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Drippy 03-16-2017 06:07 PM

Fuel FLow Test
Just curious of anyone else as asked to perform a fuel flow test by FAA prior to inspection? I don't mind doing it and it actually sounds like a good idea but I didn't see a very much traffic about it on the board and was just curious if this specific to this inspector.

Almost flying, I hope:-).

Kyle Boatright 03-16-2017 06:15 PM

I did one on my RV-6, and will do one on the -10 when the time comes.

It is one of those things that is a VERY good idea. Fuel system problems are one of the leading causes for engine failures in experimental aircraft. So you want to do everything you can to minimize that possibility.

A successful flow test is one indication that your fuel system is working properly.

Drippy 03-16-2017 06:43 PM


Yes I agree it is a good idea.

What pitch attitude did you use with your RV8? Any thoughts on what you will use with the RV10?

Kyle Boatright 03-16-2017 06:49 PM

It has been a while since I tested the -6, but my recollection is of doing it in a three point attitude with the tail wheel in a slight depression.

With the -10, I'll probably find a way to prop the nose wheel up with the tail tie-down ring on or near the ground.

Drippy 03-16-2017 06:58 PM

AC90-89B calls it out at 5 degrees above the highest anticipated climb angle. Not really sure what that is?

Any of you flying RV10 guys have an number of max climb angle?



N427EF 03-16-2017 07:48 PM

Fuel flow test is a must
My DAR did not ask for a fuel flow test but I certainly wanted to know how well
my fuel system performs.
It is somewhat difficult to place your airplane in such a nose high attitude as to be 5 degrees above the highest anticipated angle of climb.
I pulled down the tail and then jacked up the nose wheel until the tail tie down ring touched the floor.
Additionally I placed the receiving gas can a couple feet higher than the fuel controller, simulating a very steep attitude.
The rest is straight forward, hit the boost pump for a number of minutes,
measure total gas pumped and calculate flow per hour.
Don't recall the precise flow on my 10 but it was around 50 GPH.

N661DJ 03-17-2017 04:55 AM

FF Test
I did a fuel flow test on my recently certified RV8, AEIO-390.
Aircraft in 3 point position, flop tube right tank, normal pick up left tank.
Boost pump ON.
Left and right tank were the same results. 1 gallon every 64 seconds= 56.25
gallons per hour.

vic syracuse 03-17-2017 07:14 AM

It's a GREAT idea. Let it run a while to get all of the junk out of the fuel system from the build.


FLY6 03-17-2017 07:24 AM

Fuel check
I second it is not just a good idea but necessary. I had to do one on my RV6 to complete my import to Canada. The numbers did not add up and when I investigated I found a blockage in the fuel line just before the electric fuel pump. No noticeable difference in flight by the previous pilot who is very experienced. The blockage was estimated at 90 percent. I am still amazed when I look at the picture that the plane would fly.
Well worth the time and easy to do.

rleffler 03-17-2017 07:32 AM

Fuel flow test data was one of the things that my FSDO inspector asked about. Also like, Vic mentioned, you'd be surprised at what may be in your fuel lines. So doing the test before first engine start will prevent future headaches.

It's pretty easy in a RV-10. Use a ratchet strap on the tail tie down to raise the nose to the appropriate angle.

As one who experienced a mechanical fuel pump failure on the first test, I highly recommend doing fuel flow testing. You want to ensure that the electric pump can push adequate amounts of fuel.


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