New rules for experimentals?

Is the old checklist for experimental construction/certification still being used to comply with 51% rule? I know the FAA has taken a new look at the 51% rule recently but haven't heard what changes they have made. I am building a exp cub and don't want to end up with problems. I know several DARs look at this site and hopefully some can offer some advise.

Thanks
Jim Miller

This may not answer your question, but if you are building from a kit that had been previously approved as meeting the 51% (RV-3 through -10, Zodiac XL, Lancair, etc), you should be in good shape. So it will depend on what kit you're using as to whether the current upheaval will affect your build...

From the latest RVator, it sounds like there's a new checklist in "beta", so to speak. But, I honestly don't know what they're using to determine the 51% for the case-by-case analyses in the interim, so I can't help with that part of the question.

"exp Cub" ?

jim miller said:

Is the old checklist for experimental construction/certification still being used to comply with 51% rule? I know the FAA has taken a new look at the 51% rule recently but haven't heard what changes they have made. I am building a exp cub and don't want to end up with problems. I know several DARs look at this site and hopefully some can offer some advise.

Thanks
Jim Miller

Click to expand...

I'm not a DAR but have been involved in aircraft certification and lots of FAA fun. You did not really say much just "exp cub"?

If you're taking a Piper Cub made by Piper aircraft corp, where you are modifying it and calling it experimental, good luck. Not saying it can't be done, just once a certified plane, always a certified plane, short story. If you take parts of a certified plane and put it on an experimental plane, like an RV, like a certified engine and prop, than its NOT a problem, it's experimental.

The best bet is communication with the local FSDO inspector and document the heck out of it with pictures and logs. It does not matter what I say, it matters what the FAA says and the DAR that signs it off. There are kits, plans built and one of a kind customs.


If its a kit than the kit manufacture would have applied for FAA approval of 51% rule. If you try to sell them something that looks just like a Piper Cub (with Cub steel tube fuselage, spar and strut and.....parts) they might say this is a Piper Cub?

Don't be afraid to talk to the FAA. That is what they are there for. If you don't want to talk to your local FSDO call any one of them in any state. It's best to get a larger FSDO that does aircraft cert. Get it straight up and than ask three different FAA'ers to make sure, because believe it or not the FAA is not always consistent.

If an inspector say "NO", it does not mean he's right. If an inspector says SURE, that is no guarantee either. You need the regs behind you. In this matter they are pretty clear.

IF YOU ARE AN EAA MEMEBER, GIVE EAA LEGAL A CALL.

Jim,
At this point, the "old" 8000-38 list is still being used. Are you building a "kit cub"? If so, what kit manufacturer. A few of them are really close to the 51% limit. I've done quite a few. The Texas Sport is the closest one. With the closed cowl, it is 53%. With the open cowl, it is 52%. The Smith Cub and the NorthStar both qualify. If you are building something different, give me a call and we can talk about it. 972-784-7544

Mel
It is a experimental clipped wing cub using a purchased (Spraker) tack welded basic fuselage. I am buying the major fittings (wing and gear attach) and making all minor fittings plus: seats , upper deck with skylight, door, control stick and torque tube, instrument panel, cables, struts, petals, brake system, cowling, firewall, turtle deck, fuel system, vert fin. The uncertain part is I will be using a PA22 tail modified by me to have fixed horz with elevator trim tab. Wings built from damaged PA22 Colt using new Univair ribs and will make new leading edges. I will cover and paint aircraft. I started several month's ago when the old checklist was definitely the only guidelines available and didn't want to discover later than the rules had changed. This project is far more owner built than say a "Turbine Cub Kit" or a breezy which has always used wings and tail components from other certified aircraft.

Thanks
Jim Miller

I have one other question for you DAR's and other knowledgeable builders out there concerning use of certified parts in an experimental. As I can glean from the checklist and from ac27xxx (very little is mentioned on this subject)
there is no difference between say a wing spar or a rib as examples, if they were old piper parts, newly made by univair, or made by van's. The bottom line you can use them but just can't take credit and check the box that you built them. The catch comes when you add up the boxes and fall short of 51% rule. If this is not the case please explain exactly what the difference is between a certified part and un-certified or kit part in the experimental building and certification process and where I can read the exact rule.

Thanks
Jim Miller