STC, 337s for cessna 170

[Francis Cahoon]

Does this Association have any copies of STCs, 337s, for Cessna 170s and if they do, how do I research them or obtain them. For example larger tires.

[canav8]

Yes, and you must become a member. Join the TICA 170. It costs $45/yr. The information you have received to this point already paid for itself. I am just saying. Can you put a price on this resource. Of Coarse you are thinking free but who has to pay to keep this website running? Get the Idea? D

[Francis Cahoon]

Thank you Aryana and Dave for your replies. Aryana your answer to my question was just what I needed. I am new at this stuff, and just learning to use all this fancy computer stuff. I do intend on joining the association, although I dread having to fill more stuff out, so it might take awhile, but thank you. Doug thanks for your response, I do not think we have ever met, therefore, I do not believe you have anyway of knowing how I think. Your statement that I was looking for these 337s, STCs for free is in correct. I do not have any knowledge at this time on how I might obtain them, therefore my questions. I am the kind of guy that says what he means and means what he says. My phone number is Four Oh Six -261 7046, if you would rather talk to me by phone. Again thank you guys for responding. F Cahoon

[Francis Cahoon]

Aryana, I just looked at the web site or whatever it is called. It is exactly that I was looking for. Thanks again for sharing your knowledge. I am very impressed with all the info. I commend the Assocation, and who ever put all the time and effort into making said Assocation such a place of knowledge, and accessable to guys like me. THANKS. F Cahoon

[Bruce Fenstermacher]

Your statement that I was looking for these 337s, STCs for free is in correct.

Francis, please don't take offense of Dave's statement. I personally look for as much FREE stuff as I can find on the web. If someone or some entity is willing to create and share the resource for free. Of course I know it is not free.

Another tip since you are new to fancy computer stuff and forums. Many times the written word, special those written by average folk, not professional writers, is seen as an attack by the reader when the writer had no intent. There just isn't the same reflection of voice or body language to help interpolate the message. For example, perhaps you were not that upset by Dave's comment.

[Bruce Fenstermacher]

Francis, I remember there are a few 337s in our library for larger tires. But they aren't likely to do you any good. 337 just don't have the weight they once had to get new approvals. And any STC paperwork won't help other than for research because you don't have the STC holders permission to use the STC.

There are several threads about larger tires. Greg (bigrenna) has done a pretty good comparison of the differences. I can not recall if he commented how much the take of roll decreased, if any with the increased angle of attack the larger diameter tires gives.

I searched bigrenna and tire and come up with these threads which probably have some info your looking for. I'm sure there are others:

http://www.cessna170.org/forums/viewtop ... ire#p90311
http://www.cessna170.org/forums/viewtop ... ire#p94614
http://www.cessna170.org/forums/viewtop ... ire#p90526
http://www.cessna170.org/forums/viewtop ... ire#p89544

[Francis Cahoon]

Thanks Bruce, since my last post I have acquired a set of goodyear 26x10.5x6 tires. I also found a copy of a 337 dated 7-27-2009 that approved said mod. I am slowly learning this process of making these mods legal. Very time consuming. Thanks again, Francis Cahoon

[Bruce Fenstermacher]

Thanks Bruce, since my last post I have acquired a set of goodyear 26x10.5x6 tires. I also found a copy of a 337 dated 7-27-2009 that approved said mod. I am slowly learning this process of making these mods legal. Very time consuming. Thanks again, Francis Cahoon

But that 337 you found doesn't approve the mod for YOUR plane. So you can not use it as approval to install these wheels and tires on your plane. The existence of the 337 your found is interesting at best. It means that someone at some time received approval from the Feds to install them on their plane and perhaps you could find someone to do the same for you. Good luck. These types of approvals are all but non existent today.

[Watkinsnv]

AC 23-27

[n3833v]

AC 23-27
http://www.faa.gov/documentLibrary/medi ... _23-27.pdf

[Bruce Fenstermacher]

From page on of AC23-27:

• This advisory circular (AC) provides guidance for substantiating parts or materials substitutions
  to maintain the safety of old or out-of-production general aviation (GA) aircraft, or other GA
  aircraft where the parts or materials are either difficult or impossible to obtain. This AC also
  provides guidance about the data required to gain Federal Aviation Administration (FAA)
  approval for making these substitutions.

Francis has focused on larger tires. The purpose of AC23-27 is to substitute like parts not specifically approved. It is not to modify an aircraft. Using it to gain approval to install larger tires than what was approved is outside it's scope in my opinion.

[Watkinsnv]

(4) You may use previously approved (per STC or field approval) part/material
substitutions on like-type aircraft. If the part/material is installed with previously approved parts
or material, PMA, technical standard order (TSO), NAS etc., and if it is completed in a similar
manner consistent with a previous field approval or STC, you may use those approvals as the
basis for approval on your aircraft. However, if you want to use a previous field approval or
STC as the basis for approval on your aircraft, you must have all the previous field approval or
STC data, including any instructions for continued airworthiness, or develop any missing data
through support from an appropriately authorized DER or ACO approval and permission from
the STC holder (14 CFR parts 21 and 91, §§ 21.120 and 91.403(d)).

[Francis Cahoon]

Thank you guys. I am finding it very hard to find the right info. At present time the FAA guy is being very helpful. With any luck I might be able to use my (good deal) tires that I purchased. Thanks again Francis

[GAHorn]

Emphasis on: " However, if you want to use a previous field approval or
STC as the basis for approval on your aircraft, you must have all the previous field approval or
STC data, including any instructions for continued airworthiness, or develop any missing data
through support from an appropriately authorized DER or ACO approval and permission from
the STC holder ..."

Most 337's do NOT include such supporting data.

[Francis Cahoon]

Thank you gahorn, I currently have the papers that you had mentioned earlier. Those being, one major repair and alteration, one work sheet for tundra tire installation, one description of work accomplished, and new weight and balance calculations. The FAA guy has been very helpful, I am taking all the stuff to my IA tomorrow. Oh and the tires have to have a TSO number also. Hope this helps anyone looking to put bigger tires on their 170, and I would be willing to help anyone else thinking about this type of mod. Thank you. F.Cahoon