I'm ready to install the Ballast Weight Weldment on my A600 kit.  Seems pretty straightforward, however I'd like some perspective and suggestions on a concern I have.    The weldment fits well longitudinally, doesn't look like I will need any shims where it bolts to the Tailboom bulkheads.   However, the attachment plate sits over 3/16 inches above the tail boom skin.   That's a stack of several pieces of aluminum for a pretty dang thick shim.    Looking at why it sits so high,  I see, and these pictures show, the weldment bracket at the forward bulkhead is interfered with by rivets.    The unusual thing, is of all the rivets on that bulkhead, only these two protrude that high (mandrel head).   These two rivets are at the point where the small panel on the bottom of the tail boom overlaps the primary skin and the stringer, so there are four layers being held by those two rivets.   The panel skin the primary skin, the stringer, and the bulkhead.   

I'm not a sheetmetal expert, not professionally trained on sheetmetal work.   Cherrylock,  CherryMax, all exceed my level of training.  I'm pretty good with traditional aluminum solid shank rivets and Rotorway level pop rivets.   I'm looking for thoughts.
Seems like I can mount it as it sits, and stack about 7/32" of aluminum shims between the mounting plate and the tailboom skin, possibly remove some material from the weldment bracket to give clearance/space for the rivet mandrel, or ?

Hopefully these pictures will illustrate the question.   The tube portion of the weldment is resting on the rivet mandrel.


  
 

Hi Sam, i would personally re-pull a cherry max in that location, doesnt look like the mandrel seated all the way in the rivet, is it broke flush on the head or recessed a bit? if you need help removing it you can message me for guidance.

not sure the weldment needs to be against the skin, its just a structural member joining the 1 and 2 bulkheads, i'll check mine tonight to see if the skin joins with it and my clearances.

(02-02-2026, 09:30 PM)Lyle Swallows Wrote: Hi Sam, i would personally re-pull a cherry max in that location, doesnt look like the mandrel seated all the way in the rivet, is it broke flush on the head or recessed a bit? if you need help removing it you can message me for guidance.

not sure the weldment needs to be against the skin, its just a structural member joining the 1 and 2 bulkheads, i'll check mine tonight to see if the skin joins with it and my clearances.

 Here is the rivet in question on the outside.  The mandrel is definitely recessed in the rivet head.    Both sides are identical.   I'm going to plan on just replacing those two rivets.   I can add Cherry Max to my rivet hardware box..   The instructions say there may be a gap and if so, to make a shim.   I have looked into the tailboom of another talon awhile back and they had a shim.   But it was small.   Maybe  .020-    nothing like this large gap.   I suspect a new rivet properly installed would reduce my gap considerably.