Sonex-A purchase - What to look for

[Hambone]

Long-time lurker here, first post!

I'm heading out to look at a used Sonex A-model/Aerovee in Pennsylvania. It looks like an amazing build, only 60 hours flying time, and the current (2nd) owner is very knowledgeable, experienced, and helpful, and has a genuine reason for sale.

https://www.barnstormers.com/classified ... -2017.html

I'll fly with the owner for a few days, and if I decide to buy, undertake the long cross-country home to California (avoiding the Rockies!)

I'm trying to gather as much information as I can. What specifically should I be looking for on inspection? What should I test in the air? I have 3,000+ hours, so I'm not worried about the flying aspect. What concerns me most is the reliability of the Aerovee. There seems to be a mixed bag regarding engine safety, but there are an awful lot of Aerovees and Aerovee Turbos out there, so they can't be THAT bad!

Thanks to all in anticipation!

Mods: If there is a better category to put this in, please move it. Thank you.

[daleandee]

What concerns me most is the reliability of the Aerovee. There seems to be a mixed bag regarding engine safety, but there are an awful lot of Aerovees and Aerovee Turbos out there, so they can't be THAT bad!

My Aerovee Sonex took me from Carolina to Tennesse a couple of times for the American Sonex Association Gatherings (thank you John Davis). Lots of Aerovee powered Sonex aircraft would attend and some came from far distances (Charlie Radford & Bob Mika come to mind). During flights in my Aerovee nose roller I had to watch the oil level and top it off at fuel stops but otherwise it was fine. Climb rate in a fully loaded plane at higher altiutudes with the Aerovee isn't spectacular and engine temps can be a concern.

I met Phil Simon at the American Sonex Association fly-in. Here's a good article he wrote about all the flying & the many hours he put on his Aerovee Sonex:

https://www.sonexaircraft.com/phil-simon-1007/

I'm a Corvair zealot these days but the little VW worked well enough to make me fall in love with the airplane.

Dunno if this helps ...

Dale
3.0 Corvair/Tailwheel

PS: That's a great looking plane BTW.

[Hambone]

Thanks, Dale! That’s great to know. It certainly helps to inspire confidence in the AeroVee.

Phil’s diary is a great read, and full of useful information. It’s always good to be prepared, and reading about the trials and tribulations of others is a good way to help avoid making the same mistakes!

[MichaelFarley56]

I agree with Dale...that is a beautiful looking Sonex and I hope it's exactly what you are hoping it will be!

There is a lot to consider when purchasing a Sonex and I know it's easy to focus on the engine, which I will certainly discuss, but as for the airframe itself, a few things to consider:
- Look at rivets: the rivets should be in the middle of any flange area on ribs, gussets, etc. The pictures make this airplane look really nice and I'm sure it is, but I'd try to grab a flashlight and inspect as many areas as possible to make sure all of the parts are riveted and/or bolted together correctly and are secure by making sure the aluminum tabs and parts are to secure, and rivets and bolts look correct.
- Check any black pushrods for flight controls especially at the ends of those pushrods to make sure everything is tight and secure.
- Check the landing gear and wheels as much as possible to make sure everything is secure, there is no play in the wheels or axles, and nothing is leaking. Check tires for proper inflation and no flat spots.
- Make sure there are no cracks in the canopy or windshield
- Make sure the fiberglass parts don't have any cracks or fitting issues.
- Make sure all of the lights and/or avionics work properly and the wiring looks uniform

As for the AeroVee, the core of the engine is solid so the main thing to check is compression of each cylinder if at all possible. A good check of the crank and camshaft bearings is the oil pressure: it should be at least 10 psi per 1000 rpm (for example, 30 psi at 3000 rpm cruise). If it meets or exceeds that, that's a good sign!
The valves are the main "weakness" of the AeroVee so perform a compression check if at all possible. If you can't, insist on an oil change and head torque check prior to leaving to make sure the head bolt torque values are in order. Othewise, make sure the engine is producing proper power (3000 RPM on takeoff is preferred) and there are no excessive oil leaks. You can normally tell a healthy engine by cool CHT temps (well below 400 CHT is preferred), good oil pressure as previously noted, and normal oil temps (below 210 degrees). Finally, check the prop bolts to make sure they are torqued properly.

Let us know how it goes and what you see as you look the Sonex over!

[Bryan Cotton]

We are coming up on 240 hours on our AeroVee. Biggest issue is oil leaks. More of a mess and nusiance than a safety hazard. Biggest single XC was a bit over 460 miles. I want to fly to Sun-n-Fun some year. My biggest worry is spousal, not engine. My engine was built by my then 15 year old.

Weight is critical. Ours is a little over 670 lbs. Performance at that weight is decent solo, and low with two people. I'm jealous of the people with 650 lb airplanes. I know there are some over 700 and that would make it a single place with low performance.

Mixture setup is critical. You should be able to lean for peak RPM and get the EGTs high but under redline. My AeroVee does not run well rich. Too lean is bad too. When set up properly it is easy to manage. Don't expect all cylinders to match EGTs without applying weird science. I'm working on that.

Jack up the airplane and check how solid the main gear is. Same with the tail gear.

Search for Waiex 191 on YouTube and you will find two channels, mine and my son's. Lots of AeroVee powered informal instruction, cross country, and aerobatics.

Everything will need safety wire eventually. Oil pressure sender, valve covers, oil sump, air filter, wheel pant axle bolt, and so on. Those are the things I can think of offhand. For sure the AeroInjector should be safetied as per the manual.

[Hambone]

Mike & Bryan - thanks for the most welcome and useful information! I'm creating what I hope is a comprehensive and effective pre-buy checklist.

[Bryan Cotton]

Oh yeah - electrical load. You only have 20A to work with. Some of that is for recharging the battery after start. Some of that is to run the secondary ignition for takeoff, landing, or a failure of the primary ignition. How much is left over? Beware overdone Sonex electrical systems.

Also see this for when you get home:
viewtopic.php?f=6&t=7412

John Deere for the win. Believe me!

[Hambone]

More photos, kindly supplied by the owner:

[Barry63]

Guys, if I'm not mistaken, this sure looks like Darrick Gundys Sonex, #1646 from a few years back. The paint scheme and that is in PA, only about an hour and a half east of me, is what made me think it was his. If I remember correctly, he sold it to someone from his home field.

Hambone, go into the Photo Album and look down the list for Darricks 1646. It's not very far down the list on the first page. He has a TON of build pics on there.

I would have bought it when he initially put it up for sale but couldn't afford it as I already own a 172. Hope this helps you out.

[Hambone]

Thanks for that, Barry. It is indeed Darick's build.

I'll definitely go through the photos!

Edit: I can't seem to see many of the photos, only the word 'image' where I would expect to see a photo.