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PA-12 Build

Thanks Mike I’ll take a closer look :)


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I've just looked at the pics from my Mac and not my iPhone and there's loads more pics than the phone app shows and I can see there's a LOT of work gone into these!!!!!! They look EVEN more great!!!! Top work!!
 
Is this project still ongoing?

Yes, I am still plugging away at it. I installed a PA-18 seat and removed the truss. I am installing a seaplane door (right side only) and made one from cheap 3/4" square aluminum to get the dimensions and swing correct. Also to work out the hinge attachment. The new door frame was made from 6061 3/4" aluminum with rounded corners. I am currently working on a latch for it.

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I made templates for all of the interior panels except for the one behind the left D window. I also have the templates made for the lower luggage compartment.

I need to mount the wing so I can get the flaps rigged so I began working on the left wing. All hardware was removed, cleaned up and painted or powder coated. New ribs, spars, ailerons, flaps, leading edges, bows and fuel tanks (Dakota Cub) and fasteners.

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In the meantime, life keeps getting in the way of progress.

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Wayne
 

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Newish? maybe... It is dated 6 Feb 2013 on the -12 instruction sheet and 3 Jul 2013 on the drawing, and 3 Sept 2013 on the MDL STC SA02418AK.
 
Thanks for posting all these photos!! They really help me in seeing what's under the surface, when figuring out what's the fix with my own PA-12!! :)
 
There are three each side on the original gear.

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These were "before" shots.

Wayne
 

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It is now January, 2019. Progress has been glacial, but ongoing. Last entry was beginning work on the wing to settle some alignment questions with the fuselage and control cables.

I built a simple table to work on the wings. I leveled one end and used diagonal crossing strings to align the other end. I had the new spars alodined at a place in Minneapolis that does light poles and large pieces of architectural trim.

20181101_135319[1].jpg You can see the " table" in the left side of the picture here, supporting the spars. Just a piece of plywood screwed to the legs. A piece of osb ties the other end to this one.

I followed the wing assembly procedures that came with the Dakota Cub rib STC.

Dakota Cub listed the location for the ribs in their procedures. The installation of their fuel tanks requires moving some ribs and compression struts and installing a brace tube in the tank bay.

I ran into an interference issue with the tank and compression strut just outboard of the tank bay.

20181105_155417 zoom_LI.jpg The new strut supplied with the tank kit uses bolts to hold it together. The original Piper used rivets. I took the bolts out of the strut first and turned them around so the head was toward the tank (this picture) but still, I wanted more space. I replaced this strut with the one from the end of the wing (original Piper) and resolved the problem.

20181221_135942[1].jpg

I am using the Sullivan STC for flap installation. There are a number of issues related to the drawings and dimensions for this STC. The issues have been discussed many times on this site.

I assembled the flap hinges and aileron hinges and hung the flap and aileron to see how different the issue would be on this plane. I used super glue to temporarily fasten the bellcrank bracket to tape I put on the spar.

20181113_131315[1].jpg I established where the control cables entered the wing and made a cardboard template I taped to the root rib.
The green strings are the routing for the aileron controls and the orange electrical wire is where the flap control winds up. There were also issues regarding the strap locations for
the fuel tank supports. The one you see here (green) has to miss the bellcrank bracket and the wing root attach bracket on the forward spar.

I played around with moving the bellcrank up and down a bit.

20181113_132046[1].jpg 20181211_142902[1].jpg I used a small piece of baling wire to see how far I would need to deflect the control cables to clear the flap pushrod and bellcrank.

I also had to move the rib outboard about one inch to clear the bellcrank. If the bellcrank is moved lower than it is in the right most picture above, it contacts the flap hinge arm instead of the stop.
At this time, the hole is drilled for the flap hinge bracket. NOT where the STC calls out, but the spar print from the Northland cd.
Still have to get a location for the flap return springs. Think it is Mike S. who recommends two springs on each flap.

One of the newer flap STC diagrams shows a bracket used to keep the aileron balance cable off the flap pushrod. Many folks here argue that is a high drag and wear point for the cable. I agree.
I plan on using a small pulley to divert the cable. The pulley will mount to the rib adjacent to the bellcrank.

Happy new year all!

Wayne
 

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Don't forget to block the rear spar at the outboard rib for the proper twist prior to installing the leading edges.
 
a bracket used to keep the aileron balance cable off the flap pushrod. Many folks here argue that is a high drag and wear point for the cable. I agree.
I had to install something to deflect the aileron cable from the flap mechanism in my -12. I used a nylon fairlead, though with a little bit of trepidation. I did some calculations for the lateral and frictional forces between fairlead and cable and determined that the friction would be small. In practice, I was happy to find that it works just fine - my ailerons are smooth with very little friction discernible at the stick, including in flight.
 
Exactly the same story with mine. The fairlead caused no perceptible change in stick feel. If I remember correctly, the interconnect cable was rubbing the flap return spring slightly. The deflection induced by the fairlead is very small.
 
Maybe not relevant but....... one of the fairleads was missing in the aileron circuit of my PA-12, I’ve only had the plane 9 months so don’t know how long it’s been missing, but the aileron cable sized hole it was sawing through the mounting bracket was VERY scary!!!


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Maybe not relevant but....... one of the fairleads was missing in the aileron circuit of my PA-12, I’ve only had the plane 9 months so don’t know how long it’s been missing, but the aileron cable sized hole it was sawing through the mounting bracket was VERY scary!!!

Fitting the replacement meant cutting another access hole and a LOT of struggling to get the locking ring on............


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The other day I needed to install a circle clip on a fairlead in an un-handy place. I got a pair of spreader pliers with the small pins used for drilled circle clips, put them inside the fairlead clip and Voila! on it went. Gonna use them all the time now. even in a "good" place they are a pain to install with needle nose pliers or something similar.

Shiny side up!
 
The other day I needed to install a circle clip on a fairlead in an un-handy place. I got a pair of spreader pliers with the small pins used for drilled circle clips, put them inside the fairlead clip and Voila! on it went. Gonna use them all the time now. even in a "good" place they are a pain to install with needle nose pliers or something similar.

Shiny side up!

Well done!!!! We tried this, but couldn’t get the circlip pliers on to the locking ring because of the access situation :( BRILLIANT you had better luck :)


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Such a great thread. I'm buying a -12 and am new to these little old birds. This has been very helpful as mentioned before in getting my brain around how these things work. I'm a 7,000 hour pilot with much less time in the shop, so I'm excited to start learning the other side of this lifestyle : )
 
Well, I still haven't given up. The wife wanted a new kitchen, the car needed fixin, the kids needed sumpthin and then there was this little pandemic thing. I am getting close to returning to work on the -12 and have a question regarding the boot cowl. If you have read this thread, you might recall the plane was upside down from a windstorm. When it hit the ground, the engine hit hard enough to break the flywheel. The PO had patched things together and added a few "enhancements" to places that may need to be a bit stronger.

I am building a new boot cowl and found these reinforcements at the upper and lower corners shown in the photos. Have they been added or are they stock? I do know the L brackets that hold the upper and lower channels are prone to breaking and will address that during the fabrication of the new cowl.

Upper channel bracket reinforcement: 20200214_140209.jpg Lower channel bracket reinforcement: 20200214_140215.jpg
 

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Well, I still haven't given up. The wife wanted a new kitchen, the car needed fixin, the kids needed sumpthin and then there was this little pandemic thing. I am getting close to returning to work on the -12 and have a question regarding the boot cowl. If you have read this thread, you might recall the plane was upside down from a windstorm. When it hit the ground, the engine hit hard enough to break the flywheel. The PO had patched things together and added a few "enhancements" to places that may need to be a bit stronger.

I am building a new boot cowl and found these reinforcements at the upper and lower corners shown in the photos. Have they been added or are they stock? I do know the L brackets that hold the upper and lower channels are prone to breaking and will address that during the fabrication of the new cowl.

Upper channel bracket reinforcement: View attachment 52047 Lower channel bracket reinforcement: View attachment 52048

I'm not sure this Boot Cowl cracking thread matches those locations, but it does show that reinforcement of the cowl does happen https://www.supercub.org/forum/showthread.php?53353-PA12-Boot-Cowl-Cracking

Philly
 
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Yes. These are the same locations. Happens where the support channels fasten to the boot cowl. I had forgotten about that thread. Thanks.

Wayne
 
I think those are interior 'backing plates' that are what the cowling attachment brackets attach to. Be sure to check for cracks, as if you didn't know that. And I'd say yes you do need them. If you are considering a new fore wall Clyde Smith , the cub doctor, makes a very nice one, it comes with brackets that he may sell separately.
 
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