The International Cessna^® 170 Association

I found a new bulkhead that is on its way from Corvalis, OR. I riveted the door post bracket in today, except for a few - a very enriching experience and hope to get the wing back on this week. All that is left now is copying the far aft tailskin that was cracked on each side right at the top line of the tailwheel bracket, and reinstalling it. It isn't easy finding .032 at a decent price, plus shipping, but I managed to find a piece here nearby. Does anyone have any good advice on forming the conical shape of the bottom? The tail radius is much smaller than the end attaching to the 2nd bulkhead. Any tips on how to create a very accurate template? I made one out of a thin cardboard, and it's ok, but I feel it could be better.... Thank you, Shawn

Shawn,

You said you drew this up in CAD, correct? I'd see if I could find a shop locally to laser or water jet cut it for you.

Not sure Shawn but I think you're asking how to form the bottom skin and specifically the aft end of that skin?

Ryan,
I was able to find a new part for the bulkhead. I will draw the part in ACAD, but later.
Yes Jim, my question revolves around how to form the skin of the last station, once i have the panel cut out. One end's radius is larger than the other. It's not a simple bend, like a leading edge, for example.

Best solution is to find/beg/borrow access to a sheet metal roller. A lot of community colleges or vocational schools still have metal working shops. They even probably have folks who know how to use the roller.

Word of caution, it can be an expensive learning curve to try and just figure it out. But, the tighter you adjust the rollers, the more pronounced curve you will get. To get different radi, one side needs to be tightend more then the other. Start slow, use multiple passes, and practice on scrap if you can find it.

Also, make sure the rollers are clean and don't have any dents or burrs... don't ask me how I learned that ...

Hope that helps.
Chris

spduffee wrote:I found a new bulkhead that is on its way from Corvalis, OR. I riveted the door post bracket in today, except for a few - a very enriching experience and hope to get the wing back on this week. All that is left now is copying the far aft tailskin that was cracked on each side right at the top line of the tailwheel bracket, and reinstalling it. It isn't easy finding .032 at a decent price, plus shipping, but I managed to find a piece here nearby. Does anyone have any good advice on forming the conical shape of the bottom? The tail radius is much smaller than the end attaching to the 2nd bulkhead. Any tips on how to create a very accurate template? I made one out of a thin cardboard, and it's ok, but I feel it could be better.... Thank you, Shawn

How big is the sheet, I have a roll, but it is small. (32")

All do-able but I believe you will also have to form a lip on each side of the panel, plus the bend tapers out on each side. You can make the bends using pipe and your fabricated plywood forms but..... in the end if you ask Cessna to make it for you, it probably be cheaper and fit like a glove. Just my opinion

Jim, if Cessna charges as much as Skywagon City ($921), then I WILL HAVE TO make it myself, no matter what. I got hold of Jim Musgrove today - I'm lucky to have him so close by. He had to rebuild the same piece himself, plus the next bulkhead up. He's been pretty busy lately, but I'll gladly wait to tap his historical knowledge.
The shop where the plane sits has a sheet of .040. We were wondering if that thickness is a suitable replacement for the .032, which seems hard to find. Is that allowable / recommended? I'm guessing not...just keep looking for some .032?

I have found Aircraft Spruce to be a good source for sheet aircraft alumininum.

I use these folks

http://www.airpartsinc.com

they will cut to size.

.032 is very fairly common thickness and I would have thought available from aviation supply stores in the Puget Sound area. I think Shawn you've come a long way, so stay on target and do it the best you can. That in my opinion would be replacing parts with parts fashioned as close to possible as the originals or better. I believe you're going the newer fish mouth tail wheel fitting. I think as multiple structures come together in this area, you should really take your time with aligning and positioning the parts. I believe your going to use the correct size fasteners with your new bulkheads/skin but there are a few stiffeners inside there plus a small intercostal that ties into the aft bulkhead to the sides of that skin. Looking at a B IPC the part I'm referring to are items 13, 14, stiffeners and item 29 in fig 25. Never having done this conversion (new style tail wheel bracket) I don't know if the Cessna kit required the item 29 or if there is one already installed in an A. Model? The bracket is id'd as tail wheel mounting shear bracket thinking you may need some more stuff if their holes have been opened up by the the use of bolts in the old tail wheel bracket.

Thanks Tom and Jim. I recall that website now - love opening it and seeing that couple in a roll of aluminum.
I actually have the tailwheel bracket being repaired. I won't be upgrading to the B-model; not now anyway. I find myself straddling between "repair" and "restoration". Of course I want to do things right, especially while I'm "in so deep", and of course where safety is a concern. But, realistically, I have limited means and have to stay focused every step of the way. If I can get a decent 63 year old plane out of this that I can enjoy for a few years, then I am happy. At the first opportunity I want to park her, tear her down completely and rebuild her...someday. Remember all the lists of "someday-mods" listed in this forum, like Door Stewards, a one-piece windshield, Dodge Atlee folding seats? I have one, too.
The Frankenstein bolts holding the bracket on turned out not to be 1/4". I am considering replacing them with rivets, now that I've become accustomed to bangin' 'em in.
I tracked down a decent priced piece of .032 tonight at Metal Supermarkets in Kent and I'll pick it up tomorrow. Tomorrow after I put my wing back on (Yea! I tried convincing the airport management that with only one wing, my tiedown rent should technically be reduced, as I am only tying down one wing...didn't buy it), I'll start practicing on a thinner piece of scrap to get the shapes right.

Very happy with today....I was able to spend a few amazing hours with Jim Musgrove - see results below....Thank you, Jim!
Next step is to deconstruct the bellcrank assembly, clean it all up, along with the bulkhead and staple it all back together. Sounds easy enough....

spduffee wrote:Very happy with today....I was able to spend a few amazing hours with Jim Musgrove - see results below....Thank you, Jim!
Next step is to deconstruct the bellcrank assembly, clean it all up, along with the bulkhead and staple it all back together. Sounds easy enough....

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NICE !

Wow! You're getting quite the education!

Looks good.