170C wrote:First I am thinking of replacing the six (6) screws that hold the fuel tank adapter (AN 520-10R10) with stainless screws if they are available because they sit in the bottom of the moat (adapter) and are subject to standing water if the plane is out in the rain. Any reason not to do so? Are stainless screws of this part number available?
According to Genuine Aircraft Hardware Co.
http://www.gen-aircraft-hardware.com AN 520-10R10 has been superseded by MS35207-264, a low carbon steel cad plated pan head screw. You could also use a structural pan head screw with corrosion resistant steel MS27039C-1-10 or if you wanted stainless (non-structural), MS51958-64. My preference would be option #2. Stick with pan head screws as the flat area in the moat is only .330" wide. A washer head screw will end up riding on the radius of the moat. Also don't forget the o-ring "washers" under the screw heads. See
http://www.cessna170.org/forums/viewtop ... 405#p56405 for related ideas.
170C wrote:Next, what are the various sources for the fuel filler gaskets (3 each side)?
It might be cheapest to have them "owner produced" at a local shop. Otherwise google the part number and look for the best deal. A quick search found 0523532 for $13.25 and 0523531 for $15.60 at
http://www.airward.com
170C wrote:The neopreme "pads" (0523521-5 & 0523521-6) that must be those that are under the hold down straps and on the ribs under the tank, plus possibly the small pad on the "block" can likely be fabricated from sheet neopreme purchased at vrs local suppliers, but I don't know the thickness of the material. Jim W. mentioned that he used some which was a bit thicker than original and it make reinstallation of the tanks a BEAR! I would like to avoid that if possible. Anyone know what the correct thickness should be? I noted that Spruce has anti-chafe molding available that accomodates staps up to 1 inch in width (their part # 05-01800) but without the proper thickness data I don't know if that would work or not.
The hold down straps are 1/2" wide .040" aluminum. Each strap is roughly 44" long. My strap had 3/4" wide, 1/16" thick rubber glued on with contact cement. Probably not original. You could go with this from Brown Aircraft Supply:
- CH-609-8
- fuel anti-chaff strap.jpg (11.61 KiB) Viewed 52739 times
There are seven hat sections all together in each wing fuel bay. 6 are 33" long and the one that is near the filler opening is 25" long. The top of the "hat" is 5/8" wide. Order at least 223" of anti-chafe material to cover each hat section in ONE wing. You might consider Aircraft Spruce's p/n 05-00664 silicone anti-chafe seal kit or order directly from Gee-Bee Aero Products 800-556-3160 /
n77gb@msn.com
170C wrote:Finally, my 56 C-170B parts catalogue and my C-172 parts catalog's specify the number of vrs length/size screws needed for the wing panel that has to be removed over each tank, but it doesn't specify which length screws go where (seems there are 4 sizes--NAS 228-12; -9; -8 & -7's). Nothing in there about where the different sizes go in the panel. I seem to remember when I removed one of the panels years ago that the ones across the leading edge of the panel were longer than the others, but I might have that reversed. I don't recall there being 4 different lengths, but that was a long time ago and I likely didn't recognize but 2 different lengths at the time. Sort of thinking about getting all of the screws in stainless if available.
My parts book shows 14 NAS228-12 screws and 37 NAS 228-8 screws on fig.7-45 and 7-46. The 14 longer ones go along the leading edge (through the front spar). Do not use stainless screws here as stainless is non-structural. As the NAS part numbers are obsolete use 37 MS27039C0808 and 14 MS27039C0812 corrosion resistant screws. Dip the screws in zinc chromate before installing them--it'll help the next guy get them out.
) have some questions. First I am thinking of replacing the six (6) screws that hold the fuel tank adapter (AN 520-10R10) with stainless screws if they are available because they sit in the bottom of the moat (adapter) and are subject to standing water if the plane is out in the rain. Any reason not to do so? Are stainless screws of this part number available? Next, what are the various sources for the fuel filler gaskets (3 each side)? The neopreme "pads" (0523521-5 & 0523521-6) that must be those that are under the hold down straps and on the ribs under the tank, plus possibly the small pad on the "block" can likely be fabricated from sheet neopreme purchased at vrs local suppliers, but I don't know the thickness of the material. Jim W. mentioned that he used some which was a bit thicker than original and it make reinstallation of the tanks a BEAR! I would like to avoid that if possible. Anyone know what the correct thickness should be? I noted that Spruce has anti-chafe molding available that accomodates staps up to 1 inch in width (their part # 05-01800) but without the proper thickness data I don't know if that would work or not. Finally, my 56 C-170B parts catalogue and my C-172 parts catalog's specify the number of vrs length/size screws needed for the wing panel that has to be removed over each tank, but it doesn't specify which length screws go where (seems there are 4 sizes--NAS 228-12; -9; -8 & -7's). Nothing in there about where the different sizes go in the panel. I seem to remember when I removed one of the panels years ago that the ones across the leading edge of the panel were longer than the others, but I might have that reversed. I don't recall there being 4 different lengths, but that was a long time ago and I likely didn't recognize but 2 different lengths at the time. Sort of thinking about getting all of the screws in stainless if available. Suggestions appreciated.
