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RV-4 MS1095

MS1095

Well Known Member
I bought a local RV-4 project about a month ago. While the project is pretty far along there are some things that I'm just not happy with. I will be documenting the re-work and continuation of the build here.
 
Cowl attach hinge not to plans.





I was not happy with the riveting on the engine mount weldments and the forward fuselage skinning. The F-451 tunnels were on top of the F-420 side skin. They should be underneath. The previous builder must have forgot this step. Instead of drilling out the bottom row of rivets where the skin attached to the bottom longeron (F-450) they just drilled more holes.







 
Suggestions

I did a similar rebuild on a -4 with 700 hours of time on it. When I bought the re was significant cracking in the firewall and side skins around the lower firewall brackets. You?re doing the right thing - the lower engine mount attach brackets see a lot of stress for the landing gear, and the riveting of your old brackets would not have held up.

Here are some things I did:

I built a plywood box jig down the center of the aircraft to ensure things didn?t move. It attached to the floor structure and the roll bar mounting points, and allowed me to maintain location of the firewall, top longerons, and bulkheads.

If you don?t like the rivet lines in the #2 bulkheads, they?re pretty easy to replace while you?re ?in the neighborhood?.

Look closely at the firewall wedge to see if it was ?stretched? into place during assembly. The factory parts didn?t fit together very well, and stress during assembly will lead to cracks later. Replacing the firewall isn?t too much extra work with the sides opened up.

As originally built, my aircraft had binding and wear in the rudder pedal hinges. I found some really long AN bolts to span across each rudder pedal to eliminate the ?single shear? configuration of the short hinge bolts in the original design.

I added RV-6 style gussets to brace between the lower firewall brackets and the 3/4? angle uprights.

Good luck with the rebuild. It?s a lot of work, but well worth it!
 
1" longerons

I had to replace my longerons due to very poor bolt edge distance on the horizontal stabilizer and engine mount weldments. I used 1" angle instead of 3/4". Worked better than expected
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I built a plywood box jig down the center of the aircraft to ensure things didn?t move. It attached to the floor structure and the roll bar mounting points, and allowed me to maintain location of the firewall, top longerons, and bulkheads.

Can you elaborate? Pictures?

Thanks.
 
Considering that at this stage of the build, one should have mastered the basics of bolt hole and rivet spacing, what does the rest of the project look like?

I have two friends that are looking for RV4's right now and seeing this makes me shudder.

Hans
 
Considering that at this stage of the build, one should have mastered the basics of bolt hole and rivet spacing, what does the rest of the project look like?

I have two friends that are looking for RV4's right now and seeing this makes me shudder.

Hans

The project had 2 builders before me. You can see where the first left off and the second took over. There are some areas that need to be addressed but overall it's not a bad build.
 
Have you looked at the wing spar flanges where the fuel tanks attach? When I pulled the tanks on my project I was horrified at what I found. My spars are trash and have to be rebuilt.
 
Have you looked at the wing spar flanges where the fuel tanks attach? When I pulled the tanks on my project I was horrified at what I found. My spars are trash and have to be rebuilt.

Over countersunk?

Yes, mine look fine. I'll get more pictures later today.
 
Yikes! That doesn't look so good. Is this your second 4 project?

The only thing that gave me concern on my wings was this relief in the spar, but it is identical on both and anodized so I believe it came from phlogiston this way.

 
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Yes sir. Two RV-4 projects and two nightmares. I figured I would have learned my lesson the first time. I didn?t mean to hijack your thread, I just wanted to point out some common hidden builder mistakes that I have personally encountered. It looks like you are experienced in taking on this challenge and know what is ?acceptable? and what is not. At least Vans has excellent builder assistance and readily available spare parts. I will be following your progress and hope to see it in the air pretty soon.
 
I pulled the right side skin today and to my horror I found this. Looks like I am going to be replacing the longeron. I just don't understand how someone could do this. The rivet spacing was great right up until they drilled the mount weldment.

 
Ugly Dog Contest?

Kidding.....
actually, not kidding.
Sometimes it just seems better to say not worth it. Later it'll be your behind in the seat. How will that feel?
 
You will also need to replace those firewall angles. I don't think they are supposed to be notched. At least mine weren't. Look at the plans carefully and double check.
 
Either the second builder is guilty of extremely poor workmanship or did not realize he purchased a pig in a poke and eventually sold it to the next unsuspecting builder.

This lack of pride and professionalism in building, especially in an area as critical as the firewall is totally unacceptable and then selling it off to someone else in my opinion is unethical.

However, I must question the inspection made prior to the last purchase since most of the area is visible with an inspection mirror, flashlight and knowledge of what is acceptable in simple aircraft construction and maintenance.

I'm surprised there have been so few posts registering concern that this blatantly poor workmanship might exist in this group.

I expected better.

Hans Miesler

A+P, ATP
 
Making progress...There has been a lot to fix along the way, but it is finally starting to come together.













 
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Lower mount to vertical firwall angle gusset ?

Dont see the gusset referenced above to keep the firewall from buckling. Much easier to address before the side skin is riveted 😱
 
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