I decided with my Tech Counselor that it would be a good idea to take the VS and Rudder down to him for him to have a look inside, before i riveted on the trailing edges and closed the structure up forever! Overall, Pete was pretty happy with my work, but identified the following items:
1. 3 rivets on the lower section of the VS spar: In this case, after completing the back riveting of the lower AN426 flush rivets on the VS spar, i moved onto the AN470-AD4 rivets. I used a squeezer for these, however inadvertently picked up a AD3 sized cupped set instead of an AD4 size. I set 3 rivets before i realised. These left a concentric mark on the rivet head, which Pete said could cause a cracked rivet later. So out they came!
A note on removing AD4 size rivets: i have found these pretty hard to remove initially, especially where there was a lot of material. I worked out the best process was to use a #31 (or 1/8") drill bit to drill off the head. This leaves a conical indentation from the end of the drill bit, so i then use a #31 (or 3/32") drill bit to drill down into the shank, keeping it carefully in the indentation, and being careful not to touch the skin. This gives some room for the rivet tail to collapse and it tends to punch out a lot easier. If it doesn't punch out, i use a pair of ground down side cutters to twist the tail of the rivet off (as per Van's Section 5).
2. Some of the smaller AD3 rivets on the stiffners of the rudder or the VS parts were slightly over driven. It seems i tend to go slightly over, then slightly under. Pete recommended going slightly under is better than over.
3. When i scuffed the rudder hinge brackets on the VS, i inadvertently scuffed off the powder coat on the edges. Pete thought it best that i re-painted these for corrosion protection. For this i just sprayed some rattle can etch primer that i had into a cup, and brushed it onto the edges and the bolt holes.
4. Finally, Pete noticed a couple of fish eyes in the primer on the VS stab and asked about my shop air setup and priming practices. I told him that i had a dedicated painting line etc etc, and i mentioned how i was drying the parts by blowing them off with shop air... doh! headslap! Pete pointed out that i was using the same hose to do this blowing off that i was using for my air tools, which had oil in them! So i need to stop doing that!
Overall the first TC visit went very well, and i took away some good advice. Here is the first TC report:
1. 3 rivets on the lower section of the VS spar: In this case, after completing the back riveting of the lower AN426 flush rivets on the VS spar, i moved onto the AN470-AD4 rivets. I used a squeezer for these, however inadvertently picked up a AD3 sized cupped set instead of an AD4 size. I set 3 rivets before i realised. These left a concentric mark on the rivet head, which Pete said could cause a cracked rivet later. So out they came!
A note on removing AD4 size rivets: i have found these pretty hard to remove initially, especially where there was a lot of material. I worked out the best process was to use a #31 (or 1/8") drill bit to drill off the head. This leaves a conical indentation from the end of the drill bit, so i then use a #31 (or 3/32") drill bit to drill down into the shank, keeping it carefully in the indentation, and being careful not to touch the skin. This gives some room for the rivet tail to collapse and it tends to punch out a lot easier. If it doesn't punch out, i use a pair of ground down side cutters to twist the tail of the rivet off (as per Van's Section 5).
2. Some of the smaller AD3 rivets on the stiffners of the rudder or the VS parts were slightly over driven. It seems i tend to go slightly over, then slightly under. Pete recommended going slightly under is better than over.
3. When i scuffed the rudder hinge brackets on the VS, i inadvertently scuffed off the powder coat on the edges. Pete thought it best that i re-painted these for corrosion protection. For this i just sprayed some rattle can etch primer that i had into a cup, and brushed it onto the edges and the bolt holes.
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| Here you can see how i scuffed off the powder coating |
Overall the first TC visit went very well, and i took away some good advice. Here is the first TC report:
So after rectifying all those issues, i was able to successfully rivet the rear spar into the VS and finally the VS is complete.
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