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21iS/U-03 Figure 2

Rob H

Well Known Member
I?m needing clarification. I?m working on the iS fuselage kit. On page 21iS/U-03, Figure 2, at the bottom left side of the diagram, it says ?CS4-4, Both Ends Flush FWD Side?. I?m not sure what this means. Does this only apply to the single hole that the arrow appears to be pointing to? And does the flush manufactured head go on the F-01204D-1 side just like the LP4-3 rivets do? I don?t understand where the CS4-4 rivet or rivets must go and why it can?t be a LP4-3. Thanks
 
A CS4-4 rivet is a Counter Sunk / flush rivet.

Because of that, the hole it goes in must be prepared in some way for a flush rivet (dimple countersunk or machine countersunk).

The hole pointed to by the arrow was specified to be machine countersunk in Section 20iS/U, page 3, Step 8, for a CS4-4 countersunk rivet.

The riveting statement means to say the countersunk hole at each end of the bulkhead (it assumes since you are installing a flush rivet, you will be looking for holes that are either dimple countersunk or machine countersunk. At this point in the assemble process there are only two. The upper hole for attachment of the two F-01223 ribs.
 
Okay, that makes sense. I will look for the countersunk rivet hole when I get home. Thanks!
 
My builder friend ran into this issue, messed it up… wondering why it needs to be flushed fwd side. He’s calling in soon to ask about fixes, but we’re not seeing why that rivet needs to be flush fwd side… trying to learn what happens and not seeing it in the plans as self-explanatory….

Patrick
 
It’s been a few years but I think if you look at 35iS/U03. There some mounting plates where the gear bolts. My bet is a regular LP3 would foul that plate, hence a CS,

Robert
 
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