The International Cessna 170 Association

Doing some long range planning for our '48 170 and thinking about adding the additional 12 gal fuel tank. Anyone able to get me started in the right direction?
Marc

How long do you want to sit without moving? 3 1/2 to 4 hours is enough for me. I can do also without the extra weight.

John

Marc,
I assume you are talking about an additional tank in the left wing. As you may know adding a Javelin aux. tank in the baggage compartment is approved in the TCDS. Do a search on this website and you'll find several threads on adding an additional tank in the left wing. For example, in this thread you'll find that Dick Mansfield and Steve Grewing both have the additional tank in the left wing. In this thread several guys offer to help with data on the installation of a fourth tank. That thread mentions a one time STC869NW which Bruce has filed as #79 in the Maintenance Library. This STC may have been surrendered as I no longer find it listed in the FAA's database. In the FAA database however, I found another one time STC, STC SA02034NY. There is also SA733WE for a 12.7 aux. tank in the C-170. This is dated Jan. 1, 1960. Good luck finding information on that. You would have to follow guidance in this document to get data/drawings from the FAA using the FOIA. In the good ol' days one could submit someone else's 337 form and use that as a basis for getting a field approval for your plane. Those days are long gone. It is nearly impossible to get a field approval these days. What you need is not just what the FAA terms "acceptable data" (which is what someone else's 337 might be) but "approved data". And that is what is golden about the last entry in that last thread I linked. Jim's 337/field approval is dated July 1952. ANY 337 WITH A DATE PRIOR TO OCT. 1, 1955 IS CONSIDERED APPROVED DATA BY THE FAA. Your mechanic can use that as a basis for installing a fourth tank. No approval from you local FSDO is necessary.

Hope this helps with your "long range" planning. Good luck on the project!

n3833v wrote:How long do you want to sit without moving? 3 1/2 to 4 hours is enough for me. I can do also without the extra weight.

John

John, as hard as I’ve looked, I’ve never found an FAR that says you have to take off will all tanks filled, or that if you do, you have to burn all usable fuel in one leg. Sometimes it’s nice to be able to do a round trip without refueling, due to either cost or availability. Or sometimes you unexpectedly find that you can’t get fuel at your planned stop. If I had a ragwing, I’d want the 4th tank.

Marc, you might contact Duane Shockey in San Diego. He has a ‘48 with 4 tanks, but I don’t know if he bought it that way or had it done. His contact info is in the directory. Phone is probably the best way to contact him.

Marc, I am restoring a 48 with wings I acquired that have the fourth tank. I have drawings and paperwork previously approved which I plan to advance for approval on my aircraft this summer. You may email me if you prefer at melcessna@indy.rr.com and we can discuss further. Best, Mike