51% rule

[dgapilot]

In the stretched pacer thread comments were made about 51% rule. The OP asked to move that to a different thread. So here is my take

All DARs are given guidance that they are to use the current version of Order 8130.2. For Experimental Amateur Built Aircraft, that Order drives us to the “fabrication and assembly checklist” found here
https://www.faa.gov/aircraft/gen_av/...syCklistFW.pdf
If you are building an aircraft that you plan on trying to go EAB, use the checklist to determine if you will meet the requirement.

I’ve had two aircraft so far that I could not issue an Experimental Amateur Built Certificate because they couldn’t meet the 51%. I was able to issue an Experimental Exhibition, so at least they can fly.

In short, do your homework ahead of time so you aren’t hit with a surprise at the end of a multi year build.


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[Jim Hann]

Question from one side of this topic. I'm hacking away at a Fly Baby project that was started in the 1970s, I don't have much of a build log for it besides a couple of tech counselor visits, no airframe log either (it was started back in the days of pre-cover inspections). Since it is a plans built AND I have evidence of it being started under the previous "definitions" where do you think I'll stand?

IMG_6594.jpg

[dgapilot]

Question from one side of this topic. I'm hacking away at a Fly Baby project that was started in the 1970s, I don't have much of a build log for it besides a couple of tech counselor visits, no airframe log either (it was started back in the days of pre-cover inspections). Since it is a plans built AND I have evidence of it being started under the previous "definitions" where do you think I'll stand?

IMG_6594.jpg

Plans Built should be no problem as long as you didn’t use “commercial assistance”. The previous builders tasks still count towards the major portion. Doesn’t matter who was working on it so long as it was for recreation or education.

The problem people run into is using major assemblies from previously certified aircraft. In that case, any work on those assemblies doesn’t count as part of the building process, that is considered maintenance under part 43.


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[Stephen]

In the stretched pacer thread comments were made about 51% rule. The OP asked to move that to a different thread. So here is my take

All DARs are given guidance that they are to use the current version of Order 8130.2. For Experimental Amateur Built Aircraft, that Order drives us to the “fabrication and assembly checklist” found here
https://www.faa.gov/aircraft/gen_av/...syCklistFW.pdf
If you are building an aircraft that you plan on trying to go EAB, use the checklist to determine if you will meet the requirement.

I’ve had two aircraft so far that I could not issue an Experimental Amateur Built Certificate because they couldn’t meet the 51%. I was able to issue an Experimental Exhibition, so at least they can fly.

In short, do your homework ahead of time so you aren’t hit with a surprise at the end of a multi year build.


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This is an important question as I talked with a number of people who want to build an experimental Bushmaster. I question if just lengthening the fuselage and wings meet this requirement. Especially, if you are using manufactured parts. I agree that they contact theIr DAR first.

[Bob.shea]

Jim contact your local DAR My first project was like your and he was a great help to me and made life a lot easier

[Steve Pierce]

dgapilot, Why couldn't you approve the two?

Interesting how you can spend 40 hours at Cub Crafters and and walk away with an experimental homebuilt. Always a loophole.

[dgapilot]

dgapilot, Why couldn't you approve the two?

Interesting how you can spend 40 hours at Cub Crafters and and walk away with an experimental homebuilt. Always a loophole.

Steve, one was a kit built airplane that had been issued an Airworthiness certificate (E-AB). The owner was concerned about liability and turned in the registration as destroyed, and surrendered the Airworthiness certificate, and drilled off the data plate, then sold the airplane as parts. The new owner tried to register it with him as the builder, but same serial and model. Red flags at the FAA! If he had registered it with the original builder, I might have been able to issue a “replacement” certificate, but once the FAA got involved my advisors told me not to issue an E-AB.

I don’t really remember the circumstances with the second one, it was many years ago.

Long story short, use the checklist before you start the project. It doesn’t prevent the use of major components, you just can’t claim credit.

Bye the way, it has nothing to do with hours. The checklist identifies “tasks”. You need to complete 51% of the tasks. FAA even has a publication on how to fill out the checklist.


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[Jeff J]

Just reading through the checklist linked above and what the EAA has on the website, the 51% rule seems pretty cut and dry to me. In short, if you didn’t fabricate and/or assemble it, it don’t count. I can see where someone may think if they cut up a fuselage to modify it they may think they built something BUT it is actually a major alteration and should be treated as such.

Now, for my silly questions... wouldn’t it be better to just build a new fuselage? It seems like there are a lot modifications that have to be done beyond cutting and extending a few tubes. What about buying a Wag project to work with instead of cutting up a good (or repairable) certified airplane? Either way also ends the 51% concern for the fuselage if trying to go experimental.

[dgapilot]

And I know of one airplane that was issued an E-AB certificate, and a year or two later, FAA took it away. Then issued an Experimental Exhibition to that Aircraft. It also involved switching data plates. It started life as a Monocoupe 90A, and ended up as a Monocoupe 110 Special. Unfortunatly the owner and a good friend was killed in it several years ago.


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[Stephen]

Just reading through the checklist linked above and what the EAA has on the website, the 51% rule seems pretty cut and dry to me. In short, if you didn’t fabricate and/or assemble it, it don’t count. I can see where someone may think if they cut up a fuselage to modify it they may think they built something BUT it is actually a major alteration and should be treated as such.

Now, for my silly questions... wouldn’t it be better to just build a new fuselage? It seems like there are a lot modifications that have to be done beyond cutting and extending a few tubes. What about buying a Wag project to work with instead of cutting up a good (or repairable) certified airplane? Either way also ends the 51% concern for the fuselage if trying to go experimental.

Good ideas....But,

Building a new fuselage is a huge project. Much much bigger than doing a fuselage extension and a Wag is not very similar to a late model PA 22. The builder might get credit for replacing everything in the fuselage aft of the baggage area. Plus you would get a much straighter looking fuselage. You might also get credit if you build your wings from blank spar material. Maybe you would get credit from building new control surfaces.