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PA 12 Want to add Flaps

I'm currently buliding up a set of PA-12 wings in which I'm adding the Dakota Cub flap kit via Ron Sullivan STC. I've got the kit but have not recieved the STC yet.

Can someone tell me or show me a picture of how/where the flap bellcrank return spring attaches to the spar?

These wings are still using the standard PA-12 tanks.

Ryan
 
The spring hooks into a tab that's bolted to the spar web. My IA told me to position it so that the spring is stretched an inch or two longer than the print shows, to help the flaps hold their up position.

You'll want to temporarily rig all of the cables (including aileron cables) and pulleys and bellcrank before drilling or welding and carefully check clearances at all control surface positions. The STC prints result in some interferences.
 
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Yes : What Gordon says. I installed my springs as per the prints---turned out spring tension was WAY too wimpy in that location. Seems I read some info here on dot org where some even double up on the springs (2 springs) so when parked and encounter wind gusts on the tail the flaps are not getting hammered. geezer Dan
 
I'm currently buliding up a set of PA-12 wings in which I'm adding the Dakota Cub flap kit via Ron Sullivan STC. I've got the kit but have not recieved the STC yet.

Ryan

not sure if it's that STC, but one of the -12 flap install blueprints has you put the flap hangers in the wrong place/height wise attached to spar/cable interference or such?.... sanity check yourself before drilling the 3/8" holes

i usually put 2 springs on each bell crank...
 
Ryan, I highly recommend if you have stock tanks upgrade to Dakota 24 gallon tanks at the same time.

Dakota parts are very nice to work with.
 
As I recall (it's been a few years) Mike is right about flap hangars. At that time I spoke with Mr. Atlee Dodge and he sent me a template for the hangar location. Be sure to double check their location before drilling. Installing flaps was the biggest challenge of the rebuild for this old guy but have been very happy with the results.
 
just finished my flap install. I used Ron Sulivan's STC and bought all the gear from Dakota Cub. Nice stuff and the install was pretty straight forward. The STC shows a bracket to keep the aileron cable supported clear of the flap actuator and shows a part number..., it's phony and you have to have it, so make something yourself. Sullivan's set-up adds longer flaps and moves the ailerons further out on the wings, so there's a lot of work involved. If you want to stick with regular size flaps, Univair has a kit for that. If you are going to keep your front seat as is (with the truss work), I think Sullivan's STC covers the flap handle install on that as well, but if you are thinking of changing to a PA-18 front seat (removing the truss work) then Atlee Dodge has finally completed an STC for that so you can mount the flap handle easier.
 
Got to the point to hang the wings to hook up the flaps for a dry fit before cover. The bellcranks were placed at the top of the spar close to the cap as possible as per the Dakota Cub blueprint and photos of other installations. The problem now though is the aileron cables rub against the bottom of the flap bellcranks. I'm not really sure how to remedy this and was curious as to if anyone has encountered this and has a fix for it? Some initial thoughts of my own on it were to install a smaller diameter pulley where they exit the fuselage by doing this the cable would run lower up to the first fairlead and hopefully clear the bellcrank. Any ideas will be greatly appreciated. Ryan
 
Got to the point to hang the wings to hook up the flaps for a dry fit before cover. The bellcranks were placed at the top of the spar close to the cap as possible as per the Dakota Cub blueprint and photos of other installations. The problem now though is the aileron cables rub against the bottom of the flap bellcranks. I'm not really sure how to remedy this and was curious as to if anyone has encountered this and has a fix for it? Some initial thoughts of my own on it were to install a smaller diameter pulley where they exit the fuselage by doing this the cable would run lower up to the first fairlead and hopefully clear the bellcrank. Any ideas will be greatly appreciated. Ryan

not that i did this to redirect cable(Day & Night flap mod..not familiar with Dakotas..), but mores to keep the soft 7x19 cable from sagging onto the hangers(original had that harder cable), but you might be able to get what you want doing this... top view, block of ski bottom type plastic.. phenolic would work too... or use a real piper fairlead...
IMG_1054.jpg
 
Geezerhood causes memory issues. Seems I recall using Piper fairleads to guide cable ( had to build brackets ) Seems I remember an A&I saying it was O.K. as long as the deflection did not exceed 5 degrees. My Ailerons are VERY smooth and many who have flown my old beater have commented on that.
 
pix of my project and Ron Sullivan's drawings.
 

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I had Univair build me a set of 14 wings and there were some special brackets used to solve your problem.

If I were you, I would give them a call and get a set of their 14 wing drawings, which shows the parts and placement of everything.

They may be able to sell you the parts you need to make what you have work.

Everyone should note that Univair's 14 flap installation has better, accurate drawings as opposed to those that are associated with the 18 flap mod STC.
 
I had to use a standard fairlead to make the aileron cable clear the flap mechanism. Then installed an inspection cover to be able to inspect / rotate / replace the fairlead plastic if necessary. My ailerons are nice and smooth. I don't think you want a smaller pulley on the fuselage, due to possible cable fatigue issues. Sorry, I don't have any photos of that.
 
The kit includes everything except flaps. PA-14 flaps are different then PA-18 flaps. I have blueprints for PA-14 flaps. Had Airframes Inc make a set off my blueprints when I rebuilt mine.

Crash
 
Thanks everyone for the replies. I think there must be more than one Day and Night STC, the one I'm using, STC SA578AL uses a standard lenth PA-18 flap with the bellcrank/accuator at the inboard flap hangar same as a PA-18.

I started the project using the blueprint that Dakota Cub supplied with their PA-18 flap kit which has you place the bellcrank at the top of the spar cap. I assumed (yes I know what happens when you assume) that the Dakota kit was used in conjunction with STC SA578AL all of which was being supplied to me by the owner of the aircraft but now I'm not sure the Dakota kit is particular to any one STC. I'll be calling Dakota Cub and Ron Sullivan Later today.

Gordon, I had those same concerns with a smaller pulley. I'm thinking the route to go will be a type of fairlead arrangment to keep the cable away from the bellcrank.

Thanks,

Ryan
 
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I would be happy to show anyone my new uncovered Univair PA 14 wings. They are located in Springfield Illinois.


For those of you who might be considering adding flaps to a 12, it might be worth it for you to take a drive down and see them for yourself.


Best wishes,


Paul Heinrich
 
As you can see, I used the Ron Sullivan STC but I too got the flaps and hangers from Dakota Cub... when I ordered everything I told them I was using Sullivan's plans and everything fit pretty well. Those are some really long flaps!
 
Paul,

How about posting a handful of pics? My car is froze in, so getting to Springfield is not in my near future. Ones that would be particularly helpful would be of the rear spar in the bellcrank vicinity to see how Piper addressed the interference of the aileron cables vs. the bellcrank.

BES posted some pics of his flap crank install here http://www.supercub.org/photopost/showphoto.php?photo=18549&cat=500&ppuser=156

My prints of the flap installation (SA578AL) don't include the block to redirect the aileron cable. The signature block is totally different than the pic in av8rtom's post.

Has anyone posted pics of the marden prints yet?

Wayne
 
Wayne, that's the same STC I'm using. I can post some pictures of it soon. I think I've got a pretty good solution for the forward aileron cable/bellcrank interference by using an additional fairlead off of the inboard flap hangar on the same order as the pics Mike S. posted earlier in this thread. As for where the rear aileron cable interferes with the accuator I think I'll go with the same thing as in the pics posted by av8rtom.

Another issue I've encountered with this project is the rear aileron cable rubs (ever so slightly) on the rear false spar brace of the ribs. These are Dakota Cub PA-12 ribs. I'm now either faced with making new fairlead pieces on the ribs or notching all the rib braces. This issue has nothing to due with the addition of the flaps and is more an issue with the ribs.

Has anyone else had this problem with Dakota ribs and if so what did you do to fix?

Thanks,

Ryan

Agian, I'll try and post some pictures soon.
 
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Here our some photos. We were able to make a fairlead bracket the bolts to the inside of the inboard flap hangar that keeps the cable out of the bellcrank. I'll still have to make another fairlead for the forward cable where it hits the accuator with full flaps pulled. The aileron cables are no longer rubbing on the rib braces when tensioned.

Ryan
 

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Another issue I've encountered with this project is the rear aileron cable rubs (ever so slightly) on the rear false spar brace of the ribs. These are Dakota Cub PA-12 ribs. I'm now either faced with making new fairlead pieces on the ribs or notching all the rib braces. This issue has nothing to due with the addition of the flaps and is more an issue with the ribs.

Has anyone else had this problem with Dakota ribs and if so what did you do to fix?

I used Dakota ribs on my 12 also, and had to relieve rib gussets. I used a die grinder to make a rounded contour for the cutouts.
 
Thanks for the pics, Ryan.

The Pacer uses fairleads like that on the hinge for keeping the cables tidy.

Wayne
 
These photos are from the new PA14 wings I bought from Univair.

They show how Piper solved the Flap/Aileron control cable clearance issue that arises when Flaps are installed on a 12/14 wing.

Note the brown triangular phenolic standoff inserted on the rib to provide separation clearance between the Aileron control cable and the Flap Bellcrank and the spacers attached to the Bellcrank itself, which provides clearance for the Flap return spring doohickey.

I also received an original PA14 wing drawing from Univair that shows the part numbers and installation details, so anyone who wants to install 14 (or 18 Flaps) on their 12 can get one from Univair for guidance.

In my opinion, 14 Flaps are better than 18 Flaps on a 12 for a number of reasons: they are longer, the wing attachment and actuator attachment points are wider and better centered, they were designed to fit the 12/14 trailing edge, and, it seems to me, that Piper chose this design, rather than the 18 design, for a reason and who am I to question their engineers.


I'll bet, too, that the guy who got the 18 Flap on a 12 STC chose 18 flaps rather than 14 Flaps because he had a set laying around or knew they were readily available because Piper was still making 18 Flaps, not because they were a better design for a 12.

I hope this helps.


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