Prop swap

Suppose you decide you want a fixed pitch prop instead of the CS installed. You overhaul or swap out the O-320 to the fixed pitch version, bolt on the prop, evaluate W/B.

Are there any regulatory issues that must be dealt with?

You’ll have to read the Operating Limitations for your aircraft to be sure, but generally a swap between fixed pitch and C/S is considered a change that requires putting the aircraft back into Phase 1 - which usually isn’t a big deal, but requires some time in the test area and some paperwork. Depending on your specific Ops Lims, it might or might not require the involvement of the FSDO.

Does this mean another 25 hours testing?

Chris Scott said:

Does this mean another 25 hours testing?

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Five hours, most likely. That's what the local FSDO wanted when I went to a constant speed prop. Really getting comfortable with the prop and getting a feel for it took at least that long.

Chris Scott said:

You overhaul or swap out the O-320 to the fixed pitch version, bolt on the prop, evaluate W/B.

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I don't think you need to swap out the engine. I took my O-360 from fp to cs, which required removing a plug inside the front of the crankshaft. To reverse this process, you need to install a new plug inside the crank.

https://www.lycoming.com/sites/default/files/Conversion%20from%20Constant%20Speed%20to%20Fixed%20Pitch%20Propeller%20and%20Vice%20Versa.pdf

You would also need to remove the governor & replace with a plate to block that opening.

I'd also suggest evaluating the W/B differences on paper before making the changes. You may find that you need more weight in the front to remain in the CG range.

Chris Scott said:

Are there any regulatory issues that must be dealt with?

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This was quite an ordeal with mine. Getting the initial approval on the 5-hour Phase 1 test flight program was easy, all done over email with the local FSDO. My ops lims required "notifying the aircraft registry branch of the changes" or something similar. Sending an updated paper 8130-6 to OKC as suggested by several knowledgeable people did not work. They returned it to me & said it had to go through the local FSDO. I worked with the FSDO, and they eventually determined that it required an amended 8130-6 to be filed electronically through the new online airworthiness certification system that they are still learning. I ended up with a new airworthiness certificate which is now a single document combined with the (all-new) operating limitations.