I came a across this ad on barnstormers for an almost complete fuselage and tail subkits for a sonex-B. The owner sent me some pictures.
Here’s where I’m at, I regularly fly a turbo saratoga, so I’m not in a hurry to get a plane. For me I understand that the Sonex is a long term project that will probably take years to complete properly. I’m in it for the learning journey and of course the fun at the end.
so my questions
what should I look for in a partially completed subkit like this?
how can such a deal be fairly priced, I understand that life gets in the way and I hate low balling people, but I heard from several builders that partial kits are typically priced lower due to the amount of effort needed to validate it was put together or other considerations, these were RV builders though, so maybe sonex plans are simpler?
If you have an opportunity to, ask to see the build logs for what the previous builder has done. My opinion is that you can (somewhat) judge workmanship on how detailed the build logs are (plus, you can ensure documentation exists to prove it was truly amateur built). As far as overall condition, nothing stands out in the pictures you posted to make me question build quality. In general, I would be checking that rivets aren’t missing in holes (the plans can help you determine which ones shouldn’t be installed yet; look for one rivet missing when it’s neighbors are installed), places where it looks like an assembly is forced (wrinkles in skin or odd-shaped overlaps, and edge distances (holes too close to the edge of parts).
Regarding pricing for something like this, I tend to discount whatever labor the previous builder put into a project (but that’s just me). When I purchased my second-hand tail kit, I had about 30 hours into inspection and re-work so I didn’t save as much time. Assuming that what you’ll be purchasing is a complete fuselage and tail kit, it looks to be about a 50% savings which I would think is fair.
If you do go down the used kit route, make sure to register the sale with Sonex via a ownership transfer form so you are able to purchase parts going forward. Then ask them for the original packing list (if the seller doesn’t provide it) to make sure you aren’t missing anything. Then go through the plans page by page and validate what has been built so far. That way, you’ll have a full understanding of what’s been done and how the components interact with each other.
Here are some thoughts, which may not compose the answer you seek, but will help you get there.
The modern Sonex kits are really easy to build. Prelocated holes and pop rivets. 90% of the build being good is:
Updrilling and deburring holes - standard aircraft practice.
Building on a flat surface to make everything true.
Following the instructions.
So in the pics those parts have a pretty good probability of being good. The fact that it is in a hangar says that hopefully the person who built it is an aviation person and maybe aware of the points above. If it was built by a first-timer with no aviation experience, that’s not a bad thing as long as they followed those 3 things above.
Probably the two most important things are the wing rigging and tail attachment to the fuselage. They are critical - wings or tail falling off is bad. The wings haven’t been done yet, and not sure if the tails have been drilled in or not. Even if that is screwed up, you can replace parts and do it over, but it takes a lot of time and some money. So that is the gamble. I know of at least 2 A model aircraft where the wing attachment was buggered up. One by the guy who was doing the project, one by a guy local to me who bought a flying project with some issues including snowman holes in the wing attach. So that is the gamble. On this project only the tail looks mounted and I think that task is easier than the wings. Also, if I understand correctly, the B models went to the wing rigging procedure that some of us used in the A models - drill the spars to size, then use a bushing to transfer holes to the fuselage. Originally the Sonex procedure was a piloted drill bit and that went poorly for a lot of people.
If that kit has been built well, it will save you between 1-5 years assuming you are a normal person. It’s like getting part of a quickbuild kit.
So, it’s a slight gamble. It will likely save you a bunch of time and some money. But if anything is not right then you need to spend whatever time and money you need to make it right. That’s really true if you are the original builder who finishes a kit too.
The one downside for me is that the fuselage isn’t polished. If you are into the polishing thing it’s really better to polish the parts on a table before riveting. Saves 15-40 lbs of weight depending upon the paint job.
If you purchase it, make sure you have them create an FAA aircraft bill of sale with the word aircraft crossed out and replaced with kit. You’ll need this for registration.
Other things to consider besides the above is to consider additional cost for missing parts or if you want to change the configuration to how the kit was spec’d. For me this added a good amount of cost but I still came our far ahead of a new kit.
