Swapping engines as a non-builder owner

[jklPDXPilot]

If I buy a Sonex and decide to swap out for a different engine, what is the process I would have to go through?
I've been looking into the 2nd hand market a bit and have seen some planes that need their engines replaced. If I was to go that route, I may want to go with a different engine.

Changing the engine will change the W&B, so I suspect the original airworthiness approval no longer applies.

These is mostly a hypothetical question because I am still months away from doing anything, but as I'm trying to understand my options.

Thanks,

James

[tps8903]

If I buy a Sonex and decide to swap out for a different engine, what is the process I would have to go through?
I've been looking into the 2nd hand market a bit and have seen some planes that need their engines replaced. If I was to go that route, I may want to go with a different engine.

Changing the engine will change the W&B, so I suspect the original airworthiness approval no longer applies.

These is mostly a hypothetical question because I am still months away from doing anything, but as I'm trying to understand my options.

Thanks,

James

You can do the work as the owner. You'll be required to re-enter phase 1 testing for major changes like an engine. The details are usually in the limitations of the Airworthiness Certificate. It's normally 5 hours of flight testing. Have a look at the limitations of the plane you want to buy as there can be differences.

[Sonerai13]

If I buy a Sonex and decide to swap out for a different engine, what is the process I would have to go through?
I've been looking into the 2nd hand market a bit and have seen some planes that need their engines replaced. If I was to go that route, I may want to go with a different engine.

Changing the engine will change the W&B, so I suspect the original airworthiness approval no longer applies.

These is mostly a hypothetical question because I am still months away from doing anything, but as I'm trying to understand my options.

Anyone can do maintenance, repair, or modification of an amateur-built aircraft. You don't have to be the builder or the owner (or even hold any FAA certificate of any kind) in order to perform these functions. So there's no question you can do the work you suggest.

An engine swap (or even just a swap to a different propeller make/model) is considered a "major change", and there is a process for approving major changes outlined in the operating limitations issued to the aircraft as a part of its airworthiness certificate. The process varies somewhat depending on when the airworthiness certificate was issued, but will always involve placing the aircraft back into a flight test phase (referred to as "phase 1") so the aircraft can be tested for performance, stability and controlability. This test period will be a minimum of 5 hours. Once the aircraft is shown to be controllable throughout all maneuvers to be performed and has no adverse handling characteristics, it can be signed back into normal operations (phase 2).

The first important step is to verify that the aircraft you are thinking about purchasing does indeed have its airworthiness certificate and operating limitations onboard. These documents can be replaced, but if they are missing I would make sure the current owner replaces them before you purchase the aircraft. That way you are getting a legal aircraft when you put your money on the table. The aircraft is not legal to fly without these documents onboard.

[jklPDXPilot]

Thanks.
I'm curious as to the maneuvers that need to be demonstrated.
I'm sure that is documented somewhere along with whole bunch of info I should read.
anyone have a link or document name?



update: googled 'eperimental aircraft phase 1' and found the applicable faa regs,


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