Announcement

**U2fletch** · 2025-05-04T05:19:03

We are doing a BH5 QB and I asked this question of Phil Martineau who built our 2016 Glasair Sportsman in the TWTT program they had. Here is a copy of his response:

"Well, the FAA advisory circular is 20-27G.

Refer to (just as an example) page A8-2.

I'm not the expert, but here's a few comments that gave me some insight:

1. It is a "point/task" based scorecard/evaluation by the FAA. It is not based on cost, time, whatever else you might think.
2. Each task getting points is defined.

3. Original emphasis was (among other things) on education.

4. You do NOT get points for doing something twice. eg if you build a Right wing....you get points.
BUT you do not get ANY points for building the Left wing. You've already learned that task. Simply at it's best, the wings are 1 point, NOT 2 points.

5. Conversely you do not LOSE any points if someone else builds that 2nd wing.

Glasair was brilliant in terms of working the system. They got with the FAA and agreed point-by-point what the scoring tasks would be.
And this let them craft the work for TWTT that maxed (well, got to precisely 51%) the "owner built score" while minimizing the time/effort for the owner involved.

However, MOSAIC is coming, expected by the mid to late summer, and will change a lot of this. The "aha" for the FAA was realizing that owner-built airplanes ASSISTED by professional build
resources/firms were safer statistically. ie Rather than fighting against the build firms, safety was improved/enhanced by supporting them!

Just one pilot's perspective. But I've been involved over the last 20 years in this dialogue!

Best
Phil"

And from my research there are a few items that are not included in the numbers such as avionics, wiring, upholstery, paint. It's kind of expected that you would outsource these items.

**TedGarcia** · 2025-05-04T09:35:28

Yes, I have been watching MOSAIC and it seems likely the BH4 could be classified as LSA under the clean stall of 54 knots. Not sure what that gains me personally - but certainly opens the range. It will be interesting to see how MOSAIC impacts the experimental inspection process. And given that I will not be complete until 2026 that will be my path.

Appreciate the reply - so I wasn't missing anything, it is a point system based purely on tasks. You are correct that the AC specifically calls out paint, upholstery, avionics, engine building, prop building, wheels and brakes as something the builder can outsource.

I decided to go the BH4 route since it fit my mission in terms of size, performance envelope and cost - though I am wondering about that as I have had a dozen people as why I didn't go with the "newer, bigger, faster BH5"...there is no one plane for all missions

The BH4 QB (Bearhawk Quick-build Kit, Bear Tracks Assembly Manual, dated June 2002) seems to be on the FAA list been evaluated and found eligible in meeting the “major portion” requirement of Title 14, Code of Federal Regulations (14 CFR) Part 21, Certification Procedures for Products and Parts, specifically, § 21.191(g) for build manuals dated back in 2002. I will do some digging and see if that ties to an AC 20-27 list somewhere.

I figured it is better to be ahead of the documentation process, chat with the FSDO and EAA along the way, and avoid surprises when ready to fly!

Best
-ccc

**jaredyates** · 2025-05-04T09:39:03

This is the 2002 task list. A lot has changed about the policy since then.
FAA-51percent_tasklist.pdf

**Bcone1381** · 2025-05-04T17:28:25

Originally posted by TedGarcia View Post

Making progress on my BH4 Quickbuild and preparing FAA paperwork along the way. Has anyone completed Appendix 8 of AC 20-27G for a kit? I assume each task is a point, add the points, divide by the columns and the builder gets to 51% or does not. It is interesting that "Assemble Avionics to Instrument Panel" is one task - so if that is sourced to commercial assistance it is a minor impact to the percentages.

There are a couple of head scratchers on the list. Fabricate Engine Compartment Overheat/Fire Detection System is one. Is this as simple as CHT and EGT sensors wired back to the Engine Monitor?

Curious how others have approached this. Going to chat with EAA as well.

I completed the task list. I think "Assemble Avionics to Instrument Panel" means you took a few hours to mount the instruments in the panel using hardware and tools No Wiring, No pitot static, no harness, no switches, no lights, no control cables. Just instruments mounted on the panel. I never flew a piston aircraft with an Engine Overheat System. The Engine Overheat task is probably not installed, and I would put NA. I see that as a heat sensor that ring a bell when it senses and overheat situation.

You can see that this checklist is subject to how one views each task. If you want to view the CHT and EGT that way, go for it and be able to back up your checkmark. I just did not think like that. Nothing wrong with calling it a warning system. I can see that now. Just make the call what you think it means and move on.

I approached it this way. If a task was completed using amateur builders then the point was assigned that catagory. I gave partial credit in a few areas. I think each task is worth a point. So if the Kit Manufacturer fabricated something, but I threw a 1/2 the parts out and made my own, or modified the part, then I took part of the credit. If I build one wing but not the other I'd have given myself partial credit. I'm not saying that to start a dramatic discussion about intent of how we count points. It just how I approached it.

I had a friend look it over and he came up with his score. We compared and I could see how he thought. Thats cool man! I changed a few things.

My advice is to I fill it out as a study now as you think you will build it to see where you are. If your short, then call Virgil. He knows best I think. Consider yourself having a short time to convince the FAA that your craft meets the 51% rule. Using the worksheet is one way they can determine that. I had mine ready for the FAA when they did my inspection and I dont recall them asking or looking at it. But I was ready.

Its kind of strange that we spend all our time and all the money to build but then feel like I have to prove to the FAA that its really in compliance. I felt like they could say "I dont think so." then I'm left with an assemble of parts. This check list gave me peace that I was entitled to the AWC Entitlement is a word I rarley use. But if we do the build right then we are entitled to an AWC.
Screenshot 2025-05-04 at 8.16.30 PM.png

**gregc** · 2025-05-04T19:50:13

If you like reviewing and interpreting FAA regs and guidance, more power to you. If not, consider hiring a DAR for the inspection instead of the using the FAA. In my region the FAA no longer does EAB inspections (you have to use a DAR) and given the level of staffing cuts at DOT I doubt the FAA will be doing it anywhere in the future. Talk with DARs near you to find one that shares your priorities. In my case I said that while I understood that I needed to have the paperwork completed correctly, safety was my primary goal. A good DAR will tell you what paperwork they want to see and will likely review it with you before entering it into the FAA system. Regarding the 51% rule, the 4 place is on the approved kit list already. I don't know about the other models but the great majority of DARs won't know or care about the differences between model 4 and 5. Unless you plan on getting a lot of commercial support to build your plane, I don't think the 51% rule is an issue.

**flyboy** · 2025-05-05T08:20:14

We used a DAR in Oregon. Let me know if you need a name.

Announcement

20-27G FAA Checklist Points - the 51% Rule

20-27G FAA Checklist Points - the 51% Rule

Comment

Comment

Comment

Comment

Comment

Comment