Rules? Repowering certified aircraft with experimental engine

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slociviccoupe

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As title states what is rules say taking an older cessna and repowering or powering it with an experimental such as an auto conversion? Does the plane now get registered as experimental? I could care less about it being certified. But buying an older airframe and putting an auto conversion on it seems simpler to me than the years of building.

Plenty of plans and kit built planes id love to have and build. But this option of a pre built airframe, a honda v6 that i know is dead nuts reliable, and a gearbox i can actually be flying and not building for years.

Even with the fabrication and well thought out designing still would probably take a year.

Just seing what the process would be and what i would need while looking for airframes. What paperwork would be needed when buying an sirfrane to actually be able to fky it again.
 

challenger_II

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What are your intentions with the aircraft? What you state is somewhat possible, but there are some serious restrictions on what you can legally do with the aircraft.
 

TFF

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You will have to get a DER to work with and license it as Experimental Exhibition. It will not be experimental Amateur built, so not a homebuilt. The guy with the Chevy V8 in a 172 is the guy to talk too. His I believe is not a US plane but he has done leg work.
 

TFF

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It will be pretty expensive unless you have a DER friend. You literally have to employ this person to run safety calculations and deem it safe. Most EE planes are airshow planes making a buck. That’s how they make things like strapping a jet engine onto a Waco pay off.
 

Hot Wings

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PMD

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the simpler answer is: move to Canada and put it under Owner Maintenance. Problem is: you can't cross back into USA with it unless the US takes a deep breath and looks at the very good stats for safety under OM and lets them in. Better yet: USA could set up OM if EAA/AOPA could get FAA ears to listen. After the Boing-Boing Max debacle, that is not likely to happen.
 

slociviccoupe

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My thoughts were the same to speak to guy with the v8 in the 172. Luckily hes only few hours from me in florida. Long term i want to be able to fly similar to home built experimental. Not limited like exhibition experimental would be. Just read about that.
Prety much like what mike patey has done taking older airframes and doing what he wants and ending up really nice aircrafts. Of course without the bank account or pocket book he has.

I recently had a friend pass from covid and going through his things seing all his unfinished prohects gave me different perspective on life. Not to spend years building a kit plane or built from plans. But to find an airframe and put what i want on it and get in the air.

Not starting debate but im not a fan of aircraft engines. Ive been around plenty of them. And most will say go buy a flying plane. I can agree but not spending that amount of money on a cessna thats ready to fly with an aircraft engine thats due for an overhaul that i cant do myself.
Im not being cheap but also not spending huge amounts.

Only asking these questions because couple airframes complete with wings and tail ive found just with no engine. And relatively cheap.

The same thing appkies as the cessna with the v8. I would be taking a proven airframe and putting on experimental engine. That way im not building a plane and an experimental engine all at the same time. Reduces the amount of variables.
 

TFF

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I think V8 Cessna guy has lots of money in his and I don’t think it was all that cheap in the way you want it to be. It’s cheaper if it breaks or needs an overhaul. First install is not cheaper than an overhauled airplane engine. In the US too many planes are candidates. That is why it will never happen here. Canadian owner maintenance is a factor of small population and vast area. If it had equal population dispersion, no way.
 

rv7charlie

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The restrictions on *operating* an EE are very similar (though not identical) to HBE. As a practical matter, there's effectively no difference. Stay away from densely populated areas, and no carriage of persons or materials for hire.

The maintenance situation is slightly more restrictive. There's no 'repairman's certificate' available, but any A&P can sign off the annual condition inspection (there's no longer a type certificate to comply with, so no IA needed). Any applicable future ADs on an EE derived from a previously type-certificated airframe will likely have to be complied with. After-cert mods can be done by anyone, like a HBE.

Difficulty in moving a plane to EE likely depends on the FSDO. According to my FSDO employee neighbor, there's no DAR involvement required. You need to give the FSDO some legit idea of the proposed alteration that you actually intend to 'exhibit', surrender the original A/W Cert, and they issue an EE cert. IIRC, all the hoops the V8Cessna went through were related to actually certifying the installation (basically an STC process); not to move it to EE.

Charlie
 

sming

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Why not find a flying experimental aircraft needing (or not) an engine and do what you want to do? Is it possible when you're not the original builder?
 

Turd Ferguson

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As title states what is rules say taking an older cessna and repowering or powering it with an experimental such as an auto conversion?

Just seing what the process would be and what i would need while looking for airframes. What paperwork would be needed when buying an sirfrane to actually be able to fky it again.
You should be able to do it without any hired specialty help. There are some other downsides, might want to review those to see if it's worthwhile. Don't be surprised if the FAA discourages you from doing this.

This is a good step-by-step summary of how to do it from a company that supports people doing it:

 

TFF

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There might not be DER/DAR technically required, my FSDO is just going to desk the paperwork and occasionally move it to another desk. What they will tell you is if you want it in a reasonable lifetime, get a DER. It took me 4 years to get a camera mount legalized. They don’t have the depth anymore, like last 20 years, and the engineers in OKC are only a few for the whole country. A re- engine is not some Pitts S2 wanting some experimental propeller that is going to be just bolted on. Doing it through the FAA should be viable, it just isn’t.

I imagine all the cheap airframes you see for sale, we’re bought to steal the engine for a homebuilt or a better version of the airframe. It’s why 0-200s are hard to find and anything that will fit an RV.

172s are airplane school gold. They hold their value too well for the age and would be my last choice to buy. Nothing against them except they hold 30% more value over an equal Cherokee or something else. Unloved 175s seem good except they will have to be re- engined in the next lifetime making them hard keep cheap. Might be what you want to do but if you have to go certified, it’s a chunk. In no form or fashion have I come up with a cheap 4 seat homebuilt that will be cheaper than a cheap certified plane.
 

Mad MAC

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This is a burning money in a drum problem, as in the added value is about the same.

First you have to find a reliable engine conversion all in all these are thin on the ground. Then you need to find a sucker will to do the paper work and hope the FAA accepts it, their time is valuable and expenseand you will still be stuck with exhibt and assocated limits (becuase you know what makes something a lighting conductor, its stucking out which is just what 172 with an automotive engine will do) Then you have to live with the end product which won't be as good as you think, and not cost recoverable.
 

Turd Ferguson

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Exactly what "engineering" has to be done and/or what needs to be FAA approved?

The only paperwork required is changing the type of airworthiness certificate. The owner forfeits a standard airworthiness certificate in exchange for a special airworthiness certificate. The plane no longer has to meet any standard for airworthy. The FAA protects the public with restrictions on how the plane is operated, like a homebuilt. No "for hire" ops, no flying over congested areas, they may limit the number of persons that can be carried, etc.

You end up with a plane that is essentially E/AB but it doesn't meet the major portion rule.
Regardless if it makes economic sense or not I wish more people would push certificated aircraft into E/E.
 

BBerson

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You end up with a plane that is essentially E/AB but it doesn't meet the major portion rule.
Regardless if it makes economic sense or not I wish more people would push certificated aircraft into E/E.
But the application is after the conversion, right?
Who would take that risk of converting without approval first?
 

TFF

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There is a general statement in 21.193 (c) Upon inspection of the aircraft, any pertinent information found necessary by the FAA to safeguard the general public.

You want to use rotten 2x4s and bailing wire or a proper 4130 engine mount. Either way there is nothing to back up why they should let you try if you just say, here it is. DER counts as engineering and peer review in one package. If you do your own engineering, they ship it all to OKC and let the FAA guys do the peer review; at their pace.

There is the program letter that is the reason you want to do it and how you will comply. Places you intend to fly and show it off. Yearly. The FAA does to their credit does let you answer these questions broadly.
 

Map

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Changing a standard airworthiness airplane to experimental exhibition (or other) is essentially a paperwork exercise, no DER (Designated Engineering Representative) involved, just a DAR (Designated Airworthiness Representative). Typically these airworthiness certificates are time limited, anything from a few months to a year. It will take some effort to convince the issuer to get one that is not time limited. Examples where this is easy are imported aircraft from another country that have a standard airworthiness certificate in their country but none in the US. They fit in the experimental exhibition category.

That change in airworthiness certificate should not cost much. Once the airplane is modified, it is stuck with the experimental ticket. It could only be changed back with a major effort, and showing that it again conforms to the standard type design.

For a new engine, you will need engineering support to design the engine installation, if there is no "firewall forward kit" that could be used. Automotive engines are typically heavier than aircraft engines, so the loads are higher, the fuselage structure may need reinforcement, an engine mount needs to be designed, changes to the cg need to be considered. This can make the job end up costing more than just using an overhauled engine that the airframe was designed for. This obviously does not need to be FAA approved, so no DER is needed, but for your own safety an engineer who knows what he is doing should be used.
 

Turd Ferguson

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But the application is after the conversion, right?
Who would take that risk of converting without approval first?
This is what I would do:
First, no conversion. I'm not installing a car engine on a certificated aircraft with the goal of getting FAA approval.
I am using salvaged airplane parts that when assembled look remarkably similar to a 172 (or other spam can) and installing my own non-certificated powerplant. This would be a homebuilt but it doesn't meet the "major portion" rule. Since I can't fly it as a homebuilt, the reason for building it is to exhibit at fly-ins and airshows to educate the public and show the unique characteristics of an auto powered airplane. I'm even planning to race in the airventure cup (or other) race to show the remarkable speed and reliability. 😄

When done and ready to fly, I request an airworthiness certificate (exhibition), send in my program letter to the feds and tell them the aircraft is ready for inspection. The "inspection" will be to ensure compliance with rules for issuing an experimental certificate: e.g., 'experimental' placard installed and visible from cockpit, properly installed registration numbers, passenger warning placard installed if applicable, labels on controls, markings on instruments, etc. They are not going to address or endorse any stress analysis, fatigue failure or other engineering related items. The standard is "safe for flight"
 

BBerson

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This is what I would do:
Would you contact first for permission to remove the data tag? Has anyone done this?

[Obtain written permission from your local FAA Flight Standdards District Office (FSDO) inspector in order to remove the data tag from the salvaged project aircraft. This step represents a great opportunity to develop a positive relationship with the FSDO inspector with whom you'll be working to complete the process. Be straightforward and explain that you require his help in order to certify your project in accordance with 14 CFR § 21.193, under a Special Airworthiness Certificate for the purposes of operating an aircraft in the experimnetal exhibition group 2 - Piston Engine Aircraft category, for the purposes of: ]
 
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