I am about to recover my super cub wing and told the A&P to take off my Xwinds STOL CONCEPT tips and put on Dakota Cub tips. He said he didn't think we could do that as those CONCEPT tips were part of the original wing modification of squaring off the wing and lengthening out the aileron, he thought. Surely I could do that I would think, but how? I really want to keep my squared wing with the longer aileron and then add my Fowler flaps. I think it would be a hecka of an overall good mod and performer. And we could use a few good Piper ribs and where might I find those bad boys? Thanks for any help I can get on this "holding me up" paperwork issue.
Modifying my super cub squared wing's tips
- Thread starter The Kid
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mike mcs repair
Registered User
chugiak AK
Not ALL parts of an STC mod need to be installed. Up to the installer for/mechanic. For example we had a citabria with a crosswinds stol fences, but no cuff, paper work time at sale cleanup and FAA said that’s fine just log it as part of stc...
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RaisedByWolves
FRIEND
Tx
You can also extend the flaps inboard. Part of the stc, you don’t have to have the rest installed.
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I have 40 years of paperwork and we just found an STC that would allow me to do that and put Sullivan tips on. I really would like to go Carbon Concept tips or Dakota Tips. Does anyone know of any paperwork, field approval I guess, that would allow me to go from Sullivan tips to Carbon or Dakota tips?
mike mcs repair
Registered User
chugiak AK
I think you(your mechanic..) is making this harder than it needs to be....
I have in the past gotten field approvals to put a dakota style copy tips on when Sullivans were called for(sullivan had a weird multi STC's of THEIRS required thing, my FAA inspector just shook his head about..)... but that was back when it was EASY to get field approvals, I think it's pretty relaxed now, and unnecessary....
I have in the past gotten field approvals to put a dakota style copy tips on when Sullivans were called for(sullivan had a weird multi STC's of THEIRS required thing, my FAA inspector just shook his head about..)... but that was back when it was EASY to get field approvals, I think it's pretty relaxed now, and unnecessary....
I had a FSDO inspector tell me one time... "It's OK, we don't care what you do with your wingtips because it doesn't make that much difference.. you can write it in as a minor alteration." When I was a young guy I watched a hangar door come down on a 172 with droop tips. They put an "original style" (pre '72) tip on that side (only tip at the airport) and took it out and flew it.... stalls, etc. The old guy (whom I love, Is long deceased, soloed me, and is a God in my view) said he couldn't tell the difference.
I dunno, not trying to sell anyone on anything but I do remember those things.
Also, one of the survey guys I know has a Cub with simply blunt last-rib tips.. that one gets off faster than any of the others I've watched... kind of like an Ag Cat. He didn't waste the weight on any fancy lift-enhancing devices out there.
The Rutan quote..(I believe) of - " If you let it go and it doesn't rise it's too heavy" applies I think.
Also that part about whether it lifts it's own weight plus some...
FWIW, when I put my Cub back together (apart for rust long ago - not bent) it's going to have the original tips - I doubt any of the changes make a sweeter wing.
I dunno, not trying to sell anyone on anything but I do remember those things.
Also, one of the survey guys I know has a Cub with simply blunt last-rib tips.. that one gets off faster than any of the others I've watched... kind of like an Ag Cat. He didn't waste the weight on any fancy lift-enhancing devices out there.
The Rutan quote..(I believe) of - " If you let it go and it doesn't rise it's too heavy" applies I think.
Also that part about whether it lifts it's own weight plus some...
FWIW, when I put my Cub back together (apart for rust long ago - not bent) it's going to have the original tips - I doubt any of the changes make a sweeter wing.
Denny,
Possibly. I met you up there when I was at the AK. Av meeting in May too. I looked at your plane. Remember me? What is CAC? Do you mean Carbon Concepts? I like his stuff. BUT I may just cap them off; I don't know yet. Those tips I have weigh, I think, about 14 lbs each? I really am not familiar with the Sullivan tip and how it looks and performs next to a Dakota Cub tip. I think, if I could do anything and wanted a tip over just capping it, I would prefer a DC tip made by Randy in carbon fiber.
mike mcs repair
Registered User
chugiak AK
CAC and carbon concepts are same family. Different businesses
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Owner produced parts need to comply with the Type Design. He can’t change the design as an owner produced part.
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Only if the STC makes that provision. If an STC doesn’t explicitly say portions can be installed, then the entire STC needs to be installed, or you need an additional approval (Field Approval, DER Approval, one time STC) to install piecemeal.
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bob turner
Registered User
That would have been my guess. One fed told me that a field approval had to be followed exactly, and made me specify a particular brand of hose. I got that changed before block 3 was stamped.
The strange thing is you can install two different STCs, and no fed has to approve, even if they have differing effects. I learned that when a buddy put micros on a Sportsman leading edge. They just measured from the new leading edge.
The strange thing is you can install two different STCs, and no fed has to approve, even if they have differing effects. I learned that when a buddy put micros on a Sportsman leading edge. They just measured from the new leading edge.
Denny,
I would possibly trade my Center tips for your Sullivan tips but I would have to have my A&P OK it as "legal"(so any paperwork you can supply me on your tips would help) and the tips would have to be in pretty good shape as I am putting in all new wing parts and want a first class job (which I am getting and then some). I am trying to knock at least 75 lbs out of this plane so the carbon fiber route is how I would like to go if my A&P can come up with the legal paperwork to do this. Again, also looking at just "capping" the ends which I have never heard of (probably the lightest thing I can do). Like I said before, I have 40 years of paperwork and many "Alaskan" mods for my mechanic to go through and see what all of our options are.
I would possibly trade my Center tips for your Sullivan tips but I would have to have my A&P OK it as "legal"(so any paperwork you can supply me on your tips would help) and the tips would have to be in pretty good shape as I am putting in all new wing parts and want a first class job (which I am getting and then some). I am trying to knock at least 75 lbs out of this plane so the carbon fiber route is how I would like to go if my A&P can come up with the legal paperwork to do this. Again, also looking at just "capping" the ends which I have never heard of (probably the lightest thing I can do). Like I said before, I have 40 years of paperwork and many "Alaskan" mods for my mechanic to go through and see what all of our options are.
mike mcs repair
Registered User
chugiak AK
not according to our FAA...
cubpilot2
SPONSOR
Anchorage Alaska
I got rid of the plane booster droop tips, extended the ailerons
and finished it with the existing plywood rib.
Works great. I did get a field approval at the time.
You have to end the wing somewhere. It doesn’t have to be “fancy”.
and finished it with the existing plywood rib.
Works great. I did get a field approval at the time.
You have to end the wing somewhere. It doesn’t have to be “fancy”.
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john schwamm
SPONSOR
Anchorage, Alaska Carefree, AZ
I am having some new tips made by the Airglas people in Anchorage same as the one Carbon Concepts make but far better quality. I have a set of theirs and they just do not lay down to fit right at rib, just a bit too flimsy and warped where screws go on the inboard edge.
Ones I will have should be complete next week.
Advise if anyone wants a set. Not priced yet.
What would a nice quality set be worth? Carbon fiber and light, will see weight next week.
Going on a Husky, but same as Cub rib.
John
Ones I will have should be complete next week.
Advise if anyone wants a set. Not priced yet.
What would a nice quality set be worth? Carbon fiber and light, will see weight next week.
Going on a Husky, but same as Cub rib.
John
Every STC has a limitation that says the Installer is responsible to determine that the interrelationship between this STC and any other previously approved modifications will induce unairworthy characteristics. There is even an AC that helps you make that determination.
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There in lies the problem, no standardization between FSDOs, and even between inspectors in the same FSDO
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hotrod180
FRIEND
Port Townsend, WA
That's my understanding also.
Or at least how it should be interpreted IMHO.
Installing two different STC's that may interact is NOT the same as installing only part of an STC.
that is no problem. Because one mans junk is anothers treasure. I think i said that the right way? were all individuals and if everything was done according to one mind this world would suck.
So does this boil down to the fact that if I want to add a wing tip, that isn't in any of my STC paperwork, then it's either a "minor alteration", and A&P determined (and needs no approval) or I have to get a "field approval",by the local FSDO folks? Same with just "squaring the wing off" with no tip at all, which I think is a great idea too and doesn't weigh sicum? I think supercub.org is a fantastic site; I should have been using this more over the years because of the quantity of "experience" out there to help each other figure things out. I like the education part of it and "ideas" (I never thought of that) part of it. Thanks!
mike mcs repair
Registered User
chugiak AK
yes I remember asking my inspector if i could do something some one else 's fat said they couldn't(same office) and he was like "yes, but don't get me into a debate with the other guys in the office...."
key thing is to ask for right guidance, then NEVER ask again once you've gotten the right answer you need!
And get it in writing or email! I’ve seen lots of times when a violation gets issued, without paper or email from official source, the response will always be “I never said that”!
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bob turner
Registered User
DGA has the idea. Granted, a lot of paperwork never gets looked at - we have really high power approved repair stations that routinely skip ADs on annual. One Mooney went for twenty years without fuel tank or control column AD compliance. Another doesn't do the Champ DMB wheel AD. And I mentioned the Cub muffler AD missed by three different shops (I insisted on an Atlee Dodge muffler - I hate doing that AD on a Super Cub).
So a fed says "minor" (by the way, modify a wing rib and it is not "minor"). Then change address and IA. On the minuscule chance that your new IA even spots it, you could be in for an expensive "un-modification!
I really like the less extreme wingtips, shown above. We do have a Super Cub here with those giant droops. Nobody likes them. Dakota makes reasonably good looking tips. I have no idea if modified tips do anything for a Cub. They usually hang them on after 200# of other kitschy mods, so performance is down from the get-go.
So a fed says "minor" (by the way, modify a wing rib and it is not "minor"). Then change address and IA. On the minuscule chance that your new IA even spots it, you could be in for an expensive "un-modification!
I really like the less extreme wingtips, shown above. We do have a Super Cub here with those giant droops. Nobody likes them. Dakota makes reasonably good looking tips. I have no idea if modified tips do anything for a Cub. They usually hang them on after 200# of other kitschy mods, so performance is down from the get-go.
BC12D-4-85
SPONSOR
Fairbanks, AK.
Charly at Crosswinds told me years ago that his dad Cal started with a flat flare to his wingtips. Then he kept bending the rear down until it helped performance. Finally he needed to add the upper fin to maintain the curved shape under windloads. Someone should confirm that but whatever worked was the bottom line. Great times then to be an experimenter which they both were and are.
Gary
Gary
