The Barn Find Build

[Eric Page]

Thanks, guys. I appreciate the info. I'll check 43.13 before I proceed. I'm a long way from needing the flaperons, so they can wait until I'm stuck waiting for parts on something else.

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I made some progress the last couple of days. I got the fuselage and vertical stabilizer stripped of fabric, and I'm glad I did. The Poly-Tack application was pretty inconsistent, so the fabric wasn't uniformly stuck to the structure. In some places it came off easily, and in others I had to pick at it with a knife blade to get an edge up that I could get ahold of.

With the tail open I can see how the ribs were done. It looks like Hysol was applied with a kitchen spatula on the end of a broom handle (it ain't pretty!), but the ribs appear to be straight and structurally sound.

Once it was stripped, I got started on removing everything. The doors came off first, then I dove into the flight control system. In all of the controls, there was ONE nut and bolt that didn't fight me. All the rest were either torqued way too tight, or had surface corrosion that made them difficult to remove, or both. I'm REALLY glad I'm taking it apart.

The rudder torque tube assembly is a mess. The pilot's left pedal and the copilot's right pedal are very tight and hard to move. It looks like the nuts holding them to the mounting brackets are too tight, so the tubes are bound up on their bushings. Unfortunately, there doesn't appear to be any way to fix it without drilling out the rivets and separating the torque tubes. The nuts holding them in the brackets just spin their bolts and won't come loose, and the bolt heads are inside the tubes and inaccessible. At least the whole assembly is off the fuselage so I can put it on the bench.

I just need to get some cable cutters and I'll be able to finish the fuselage disassembly. The rudder pedal adjustment handles are trapped because the bolts that hold the cable ends are stuck in the handle tubes, and the cables are captive in the fuselage due to Nicopress sleeves. I have an idea how to get the bolts out using some wood blocks and the bench vise, but I've got to get them free of the fuselage first.

[PapuaPilot]

I'm REALLY glad I'm taking it apart.

That is what you want to say after wondering if total disassembly was the right thing to do.

As far as you rudder pedal issue I would search the forum on this subject. Look especially for the people who did a build log. This is a known problem and it usually takes us several days of work to align, trim, shim, and mount the rudder pedals and get them free from binding. There is a good chance this wasn't done properly at the original build. Now is the time to take care of it.

[Eric Page]

As far as you rudder pedal issue I would search the forum on this subject. Look especially for the people who did a build log. This is a known problem and it usually takes us several days of work to align, trim, shim, and mount the rudder pedals and get them free from binding. There is a good chance this wasn't done properly at the original build. Now is the time to take care of it.

When I discovered the problem I thought it must be a misalignment in the way the brackets were mounted to the fuselage, but the assembly is still very stiff even after it's removed. I need to look at the assembly and fitting procedure in the manual to understand how it's supposed to work, but it sure looks like the bolts/nuts that attach the torque tubes to the brackets are too tight.

Like the flaperons, fixing this will wait awhile. Primary focus for now is getting the fuselage ready to go to the welder for tail reinforcement and additional mounting tabs for avionics and antennas. The disassembled rudder torque tubes will go as well, for gusseting.

[Dave S]

Eric,

It is not that rare that people have some fitment issues with the torque tube mounting. If the original builder did not remove enough material from the hard plastic bearing that could be the issue.

Your comments about encountering bolts that were over tightened may be an issue; but, realizing that the bearings are inserted after the bolts are tightened to the mounting part would seem to indicate that the bigger problem with them sticking may be the fit in the first place.

If a person follows the procedure in the build manual for turning/filing/sanding the bearings down to fit that should alleviate the problem. I found that mounting the bearing on a bolt chucked into the drill press made it easy to turn them down. I also found that working the bearing into a slight barrel shape by taking a bit more off the ends of the bearing while keeping the fitment at the center very close helps a lot with whatever misalignment may be present.

It is not beyond possibilities that if the assembly sat for a while there may be some light surface rust inside the torque tube at the bearing end that may be interfering.

You'll get it figured out.

[alexM]

Yes, those outboard bearings with the hidden bolt heads should pull right out of the tubes. The bolt isn't some kind of chinese finger puzzle.

[Eric Page]

Excellent, thanks for the tip, Alex. I'll give that a try tomorrow and see if the bearings will pull out of the torque tubes. And Dave, I appreciate the tip on fitting the bearings for smooth operation. I'll refer back to this when the time comes.

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I finished disassembly of the fuselage today, after having the light bulb come on over my head with the idea that I didn't need cable cutters to get the control cables out -- I could use the Dremel! The cable made short work of the first cutting disc, so I switched to a 4-1/2" angle grinder, which did the trick. That freed the rudder pedal adjustment handles, which had bolts holding the cables in place that were stuck. I put them in the padded vise jaws, applied a little penetrating oil and gave them a few taps with The Persuader, which broke them loose.

I also removed the flap handle and center console, which completed disassembly of the flight controls.

Finally, I pulled off the brake calipers and found that they had significant surface corrosion, some of which appears to extend into the cylinders. If anyone has an idea how to get the pistons out of these things, I'd be thrilled to hear it. I want to check the cylinder bores and pistons, and at a minimum, replace the o-rings.

[Dave S]

Eric,

The calipers are pretty expensive so it pays to go slow and get it right the first time.

WORD OF CAUTION - FIRST

The normal way of getting the pistons out carries with it a risk of creating a 40 millimeter cannon which you don't want to have any body parts in the way as well as some risk of damaging the parts if done incorrectly.

So we do it carefully.

Applying air pressure to the line going into the fluid chamber is how these things are normally removed. USE ONLY VERY LOW AIR PRESSURE APPLIED WITH AN AIR GUN - no more than 5 psi at first and only increase a little at a time as needed to get it to move.

1) Have some type of retaining clamp (C clamps often used) to prevent the piston from getting away but you need some give in it so use some foam, rag or similar between the clamp and back side of the caliper - doesn't have to be tight but you need to assure the thing doesn't come flying out. The clamp is loosened as the piston comes out.

2) Since there is some surface corrosion that may interfere with smooth extraction - its good to remove what corrosion you can first - then be prepared to alternately apply air pressure and press the piston in to work it loose. This may be your biggest test of patience.

3) If the piston comes out part way and seems to stick - do not be tempted to grab it with a pliers! Just keep pushing it in and out with you fingers and air pressure to work the gunk out and allow the piston to come out.

Normally the pistons come out with very little problem and just a little air pressure. The corrosion may make them a bit sticky.

Good luck and be careful.

[Eric Page]

Thanks again, Dave. I'll try your method next time I'm working on it. I'll be away for a few days, but should be back at it by the middle of next week.

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I had a nice visit this morning from fellow Series 5 builder Alex (alexM of Project 5), who flew down with his son in his Citabria. He gave my project a good look-over and offered some valuable advice on a couple of things. He also generously gave me his eight leftover rudder torque tube gussets, so I won't have to fabricate those. Thanks, Alex!

Today I re-built a couple of sawhorses from the remains I got with my kit, then put the fuselage on them and removed the landing gear and tailwheel. I found two of the four landing gear bolts missing cotter pins, and a third that was installed but not bent around the nut.

I drilled out the rivets in one end of my dented elevator push-pull tube, which freed it from the fuselage. On Alex's advice, I used some heat to try to remove the reducer from the end of the tube. I kept increasing the temperature until I had the heat gun on maximum and the adhesive began to change color, but it wouldn't budge. When it got to the point that I was damaging the reducer in the attempt, I gave up. Alex mentioned that SkyStar used to use another (3M?) adhesive that doesn't soften with heat before later switching to Hysol, so maybe that's what I've got. Anyway, I'm sure Kitfox will be happy to sell me two new push-pull tube reducers. The rod end bearings look new, so I'll keep those.

While Alex was here, he showed me how the bearings in the rudder torque tube come apart (we tried briefly to pull them out, but couldn't do it). I put them in the bench vise and tried to pull, then knock them out, but all I was doing was dragging the bench away from the wall! The original builder must have pressed them in (I did see a hydraulic press in the trailer with the plane). I had to resort to using a flat blade screwdriver and a rubber mallet. Three out of four came out cleanly, but one was damaged around the flanged end, and I found a Grade 5 hardware store bolt and nut holding one of them to its bracket. Have I mentioned how happy I am that I decided to disassemble this thing?

Now for the bad news: I found that two of the lower fuselage tubes are bent. They're both at the same "station" in the plane, between 30" and 51" aft of the wing strut attach point. The bends are pretty gradual, over several inches and without any kinks, so I think they're fixable. It looks like the original builder must have let the plane sit (or drop!) on a sawhorse in the middle of the tubes' span. I'll have to build a straightening tool like what 109JB used, here. I also plan to go through the entire plane with a straight edge to be sure there aren't any more surprises!