I had worked on the SB during the week as much as I could (which wasn't all that much, but at least I worked on it). So, I had done all the deburring of the side skin doubler and the newly drilled holes. I've also managed to prime the doublers on one side. When I removed the vinyl on one of the large doublers, I've noticed that it some light corrosion which I also removed and sprayed over with primer. That should last until the plane gets painted.
When I sprayed the primer it was already dark and pretty cold too, so I used two halogen lamps to heat up the metal and expedite the curing process. That where the yellowish tint in the following picture is coming from.
Yesterday then was the big work day where I had planned to put all the doublers in place and rivet them on. First I cleaned the U-Section to put the now two skin attach angles in place, using these fancy CherryMax® rivets.
I tapped the wing bolt bushing out a bit more to see how I could get access to the rivet for riveting. I chose the forward-most position as an example as this one appeared to be the trickiest one to get to.
You can see the stripped down riveter in the upper right side of the picture. It appeared that it was a close call but possible to get to the rivet and pull it straight. As a spoiler, and to avoid that you're making the same mistake, let me tell you right here, that it was not good enough. And that includes the aft=most position as well. Do not follow my example and rivet those from below.
The angle was put in place, clecoed and rivets where inserted.
Now, to my own defense, I have to say that I did indeed read the notes about how to install CherryMax® rivets and how important it was that the stem was not tilted while pulling. I can just guess that pulling 20,000 LP4-3 rivets that don't give a damn about the angle of pull, might have given me a callous attitude towards sensing such a tilt.
To me the access to the rivet appeared to be perfectly ok and so I riveted the angles in place
Pulling these rivets feels different than LP4-3, so I didn't know what to make of the sensations I felt in my hand and the unusual sounds I heard. First I thought, it was much easier than I thought it would be and then I looked at the heads. If you look closely, you can see that the stem left a hole in the head on the foremost rivet. The center two do not show that hole. An inspection from below confirmed my fears:
.The stems of the aft and front rivets had not pulled in sufficiently and the stem broke prematurely! I decided to try to drill out the rivets, following Van's note about CherryMax® rivets. While drilling into the stem of the first rivet using a #40 angle drill bit, something felt odd and I pulled the drill out. Oh no!
The drill bit had broken off inside the stem and the piece was stuck in the head. There was no way for me to remove the rivet now, without causing serious damage to this delicate area. I decided against further experiments and instead chose to add two more holes to the angles and the U-section. (I might decide to use a rivet gun on the two stems that have not seated properly to improve the rivet strength but I first have to get one.)
Now being away from the sides of the U-section, the access was definitely easier and the riveter worked as it should.
The rest of this ordeal went much smoother after this CherryMax® rivet episode. The usual CS4-4 and LP4-3 were no problem at all, also the ChreeyMax out the skins were no issue as they were all easily accessible.
That concluded Saturday's work.
Sunday started with the removal of the 1202T angle in the U-section on the right side. This one was much tougher as the ELT bracket is very much in the way of any operation you would like to perform in this area.
The angle drill and thanks to some Yoga lessons helped in getting the job done right.
With the experience from the left side, drilling out those rivets on the right side was a quick job. Note that I clecoed the skin while removing rivets to give it a bit of support.
Match-drilling and deburring went along and soon the skin was ready to receive the doublers.
The doublers were scuffed and primed and dried in the warm sun (76 degF today!).
Right at sunset I finished clecoing the doublers in place for the riveting action to come.
No comments:
Post a Comment