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Thread: Converting Certified Aircraft to Experimental

  1. #11
    Sam Buchanan's Avatar
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    Quote Originally Posted by Skydawg View Post
    ........proficiency flying.......is allowed.......
    Every flight I make is for the purpose of enhancing proficiency.
    Sam Buchanan
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  2. #12
    EAA Staff Joda's Avatar
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    The fly in the ointment here is that the aircraft originally held a standard category certificate. So even if you are successful in converting the aircraft to experimental, all of FAR Part 43 still applies. This means that you still have to have a certificated mechanic do all the work that they would have to perform on the aircraft if it were still standard category, and you will only be able to perform the same "preventive maintenance" procedures that you are allowed under 43 appendix A. You don't gain ANYTHING from the standpoint of maintenance when converting a standard category aircraft to an experimental purpose. You do gain the opportunity to use some non-standard parts, but you give up a lot, not the least of which is the resale value of the aircraft. Also think about insurance. Most insurance underwriters aren't crazy about doing standard category aircraft nowadays (have you seen the rates lately), and they'll be even less interested in covering an experimental version of the same bird.

    Also, an experimental exhibition certificate is not automatic or guaranteed. The FAA is getting pretty picky about what they issue those for. You have to have a valid reason to "exhibit" the aircraft. So before you start down the road of converting an aircraft to experimental, you'd best check with the FAA to see if they'll even play ball with you. I've been down this road with a couple of applicants, and it's not a happy path.
    Cheers!

    Joe

  3. #13
    FlyingRon's Avatar
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    Yes, people miss the second half of 43.1(b)(1)
    Any aircraft for which the FAA has issued an experimental certificate, unless the FAA has previously issued a different kind of airworthiness certificate for that aircraft;

  4. #14

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    You can fly your E-EX airplane pretty much anywhere you want to go within a very large radius, I think that I remember something like 600miles, whenever you want. You create a form letter that you send the FSDO every spring that lists all of the airshows in the country that you might go to and they are happy. Then you go pretty much wherever you want. This required program letter is pretty much a historical relic. List every aviation event in the country in your letter if you want. And don't overthink it.

    The owners of E-EX aircraft that I know are not inconvenienced by it at all.

    That said, you have to do something like put a non-standard engine or propeller on a non-exp airplane in order to get a DAR to move your normal category ship to E-EX. You can't just say you want to do cheaper maintenance.

    Best of luck,

    Wes

  5. #15

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    Exhibition op limits have change considerably over last 10 years. For my C172 there is no geo radius for proficiency or maintenance flights after 40 hr phase 1 sign off. Passengers are allowed, as well as IFR. Again, similar limits to AB. JODA is correct regarding part 43 as it was previously certified airframe, so A&P required. In my case, I have a redundant Delphi EFI system (engine was designed for certification so it has a lot more features than needed for a home built) and other components of my making that no one else can really understand, so I asked for a waiver, technically approval of a maintenance program, allowing me to do engine work and condition inspection. Owner allowed maintenance is mostly required now, such as oil change every 150 hours (50 if I burn lead AVGAS) of Mobil 1 synthetic oil I get at local Walmart.

    The most difficult part of conversion is initial paperwork. You need to demonstrate the modifications you made are safe, unlike a home built. This could require some level of documented analysis, such as a structural analysis by a DER or other qualified entity. Also, you may need to validate any new mods or parts that have or should have a time limited life, such as oil change intervals based on oil lab analysis history, or a component wear limits based on some acceptable means or by your testing using some acceptable basis. In my case, I also needed a pilots operating supplement and specific maintenance manual. The FAA or a DAR will take a good look during aircraft inspection at everything so be prepared for the unexpected as there is a lot of room for discretion on their part. Most of this stuff is out of the skill set of average builder so it can get expensive and likely not worth it for a one off. For me, I had the experience to put this together over time but still had months of back and forth with FSDO and MIDO. I would not recommend it, unless you can find the right MIDO DAR with experience in the EE category, or you buy a complete conversion kit that comes with the required docs.

    again, not a path for most. For me it made sense, i fly the same c172 for about $18/hr that cost me over $60/hr with original O320, has push button start so no more hard starting issues, and it’s easier to fly for my kid without the mixture or carb heat, parts are about 60% cheaper, it’s quieter and more efficient, no lead emissions, and even out performs the newest c172. I just couldn’t rationalize or afford paying the $135/hr rental rate for a beat-up 30 year old 172 anymore.

    FAA policy does allow for non-compensation flight training in EE as well. I’ve been asked to make the same c172 kit for others and put them in a flying club as current c172 rentals cost over $100/hr rental now....this would also be allowed as long as the club was a equity based club wherein members owned part of the plane. This likely wasn’t allowed 8 years ago.

    the GM engine I use is a rated to over 500 HP (the redundant EFI system software restricts to 220 HP which was max certified for the 172), but I am planning on finding a faster experimental airframe to install another engine that I could use a 375 HP limit, which is a good power band for the engine...... A Year of initial engine selection testing I discovered running a V8 consistently more than about 65% it’s rated max considerably decreased reliability and engine life as aircraft and boat engines work exponentially harder than car engines connected to a transmission. If I use an experimental airframe which was never type certified, there would be none of the FAA or part 43 hassles or restrictions.....it would simply be a home built and I could have a repairmans certificate.

    hope this helps update the topic.

  6. #16
    FlyingRon's Avatar
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    Skydawg, yours isn't ExEx is it? It should have been R&D or "show compliance" or later Market Survey.

  7. #17

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    He's not a manufacturer so those categories don't fit.

    As another example of the evolution of FAA policy on Ex-Ex certification, All of the new Extra 330 models are Ex-Ex in the US. Extra has substantiation of the strength of the wing but the FAA wanted them to spend $1 mil to break another wing for the US approval. Extra said no, they would not do that. Their agreement with FAA is to bring in all of the 330's as Ex-Ex.

    I am told that the Small Airplane Directorate is GA friendly and all of this points in that direction.

    Best of luck,

    Wes

  8. #18
    FlyingRon's Avatar
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    I get the Extra thing. But I'm not sure what the issue with Skydawg. Are you saying he's not the one who's trying to get the approval for whatever non-certificated appliance he's got the Ex certificate for?

  9. #19

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    My C172 has a V8 with redundant EFI and other components to meet the FAR 23 standard. It won'r be sold in the US as a certified STC engine package due to liability, so only experimental in US will be offered here other than for POA and restricted categories such as fire patrol ops. The engine is rated up to 375 HP and controlled by software, so its applicable to a wide variety of air frames. The c172's in the US have an EXP-exhibition (EE) airworthiness certificate, the factory demo additionally has crew training, R&D, market survey. There will be an experimental version for AB.

    For the exp-exhibition category (EE), the limitations are about the same as AB. The EE used to have more restrictive op limitations but were revised with a lot of input from EAA about 8-10 years ago.

    Again, I would not recommend someone convert their certified aircraft to experimental, there are plenty of more steps involved compared to AB, and meeting those requirements can get expensive. I'd find a conversion kit like mine that has all the documents needed and step by step process to get the EE AC.

    As mentioned earlier in blog, more and more aircraft are finding their way in to EE category, and it seems to have become the option when other categories don't fit. Many foreign aircraft certified in countries not recognized by the FAA (and/or whose importers don't want to spend the money for FAA certification), as well as military aircraft without a civilian type certificate are in EE. The EE, and all other exp category limitations, now have nationwide standard limitations so there's a lot more standard op limitations depending on complexity of aircraft..... although local FSDO can add as they see fit.

    I think we will be seeing a lot more EE aircraft, especially older aircraft that are just too expensive to keep flying, and who's owners want modern technology at an affordable price and can come up with a good reason to convert to EE. For me, I got an old C172 with a modern FADEC (no carb heat or mixture), cost me about $18/hr (fuel & resv) to fly with current MOGAS prices, it doesn't require an annoying run-up, has a smart engine display that alerts me if something is not right along with a maintenance page that list all system and sensor status- as well as faults with reference to the relevant service manual page (there is even an IPAD app that plugs into the engine computer for more complex analysis and trouble shooting). By far my favorite upgrade is the engine start button for a computerized immediate start regardless of temperatures (I posted a video link below)- I hated trying to hot start the original Lycomings, so this feature is a huge upgrade. My beat up 1969 C172 out performs any new C172 for a fraction of the cost, and would not be possible if certified in the standard category.

    Engine start video:

    https://youtu.be/F7b0iBc5v_4
    Last edited by Skydawg; 06-10-2020 at 08:43 PM.

  10. #20

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    Corsair website has specific info on converting from certified to experimental

    www.corsairpower.com

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