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Major and Minor Mods to Experimental

Jim Miller

Registered User
Normandy TN
What is required paper-work wise for a builder with repairman certificate
to modify his homebuilt in a minor or major way? How and who determines what is major?

Thanks
Jim Miller
 
I've done this a couple times and should have done it a couple more and didn't. It's been a few years though. First, reread your operating limitations. It should tell you what to do. All I did was concact the FSDO and they came out, looked at the airplane and put me back in Phase One testing for five hours.
 
PAPER WORK

I PRETTY SURE THAT IF MODS ARE MADE THAT WILL CHANGE THE WAY YOU FLY THE A/C (FLIGHT CHARACTERISTICS) THAT YOU WILL HAVE TO GO BACK INTO PHASE 1 FLIGHT TESTING AGAIN.......YOU KNOW, CAN'T FLY FUTHER THAN 25 MILES FROM HOME BASE AND CAN'T HAUL ANYONE ELSE FOR A PERIOD OF 25hrs OR 40hrs DEPENDING ON IF EITHER ENGINE OR PROP ARE EXPERIMENTAL.......AND I BELIEVE YOU HAVE TO NOTIFY THE PERSON THAT ORIGINALLY INSPECTED THE A/C AS WELL AND POSSIBLY HAVE TO HAVE ANOTHER INSPECTION .......AT LEAST THATS WHAT MY DAR TOLD ME.........SUCKS DON'T IT :crazyeyes:
 
Jim Miller said:
What is required paper-work wise for a builder with repairman certificate to modify his homebuilt in a minor or major way? How and who determines what is major?

Jim,

First of all, the "repairman certificate" actually has nothing to do with repairing (or modifying) the aircraft. There is no requirement for any FAA certificate when performing maintenance, repair or modification on an experimental aircraft. The "repairman certificate" is only required when performing the annual condition inspection. The name of the certificate is misleading in this case.

Also, there is no such thing as a "minor" modification on an experimental aircraft. The only thing that would require action by the owner/operator is a "major change" as described by 14 CFR 21.93. And in perfect FAA fashion, 21.93 doesn't actually describe a "major change"! It describes a "minor change" and then goes on to state that anything that doesn't fit the definition of a minor change is a major change. (Still following??? :) )

Ok, here's what 21.93 says...

A “minor change” is one that has no appreciable effect on the weight, balance, structural strength, reliability, operational characteristics, or other characteristics affecting the airworthiness of the product. All other changes are “major changes”

The operating limitations issued to the aircraft as a part of its airworthiness certificate will include language that outlines the procedure for approval of a major change. The owner/operator needs to follow the procedure as outlined in the operating limitations if they want to incorporate a major change to the aircraft.
 
Joe
Thanks for the reply. I am getting way ahead of myself here, as the project is about 18 months away from flying. This question came up locally and everyone seemed to have a different opinion.

JM
 
Jim Miller said:
This question came up locally and everyone seemed to have a different opinion.

That's not surprising. There are many within FAA who don't understand this stuff!! I spend a fair amount of my time educating the FAA on their own rules and policy. It's no wonder there's confusion in the field!
 
Hi Joe
How about regulations for certified engines in an experimental aircraft. Are they still subject to AD's. Can an owner, but not the builder do major engine repairs? Or are the engines considered experimental once installed in an experimental aircraft? Part 43.1(b) implies experimental's are not subject to the regulations for maintence, unless they where previously registered in a different category. Would this also then apply to engines?
Keith from HXF with the clipped taylorcraft wants to know!
Thanks
Dan
 
planenut said:
How about regulations for certified engines in an experimental aircraft.

Dan (and Keith),

The experimental airworthiness certificate applies to the entire aircraft, including all installed components and accessories. This being the case, the exemption called out in 14 CFR 43.1(b) applies to the entire aircraft including all installed components and accessories. What this means is, ANYONE can perform maintenance, repair and/or modification to the entire aircraft. "Anyone" truly means anyone. You don't have to be the builder, you don't have to be the owner, and you don't have to hold any FAA certificate of any kind in order to perform maintenance, repair or modification on any part of the aircraft (including the engine).

With all of this as background it's pretty easy to see that the engine cannot be considered to be "certified" or "certificated" when non-certificated individuals are allowed to perform maintenance and repair. In short, an engine installed on an experimental aircraft is itself "experimental".

Now, as for ADs, the official word from FAA legal at the headquarters level is that ADs do not directly apply to formerly type-certificated components installed in experimental aircraft. however, this does NOT mean that you can simply ignore an AD that may apply to a component of the aircraft. The reason I highlighted directly is because there is an overlying requirement that the aircraft be maintained and operated in a condition for safe operation. So, since an AD points out an unsafe condition it would be difficult for the owner/operator of an experimental aircraft to completely ignore an AD and still claim that the aircraft is in a condition for safe operation. To be completely legal the owner/operator must address the safety concern pointed out by the AD. But you would not be required to comply with the letter of the AD. You are free to respond to the safety issue in any way you see fit, so long as you somehow address the safety concern pointed out by the AD. Many times the easiest way to do this is to simply comply with the AD, but the owner/operator of an experimental aircraft has the option of coming up with an alternate response to the safety issue pointed out by the AD.

Clear as mud, huh!! :)
 
Joe
Is it possible to keep your certified engine certified if you allow and document that only certified personnel maintains it. Get yearly engine annuals by A&P and do everything relating to the engine as you would if in a certified airplane.

Thanks
Jim Miller
 
Jim Miller said:
Is it possible to keep your certified engine certified if you allow and document that only certified personnel maintains it. Get yearly engine annuals by A&P and do everything relating to the engine as you would if in a certified airplane.

Jim, Matt is correct. Once the engine is installed on an experimental airframe and operated under an experimental airworthiness certificate it is an experimental engine. No way to avoid it. This is due to the fact that Part 43 does not apply to the aircraft, so there is the possibility of non-certificated individuals doing maintenance, repair or modification to the engine and there is no legal requirement to document such work. Also, the engine cannot be operated in compliance with a type certificate when it's installed in an non-TCed airframe. Thus the engine is experimental no matter what.
 
Okay Joe, don't mean to get this topic off the original subject but if I were to buy an experimental flying or damaged.....and proceeded to fix and problems (repair the damaged plane) I can legally do all this? Of course I would need to get the Condition Inspection done by an A&P.

The reason I am asking is I am trying to get my brother into flying and he has been looking at several Kitfoxes that are either damaged or in need of finishing. He wants to do the work himself and then get it inspected later.
Thanks,
WW
 
WWhunter said:
Okay Joe, don't mean to get this topic off the original subject but if I were to buy an experimental flying or damaged.....and proceeded to fix and problems (repair the damaged plane) I can legally do all this? Of course I would need to get the Condition Inspection done by an A&P.

Yes you can. Remember in my earlier post I mentioned that ANYONE can perform maintenance, repair or modification on the aircraft. This means anyone!! You don't have to be the owner. You don't have to be the builder. You don't have to hold any FAA certificate of any kind. The only time a certificate is required is when performing the condition inspection. The person who holds the amateur-built or LSA repairman certificate for that particular aircraft, or any A&P mechanic (IA not required) can perform the condition inspection.
 
I have recent experience in this. I put a new engine/fwf of different type in a exp that I purchased. I went down the road of getting an A&P to inspect and sign off. He and I learned that you can't do that, even though this had been done by A&P log book entry in the past for this very same aircraft. I hired a contract DAR and received a new airworthiness certificate and operating limitations. All it takes is money.
 
Joe (Norris)
How would it work in this case: I build my exp clipped wing supercub with a tailwheel and later decide to temporarily convert to a testerman nose gear, install and do the necessary weight and balance. Now if this was a certified cub I could have any A&P do this with a simple logbook entry as it appears on the type certificate. Could I do the same thing holding a repairman's certificate for my exp? Would it be advisable to get mention of this possibility in the original airworthiness cert?

Thanks
Jim Miller
 
Major Mod to Experimental

The work you describe is a major mod. Check your operating limitations for exactly what you are supposed to do, but most likely you should contact your local FSDO and inform them of what you have done. They will assign you a test area and specify a flight test period (probably 5 hours). Go fly the test hours off, make the appropriate logbook entry yourself, and go have fun. No A&P is required anywhere in this process.

If you do not hold a repairman certificate for this airplane you will need an A&P for the annual. That's it.
 
Dave
Would it be possible at the time of initial certification to have two separate
weight and balances, one for nosegear and one for tailwheel. Certify as a convertible aircraft and do two periods of flight testing, one for each configuration. Then be free to convert back and forth between nose/tailwheel as desired using the approriate weight and balance?
As I recall in the past there have been exp/kitplanes with this capability.
A piper J-3 or Pa-11 has this capability per the type certificate with the testerman gear. There should be some method to achieve the same result under more lax experimental rules.

Thanks
Jim Miller
 
Major Mod

I don't know if you could get a signoff from the DAR for both configurations at the time of initial airworthiness certification. My guess is No, because you must fly test hours for both configurations to verify flight characteristics, but it wouldn't hurt to ask.

I had a GlaStar that could have either trike or conventional gear. I started out with a trike and then switched it to TD later. I flew the 5 hours off after the TD changeover and had a new weight and balance for that configuration. I also kept the old gear and W&B.

At a later date I switched back to the trike gear (after a minor mishap in the TD configuration). I simply made a logbook entry and dug out my old W&B when I switched back. Because I had flown off test hours for both configurations I assumed, hopefully correctly, that I did not have to go through the major mod process again.

I would suggest that you fly off your initial phase I test hours in one configuration, and then go through the major mod process for the other configuration. You should probably ask your DAR about the legalities of going back and forth with your gear just to be sure.
 
Jim Miller said:
Would it be possible at the time of initial certification to have two separate weight and balances, one for nosegear and one for tailwheel. Certify as a convertible aircraft and do two periods of flight testing, one for each configuration. Then be free to convert back and forth between nose/tailwheel as desired using the appropriate weight and balance?

Jim,

Yes, this is possible. It happens with Glastars with floats and wheels all the time. The basic premise is, you can't do anything during normal operations that has not been tested during a flight-test phase. So, if you want to approve two different landing gear configurations, or 5 different props, or two different canopies on a powered parachute, or whatever, you can figure into your flight test plan to test all configurations before completing the flight test. Once each configuration is tested you are free to switch back and forth as much as you like just by making a logbook entry.

No repairman certificate is required for this type of change. You do not have to be the builder, or the owner. Anyone is allowed to make major changes at any time. But each change must be tested in a restricted area under "phase one" conditions before you are allowed to operate the aircraft in the new configuration during "normal operations".

Remember that the initial flight test phase (aka "phase one") is for a prescribed minimum number of flight hours. There is no maximum. You are welcome to test for as long as you like, and you can test as many configurations as you like. Air racers do this all the time with propellers. All that's required is that you do a separate entry in the aircraft records for each configuration, as specified in your operating limitations.

Hope this helps!
 
Dave, Joe
Thanks for the info. Being able to convert back and forth is good insurance for a person with zero tailwheel time. After I get my Tail wheel endorsement and some experience maybe it won't be as big of an issue. In any case I am glad that it won't be that hard to do regarding the certification for both configurations.

Thanks
Jim Miller
 
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