Rudder Trailing Edge Riveting

Sunday 20th April (4hr 45min)

Riveted rudder and left & right elevator trailing edges. Pop-riveted trim tab end tabs and trim tab horn. Match-drilled hinge to trim tab upper skin & spar and cut to length.

It is a week now since 'tank sealant day' so I went back to work and began by removing the clecos and cleaning the little stray bits of solidified tank sealant out of the dimples and holes. The edges are still laser-straight at this stage but it is the riveted end-product that counts. I did notice one place where the tank sealant was lifting the skin off the trailing edge wedge very slightly. Obviously, this was close to the end of the sealing job when the sealant was getting very stiff and lumpy and difficult to spread.

The idea here is to half set each rivet with a back-riveting set, flip it over and then finish by riveting on the manufactured head with a mushroom set. In the event, I was not very comfortable with the back-rivet set and decided to try the air squeezer with the gap set to squeeze each rivet just enough to fix it in place. I found this easier although I had to be careful to exert enough pressure on the manufactured head with the non-moving side of the squeezer to ensure it was fully seated in its dimple before it was fixed in place. I worked on every fifth rivet from the centre out and then went back to do the rest randomly.

I was very pleased with the results. I would call it perfect if it were not for that little bump caused by tank sealant and I think the edge material is microscopically dented by the action of the rivet set at each rivet site. It certainly no longer looks like pristine new aluminium sheet but I think paint will hide that completely.

Another anxiety-causing job off the list!

With time on my hands, I went on to pop rivet the control horn to the trim tab. If I had not forgotten this step before 'tank sealant day', I could have easily done these with solid rivets using the longeron yoke. In fact, I should also have solid riveted the bottom skin-spar join at that stage so that will also have to be pop-riveted. The manual quotes MK-319-BS pop rivets as an alternative here. However, I don't have enough of these rivets to cover all locations where they are called out or are an option. I will have to get 30 more from Vans.

I also put pop rivets into the ends of the trim tabs and match-drilled the hinge to the underside of the top flange of the spar. I got this dead wrong first time but fortunately caught my mistake before I had cut the hinge so I was able to re-position the hinge and match-drill again. The first set of holes won't do any harm and can be regarded as 'lightening' holes - if they are ever noticed in such a well-hidden location.