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  #1  
Old 09-02-2017, 07:43 AM
T.O.Craig T.O.Craig is offline
 
Join Date: Feb 2006
Posts: 150
Default Fuel flow testing

Howdy to all,
I'm getting close to having a completed RV 10. It is powered by a IO540. One of the tests I will conduct will be a fuel flow test. I'm looking for any suggestions on how to accomplish this ....
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RV-10/Empennage/Wings/QB Fuselage/Wiring/Doors done finally, Cowling done. Stein panel complete, and connecting all those wires :-))Thousand Oaks, Ca. Dues paid for 2017
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  #2  
Old 09-02-2017, 08:41 AM
Sandrews Sandrews is offline
 
Join Date: May 2017
Location: Denver CO
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Can't help with the question but interested as well.
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  #3  
Old 09-02-2017, 10:20 AM
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Carl Froehlich Carl Froehlich is offline
 
Join Date: Dec 2007
Location: Dogwood Airpark (VA42)
Posts: 1,060
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Here is how I do it:
- After I build the tanks I let them sit on the bench for a few weeks with a 5-10 gallons of 100LL in it. I rotate the tanks to different position from time to time. The objectives are to find any weeping rivets and to flush the tank. I drain the fuel via a hose connected to the sump through a see through auto fuel filter back into 5 gal jugs. This is repeated until I'm sure no junk in the tank.
- With the tanks on the wings, wings mounted and fuel system plumbed, I replace the AirFlow Performce fuel filter with another see through auto filter. I disconnect the fuel line on the engine side of the firewall and connect a hose to a a five gallon tank.
- With the tanks empty, proceed with your EFIS or EMS fuel level calibration proceedure (most do a 2 gallon at a time add to each tank).
- After you hit the top of the fuel sender travel, use the planes fuel pump to pump each tank to the series of 5 gallon jugs. Measure the fuel flow and convert to GPH.

This process calibrates the fuel level senders, flushes the fuel system, and verifies the pump can deliver much more than the engine can use.

Carl
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  #4  
Old 09-02-2017, 11:07 AM
Kyle Boatright Kyle Boatright is online now
 
Join Date: Aug 2005
Location: Atlanta, GA
Posts: 2,863
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Quote:
Originally Posted by Carl Froehlich View Post
Here is how I do it:
- After I build the tanks I let them sit on the bench for a few weeks with a 5-10 gallons of 100LL in it. I rotate the tanks to different position from time to time. The objectives are to find any weeping rivets and to flush the tank. I drain the fuel via a hose connected to the sump through a see through auto fuel filter back into 5 gal jugs. This is repeated until I'm sure no junk in the tank.
- With the tanks on the wings, wings mounted and fuel system plumbed, I replace the AirFlow Performce fuel filter with another see through auto filter. I disconnect the fuel line on the engine side of the firewall and connect a hose to a a five gallon tank.
- With the tanks empty, proceed with your EFIS or EMS fuel level calibration proceedure (most do a 2 gallon at a time add to each tank).
- After you hit the top of the fuel sender travel, use the planes fuel pump to pump each tank to the series of 5 gallon jugs. Measure the fuel flow and convert to GPH.

This process calibrates the fuel level senders, flushes the fuel system, and verifies the pump can deliver much more than the engine can use.

Carl

Good advice. The other thing that is important to me is to elevate the nose while performing the flow test. You accomplish that by either putting the nose wheel on a stand or maybe by ratcheting down the tail. Doing the test under those conditions will verify adequate flow at a climb attitude.
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2001 RV-6 N46KB
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  #5  
Old 09-02-2017, 11:17 AM
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Toobuilder Toobuilder is offline
 
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Location: Mojave
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In addition to the nose up attitude, you will want the outlet of the hose/line to be the same height as the servo inlet/float bowl. Running a hose all the way to a bucket on the floor takes advantage of the siphon effect and can give a false positive indication of fuel flow. Probably overkill, but I like to see every chance for the system to fail in the hangar rather than the initial climb.
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  #6  
Old 09-02-2017, 01:24 PM
Tom Martin Tom Martin is offline
 
Join Date: Jan 2005
Location: Ontario, Canada
Posts: 1,288
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Just did the fuel flow test on the 14 today. I disconnect the fuel line at the servo, and attach a piece of 3/8" fuel line and fitting that goes to a large graduated cylinder. As Mike noted it is important to simulate actual conditions. Run the electric pump long enoug to get a steady flow then stop, note fuel amount and run for a set time or until container is full. Note amount difference vs time running and calculate fuel flow per hour. Do this for each tank
Dump test fuel into your lawn mower etc.
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  #7  
Old 09-02-2017, 02:36 PM
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snopercod snopercod is offline
 
Join Date: Aug 2016
Location: Asheville, NC
Posts: 804
Default Mr. Funnel

One of these Mr. Funnel fuel filter funnels comes in real handy when flushing out your fuel system. It filters out water and debris, and you can see what you caught. I use one of these when de-fueling into gas cans and re-fueling from the gas cans back into the airplane. (I actually use the bigger one with two filters, but that's probably overkill.)
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  #8  
Old 09-03-2017, 07:32 AM
T.O.Craig T.O.Craig is offline
 
Join Date: Feb 2006
Posts: 150
Default A couple questions

Thanks for all the great input. I have a question as to where to disconnect the fuel line in the engine compartment. If I understand correctly, Carl states to disconnect the fuel line at the firewall before the mechanical (engine driven pump) and conduct the test from that location. Am I correct in assuming that?

Tom stated he likes to disconnect at the servo. To me that almost seems like a better idea because it is then flowing through the engine driven pump also, where there could be some additional flow restriction.

This is all good info. What flows are we getting when we do the calculations??
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Craig Rufi
RV-10/Empennage/Wings/QB Fuselage/Wiring/Doors done finally, Cowling done. Stein panel complete, and connecting all those wires :-))Thousand Oaks, Ca. Dues paid for 2017
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  #9  
Old 09-03-2017, 11:24 AM
BillL BillL is offline
 
Join Date: Sep 2007
Location: Central IL
Posts: 3,941
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I honestly don't see much benefit to a gravitational test.

Suggestions:

1. air pressure test from wing root to servo, Just to ensure there are no risk of leaks. None. Zero. Absolutely none. If your lottery tickets always pay off, skip this step.
2. Max fuel flow at max pressure test from tank out past the red cube. The red cube in there allows one to set the flow rate and record pressure. Ensure there are no bubbles in the discharge. A clear section before a restriction valve is needed.

a. Initial run (purge) to a waste container. Test fluids will be in the pump
b. Run each tank dry to evaluate unusable at various attitudes.

These will ensure, no leaks, proper suction under flow conditions, and the back pressure allows real life flow in the pump circuit. It will likely yield less usable than a gravitational test, but not by much on the ground.
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  #10  
Old 09-05-2017, 09:22 AM
rvdave rvdave is offline
 
Join Date: Jun 2005
Posts: 236
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Getting ready to pressurize from fuel servo back to wing root testing for leaks. Should there be any concern about pressurizing backwards through fuel pump? Don't want to blow a diaphragm or whatever the configuration is in there.
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