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Pressure testing lines

Ace

Member
I see nowhere in the plans to test the brake and/or fuel lines for leaks. Is anybody doing this? If so, what method are you using? vacuum? pressure ? thanks ,
Ace

rv10
40567
 
Ace said:
I see nowhere in the plans to test the brake and/or fuel lines for leaks. Is anybody doing this? If so, what method are you using? vacuum? pressure ? thanks ,
Ace

rv10
40567
I think you will find that most folks step on the brakes and fix what leaks

For fuel, turn on your pump and see what leaks. On the fuel, you can cap off the line at the engine and turn on the pump.

Low tech, but works.
Best,
 
Ace said:
I see nowhere in the plans to test the brake and/or fuel lines for leaks. Is anybody doing this? If so, what method are you using? vacuum? pressure ? thanks ,
Ace

I had the local A&P test mine. Cost me 10 dollars total for all my oil and fuel lines, he even remade one fitting. Getting to know the local A&P works out very well for both parties. They usually have some good advice on engines and you can teach them some metal working tricks. If they know they can come by your hanger and get the odd bolt of rivet, they will probably be quite generous when you need a hand.
 
I have a hose testing rig I built out of a hydraulic screw jack. If anyone wants to come to Cartersville, GA on a weekend, we can test (or destroy) hoses until youre heart is content.

Since I built my own hoses, I tested them to 150% of the value I expect the hoses to see in use.

The interesting issue (for me, anyway) was "Where to stop with the pressure testing?". For instance, if an oil hose might see 100 psi in service, but the hose is rated for 1,000 PSI, do you test to 150 PSI or to 1,000 PSI? Hypothetically, the hose end fitting might hang on just fine to 500 lbs, but might blow off at 501 PSI. Does that really matter to me in my 100 PSI application???
 
Pressure testing the fuel system, not just the hoses.

Before buttoning up the fuel and brake lines with covers, hoses and the forward fuselage , I wanted to check my entire system for leaks. I am less worried about the hoses as they were tested by the supplier, http://www.aircraftspecialty.com/

I am much more concerned about the fittings connecting them all together.

I have 2 electric fuel pumps, fuel filters and a duplex Andair fuel valve. Is it advisable to pressure test this as a system (not the tanks) from wing root to firewall. The working pressure will be 35 PSI.

If I do pressure test them, what is considered acceptable? An obvious leak is easily recognizable. What pressure should I test it to? How long should it be tested for and what, if any is an acceptable pressure loss over x hours.

Is the Andair fuel valve able to be pressure tested? I just sent them an email.

Thank you.
 
Before buttoning up the fuel and brake lines with covers, hoses and the forward fuselage , I wanted to check my entire system for leaks. I am less worried about the hoses as they were tested by the supplier, http://www.aircraftspecialty.com/

I am much more concerned about the fittings connecting them all together.

I have 2 electric fuel pumps, fuel filters and a duplex Andair fuel valve. Is it advisable to pressure test this as a system (not the tanks) from wing root to firewall. The working pressure will be 35 PSI.

If I do pressure test them, what is considered acceptable? An obvious leak is easily recognizable. What pressure should I test it to? How long should it be tested for and what, if any is an acceptable pressure loss over x hours.

Is the Andair fuel valve able to be pressure tested? I just sent them an email.

Thank you.

If I were to go to that level of testing, I would plumb in a 1/4" NPT fitting and apply an air hose connection. Pump up the regulator to 50-60 PSI and use soapy water on each connection. Could also plumb valve soe that you could see if the rig holds the 50 PSI for a few minutes. A rapid drop in pressure points to a leak big enough to need addressing. When my servo was fresh back from O/H by AFP, at ICO, my fuel pressure would be 15 PSI one hour after engine shutdown; a pretty good indication that I had no leaks in my system.

Don't pressure test the valve, as it is not installed in a pressure environment. It is possible that it is not designed to handle any significant pressure, as it sits on the suction side.
 
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Is the Andair fuel valve able to be tested?

I applied shop air to the line that connects to the tank and capped the line at the mechanical fuel pump and checked for leaks with soapy water. Andair valve and AFP pump did not leak at 80 psi.
 
I put 120 psi on my hoses with my compressor and two AN4 x 1/4"MIP fittings. 4 times working pressure with no leaks seemed like enough safety margin. Could have gone higher but this is already above my air hose working pressure.

Use caution, a blown hose could cause some damage. Strap it down! ;)
 
Work

If i wanted to stress test my hoses i would bring them to work with me and have them listen to my boss for an hour. They still might leak, but at least i will have something to consul while flying.
 
Before buttoning up the fuel and brake lines with covers, hoses and the forward fuselage , I wanted to check my entire system for leaks. I am less worried about the hoses as they were tested by the supplier, http://www.aircraftspecialty.com/

I am much more concerned about the fittings connecting them all together.

I have 2 electric fuel pumps, fuel filters and a duplex Andair fuel valve. Is it advisable to pressure test this as a system (not the tanks) from wing root to firewall. The working pressure will be 35 PSI.

If I do pressure test them, what is considered acceptable? An obvious leak is easily recognizable. What pressure should I test it to? How long should it be tested for and what, if any is an acceptable pressure loss over x hours.

Is the Andair fuel valve able to be pressure tested? I just sent them an email.

Thank you.

I highly recommend testing the complete fuel system with air pressure. 30 psi is plenty to find leaks. The system volume is so low that the pressure will fall pretty fast. Beware of where you add the air. I used the left hand right bulkhead fitting on the fuse-to-tank and ended at the fitting on the spider. The fuel valve definitely included, but the servo is bypassed. Several local friends were convinced to do the test and each found a surprise. A real surprise. Sometimes a factory component that you would not have expected. I left my pressure on overnight, but each of us (all) who found a leak notice the pressure fall 5 psi in 20 min. It is nearly impossible to find a fuel suction leak by looking for dye. Fuel Selector is tested from each side and then to ensure it shuts off, that test does not take long. Finding a leak is a process of checking easy sections then narrowing down. Standard soapy leak detectors work well.

Don't try to flow the air backwards through the mechanical fuel pump (if you have one).
 
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Pressure testing fuel lines

Hello,

Andair got back to me and stated the fuel vales are pressure tested to 80 PSI. They can perform higher pressure testing but they would do that at the factory.

Pressure testing is going well. I set the pressure yesterday afternoon at 30 PSI. As of 11:30 AM today the PSI has dropped to 15 PSI. No soup bubbles detected but I will apply again today. Not happy about the drop, but wondering if this is acceptable? Probably not. The volume is so little that even just the expansion of the lines due to the pressure may have an impact on the pressure.

I am going to run some 100LL fuel through it and check the pumps, pressure regulator, check for leaks and also do a preliminary fuel flow. This will also clean out the lines.
 
Michael and others, we typically pressure test our (AS Flightlines, Aircraft Specialty and TS Flightlines) assemblies to 2000 psi. WAYYYY beyond what you'll see, but the hoses are rated at 3000 psi WP. In doing development for our version 3 hose ends (that we have been using for about 3 years now), I took them to 6500+ for -3 through -8 and 4500 for -10s. -12 were 3500. The -10 through -16 hoses are a different type of construction. Generally 2x the rated working pressures of the hoses, NOT the system pressures. So for instance an engine with mechanical injection will see +-30 psi----so 2000 is a bunch of safety margin.

Tom
 
Just me

It is just me, but testing hoses to high pressures is fine, but I would not test fuel or oil systems to high pressure in the airplane, even if everything is rated properly. I say this because if a hose or fitting fails in the airplane with high pressure, it could cause a lot of damage to the airplane. I think just testing a two times working pressure of each section should be sufficient. I don't think we are trying to proof pressure anything, just check for leaks. As Yogi Berra might have told me,”... if it leaks with air, it might not leak with fuel; if it is good with air, it still might leak with fuel. “ or something like that.
 
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Hello,

Andair got back to me and stated the fuel vales are pressure tested to 80 PSI. They can perform higher pressure testing but they would do that at the factory.

Pressure testing is going well. I set the pressure yesterday afternoon at 30 PSI. As of 11:30 AM today the PSI has dropped to 15 PSI. No soup bubbles detected but I will apply again today. Not happy about the drop, but wondering if this is acceptable? Probably not. The volume is so little that even just the expansion of the lines due to the pressure may have an impact on the pressure.

I am going to run some 100LL fuel through it and check the pumps, pressure regulator, check for leaks and also do a preliminary fuel flow. This will also clean out the lines.

You can narrow down. The pump/filter assembly has a lot of potential points. One friend had a pump leak and one in the filter housing. 30-15 overnight is a medium leak. We shorten the range of pieces being tested to isolate the section before trying to test dozens of connections.

An assortment of AN plugs and caps was very helpful. Just make sure your test apparatus is not doing the leaking - had that happen on another project .
 
Found 2 leaks at th AN fittings - steal fittings

Update.

Tom S, the hoses are great and not leaking.

Where I am having leaks is at the AN fitting joints. One joint that is leaking is on the firewall. It is a steel male bulkhead AN fitting to a steel AN Female fitting on lifetime braided SS, conductive coated teflon hoses. I bet it is just so hard that if I am able to tighten it enough, it will not leak. I will try some fuel lube on the threads to ease any tightening. They are really torqued down now but maybe a few more degrees of rotation will sela them. The pressure went from 40 PSI to 30 PSI in about 10 hours. That is how slow the leak is in about 8 feet of 3/8 fuel lines.

Th second leak is equally as small and is on the steel tube to the dual fuel pump manifold on my FlyEFII system. I am sensing a trend on the steel being harder to seal.

I will also try disassembling and assembling a few times as recommended. I did see a small continuous amount of bubbles at these two joints.
 
Michael---steel is alittle harder to seal than aluminum, especially with stainless hose ends. Torque specs on the higher range for steel fittings usually solves the problems. I use the flats method most of the time. In our pressure test cabinets, we found that you dont have to really crank down on the fittings to test---just snug and 1/8-1/4 turn---or about another flat. I generally use 2 stubby wrenches and snug them.

Tom
 
Voshan

You could try Voshans, or flange seals, on the steel fittings. These are soft aluminum inserts that goes between the B-nut and the hose/tube.
 
Closing the loop - Results

I thought I would close this loop and share my results.

After many days of leak-down testing of my fuel lines, I have concluded that some pressure drop in the lines over a prolonged period of time appears to be acceptable.

I wanted to pressure test them prior to adding other items in the fuselage that would make accessing the lines more difficult.
I tested from the wing root to the firewall and then the return line from the firewall back to the wing root. I am using FlyEFII and this system requires a return line. No pressure testing was done on the tanks. The pressure testing went as high at 55 PSI. The prefabricated lines were tested at the manufactures to 2,000 PSI. The Andair duplex 3/8 fuel valve can be tested up to 80 PSI according to Adair.

I pressure tested the complete system, one side at a time. A fast leak down is obvious and should be addressed. If the pressure drops from the test pressure to something closer to zero over 15 minutes or even 2 hours, this may be a problem as well.

I was able to get my lines to a test pressure of 35 PSI in the evening and in the AM, 8-12 hours later, only losing 2-4 PSI. When left it for days (5) it went from 35 PSI down to 20 PSI. For this slow of a leak on such a small amount of volume, I could not find any leaks using bubble and even Snopes leak fluid. Maybe the pressure dial was leaking. I could not find any leaks after many tests. I invited other builders to look and find a leak and they could not.

Cautiously optimistic, I moved on to actual fuel tests. I purchased 2-5 gallon cans and bought 5 gallons of 100LL. I fabricated 2 aluminum lines for the wing root fittings. each line would go to one of the cans. The firewall fitting were looped (supply looped to return) with no pressure regulator in the loop.

I repeatedly transferred the 5 gallons from one can to another (swapping after each transfer). No leaks were detected. Under 12 volts, I was able to transfer all 5 gallons in 6 minutes using 1.9 amps of power on the FLYEFII Pumps, one pump at a time. (50 GPH) I did this on both sides; left and right.

No leaks.

I then performed the same test with both pumps running at the same time. Transfer time went down and current more than doubled for about 5 amps.
Still no leaks

Happy with those results, I installed the FLYEFII pressure regulator on the firewall and connected the supply and return lines to it. I transferred fuel and set the pressure to 35 PSI. Results were positive. Many test runs provided consistent results.
No leaks, 5 gallons transferred in 8 minutes 30 seconds .59 GPM = 35.29 GPH At 12 volts the current draw was 4.97 with one pump running.

I did try running both pumps at the same time with the pressure regulator installed (simulating take-off/landing) and both pumps stalled. I looked at the power supply and the voltage was way down. I believe the power supply could not supply the demand.

This morning I hooked up a larger power supply (12 Volt car battery) and ran both pumps simultaneously. The transfer time was 4:45 seconds or 1.05 GPM or 63 GPH. No Leaks

Time to test the brake lines.
 
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