04 March 2015

Fuselage: Forward mid fuselage lower structure. Muffler shrouds on.

For the side shrouds, I did two things contrary to plans:
  1. I did not rivet the F-01453-L/R muffler shroud doublers and F-01465 muffler hanger angles to the shroud sides until after the shroud sides were themselves riveted to the bottom skins.  I saw that the muffler doublers and angles would impede rivet access on the flanges of the shroud sides.  I tested to ensure I could access the doubler and hanger rivets with my squeezer once the sides were riveted down.
  2. I decided to seal and rivet the F-01454 muffler shroud ramp following riveting of the shroud sides because I thought it would be easier to manage riveting the shroud sides without the ramp in the way and wobbling around a lot.
So....after I sealed the F-01453-L/R muffler shroud sides to the F-01483-L/R forward bottom skins, I set the assemblies aside for a few days to let the sealant cure a bit to reduce mess, as shown in the left image.  The right image shows the riveted assemblies. 

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I back riveted all of the rivets save the aft 5 rivets on each side.  For those boys, I had to get creative, as I work mostly alone.  A combination of holding the skin with my legs and trapping the assembly between my EAA Chapter 1000 workbenches, let me finish off those aft rivets.



Here is the inboard side of the muffler doubler (left) and muffler hanger (right) for the left assembly.  The excess sealant at bottom of the image is easily cut away later.


Next, the muffler shroud ramp needs to be sealed in.  First, I decided to wipe a thin layer of sealant on the flanges of the shroud sides and ramp to make sure I wasn't completely reliant on an exterior, exposed fillet of sealant as suggest in the plans.

Then I cleco'd the ramp to the right shroud side first.


Then using the space between my EAA Chapter 1000 workbenches, I inverted the forward bottom skins so the shroud could fit between them and cleco'd in the left side shroud.  Access isn't as easy, but my back is good for it.


Next a sealant fillet is applied and smoothed with a Popsicle stick.  Close up of the fillet (left) and looking down (well, up really) the ramp (right).


And here the assembly sat for a few days to let the sealant cure a bit before final riveting.  Thankfully, the riveting of the ramp to the shroud sides can be done with a squeezer.  The boards were to keep the skins straight and weighted down so the latter could keep their shape during sealant curing.


For the aft-most 2 rivets that fasten the shroud sides to the ramp, I could not get a squeezer yoke to fit in there nor could I get a bucking bar in there.  However, I had a long, thin steel bar I obtained for one of the harder-to-reach rivets on the rudder (it didn't work very well for that purpose).  I used that rod with another bucking bar as a fulcrum to help keep pressure against the shop head.  A couple of Popsicle sticks on one side of the bar helped angle the bar to match that of the rivet to prevent the latter from clenching over.  Worked great.


Completed assembly awaiting mating to the firewall.


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