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Airworthiness Cert

JDA_BTR

Well Known Member
Seeing the light at the end of the tunnel, reading the good article at https://www.eaa.org/en/eaa/aviation...built-aircraft-certification-inspection-guide

It says "The engine should have been run for at least 1 hour. The run should have included operating in a nose high above stall attitude to ensure full fuel flow, and a full power run to verify and ensure maximum designed RPM is attained."

How in the world do you run it that way? I can see a full power run... But can't let it get too hot before it is broken in? And how do you run it at that position? I'm stumped....
 
Seeing the light at the end of the tunnel, reading the good article at https://www.eaa.org/en/eaa/aviation...built-aircraft-certification-inspection-guide

It says "The engine should have been run for at least 1 hour. The run should have included operating in a nose high above stall attitude to ensure full fuel flow, and a full power run to verify and ensure maximum designed RPM is attained."

How in the world do you run it that way? I can see a full power run... But can't let it get too hot before it is broken in? And how do you run it at that position? I'm stumped....
On my last plane which was A model, I had two friends hold the tail down while going full power for two minutes. I am not sure how you would do it on tail dragger other than the normal attitude with the tail down.

I guess alternatively, you can raise the mains up while the tail is down and only check the fuel flow rate (unplug the fuel line from servo and run the pump) and measure the fuel flow rate.
 
I ran my engine per the Lycoming specs before first flight which is a lot less than an hour.

You can do the fuel flow test like I and others have done. Get the plane in the correct attitude by holding down the tail and run the fuel pump with the fuel line disconnected at the throttle body. Have the fuel line empty into a five gallon container, all nicely grounded, and measure the fuel flow with the fuel flow meter.

You should easily get the required flow. If you don't you have a problem.
 
That article refers to general recommendations for all experimental aircraft and dosn't properly frame what you may be doing and what most of us do is build, without varying much from the tried and tested, a Vans RV. There are 10,000 flying and the IO-360/390 w/Andair Fuel Pump is in a lot of airplanes.

I'm not saying that level of testing isn't prudent, it's just that, for example, Lycoming already test run the engine before they shipped it to you and you do a fuel flow test as part of your FISDO requirements for sign-off.

It's easy to get the plane to the required attitude for the fuel flow test but not sure I would tie one to a tree and run it up at break-in settings for an hour, seems like a disaster waiting to happen. Maybe in an engine stand, but again, Lycoming did it for you.

Also the running 1 hour on the ground contradicts Lycoming's own break in procedure and a lot of experienced advice out there that says to run it as little as possible until the first flight and then fly it like you stole it:

https://www.lycoming.com/content/hard-facts-about-engine-break

Not giving advice, just framing that article against what you are building. Curious what others have to say.
 
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Work with your DAR. I don't ask anyone to run the engine on the ground for an hour. It should be run once to check for leaks at a low power setting, and then once at full power to check for proper static RPM (both for fixed pitch and for constant speed propellers). Try to keep CHT's below 300 F.

You can check for proper fuel flow without the engine running.

Vic
 
Vic is correct - work with your DAR....but just to clarify, I have never heard anyone who expedite a CONTINUOUS 1 hour run. You can do it in short increments - at the same time you test breaks and steering. Run the engine until you get a little below 300 degrees CHT, then shut down. Cool. Repeat.
 
Sounds good. I remember an EAA article somewhere showing a plane rigged in various positions to check fuel flow; seemed like an experience!
 
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