that isn't representative of the pressures that the fuel would be under in normal circumstances.

For reference, at 30 gph the pressure drop across the FloScan sender that we provide is specified at just 1.2 psi.

 

[Ron Belliveau(Guest)]

Re: Fuel  flow problem

The test required by Transport Canada, is a timed test into a measured volume. We are clocking the time required for 60 oz. Our requirements , for 28 gpm , is 60 oz. in 60 seconds. Our system is gravity fed and before the flow meter (floscan) it took 50 seconds to fill 60 oz. With the floscan installed and it draining in a funnel at carb level ( as all test were) it took 90 seconds . We are not concerned with the reading on the flow meter, ( although it is quite close) the floscan reading has nothing to do with this test, only it's restriction. We are not professionals, and are still learning . Our goal is to be safe from the first flight on, not to have an engine quite on the first climbout! Lastly the engine has yet to be started.
Thanks Ron

 

[dynonsupport]

Ron,
As we mentioned in the last post, at 30 GPH the floscan has a 1.2 PSI drop.

If you're gravity fed, a 48" head of fuel is only about 1.3 PSI. It's no wonder that you can only flow 18 GPH through the FloScan.

Unfortunatley it looks like you'll either need a fuel pump to pass this test, or you'll need to find a lower restriction fuel flow sender. We only sell the 201B, but any FloScan unit will work with our EMS, as well as probably any other sender you could find.