Prop Strike Damage Assessment

[Twosblind]

Hello,

I am considering buying a used Legacy Sonex that was involved in a prop strike incident after a botched landing and was looking for opinions on the extent of damage to the airframe. I fully realize this is impossible to truly assess via the internet but any guidance would be greatly appreciated.

The aircraft has an aerovee engine that is probably a total loss (I plan to convert to a Jabiru anyway) and the engine mount appears to have suffered a slight tweak which doesn't concern me since I will be getting a new one anyway. What does concern me is where the engine mount attaches to the airframe. The top two aluminum angle iron supports appear to be bent. The bend does not appear to be serious but still concerning. Pictures of this are attached. Worst case scenario, are these easy to replace?

Secondarily, one gear collapsed during the landing enough to strike the left wing of the aircraft. There is very light damage to the sheet metal on the wing and one rib has a slight crease from the hit (pictures attached). This is something that doesn't concern me much but I wanted to get opinions on whether a rib replacement is warranted.

Overall, the aircraft appears to have excellent build quality and the seller is very upfront about the issues that need addressing. An airworthiness certificate was issued in 2010 and the aircraft flew from then up until the accident in late 2021. Thank you in advance for your help!

[lgsievila]

Hard to really tell from the pics but what I see would cause me to pass on this airframe. While I built a Onex, not a Sonex, I believe you might be able to save the wings but you probably would have to rebuild the entire front half of the fuselage. Think you would be better off trying to find an unfinished partially built kit IMHO

[Bryan Cotton]

My assessment is different from Loren's. I don't have my plans in front of me but I believe those angles are held in by the phillips head #10 screws on the corners. If you were replacing the motor mount anyway then it would be good to change those parts, because you could match drill them starting with a #40 bit and working your way up as opposed to match drilling a 3/16" hole. The wing damage seems minimal and the effort to replace the rib seems like it is not worth it. I am sure the Aerovee would be good for parts at least.

Edit: during the build you need to use shims between the aluminum angles and the mount. I would ask the builder if those bends were from the accident or did they try and bend the angles to match the mount better.

[Area 51%]

Looks like a bit of a stretch to call this a "prop strike".

My money is on a forward fuselage rebuild. I have an unstarted Sonex fuselage kit for sale cheap if that helps your decision making. .

[daleandee]

Not much to add to what's already been given. If the price is right it should be a great deal. You really won't know how much you have to do until you get the firewall off the front. The firewall itself may be reusable. I don't have plans in front of me either but I believe that Bryan is correct as to the attachment of the engine mount supports.

Did you check to see if the front of the fuse is still square? I also noticed that one gear leg appears to have been heated (I could be wrong) but if so was that done after the "prop strike" or was that from a previous hard landing? Can't tell much about the wings but the injury to them seems minimal.

First thing I might do is send these over to Sonex to get their take on it ...

Dale
3.0 Corvair/Tailwheel

[kmacht]

One other thing to consider since it’s an A model Sonex is if it was scratch built or kit built. You may find that if it was scratch built or an earlier kit without matched holes that you are on your own to fabricate any replacement parts. The ones you buy from the factory may not line up if the builder wasn’t extremely precise in laying out and drilling the holes. If it were me the price would have to be very very low to consider buying as you will be either reworking or replacing everything in the forward fuselage. Have you put a straight edge down the row of rivets on the wing skin to make sure the wings are straight? Inspected the spar tunnel for any sign of movement? The fact that there was some wing damage and the twisted motor mount says this was probably more than just a simple prop strike event. Like most accidents, you tend to find more damage than just the obvious once you start the repairs.

[BRS]

Buy the airframe and convert it to a -B model. Damage eliminated.

[Kai]

Oops!

If there is any doubt, there is no doubt! Either pass it up or rebuild the front to a B-model. As stated above: problem gone.

Kai
Sonex A #0525 SG TD
120HP EP915 ECI
680 hrs

[Twosblind]

Thank you all for the insight. I definitely agree it's worth pulling the firewall and inspecting everything the load could have transferred to. I feel for the price of the airplane it's probably worth doing. The airplane is kit built with all rivet and screw lines straight as an arrow so I'm not too concerned about replacement part fitment.

As Bryan pointed out, I also noticed when I was looking it over the angle aluminum that attaches to the motor mounts that they appear to be attached by machine screws where everything around them is riveted. This leads me to think that they may be reasonably simple to replace. I also noticed the shims and wondered if the bend was intentional. I don't believe they are though since you can kind of see where the two parts rubbed together prior to some kind of impact. Also the upper machine screw appears to be pulled into the countersink a little bit.

I haven't considered the B model front end conversion, that's an interesting idea. I have also emailed Sonex directly to see what their assessment of this is. Thanks again for all the input and I'll keep this thread updated with my decision!

[lgsievila]

Bryan, Twosblind,
As an EAA Tech Rep, it is what you cannot see is what concerns me. There are a whole lot of rivets that will have to be removed and that is a big task by itself. And then re-riveting will probably require rivets bigger than 1/8 " in many cases in order to have a proper fit. If that firewall is tweaked after reconstruction and you don't see that, you wont find out until you hang the engine/prop and your prop tracking is way out of spec.
Fitting a "B" model on the front would probably work provided the wings can be used. Before I started this project I would try to determine if your rebuild is enough to qualify you for a Repairman ticket so you could do your own annual inspections. I just see this as a project full of unknowns and frustrations. IMHO, it is a lot more fun to build than fix a wreck.