The HS-906 spar doubler plate comes preformed, but it is pretty rough on the edges and is also quite bowed. I worked on the edges with a file, then smoothed everything on the scotchbrite wheel. Cleco'ed it together with the HS-903 rear spars, match drilled all of the holes. Marked 2 holes on this side for countersinking. They need to be flush for when the tail is attached to the fuselage (had to check on drawing 27A in the preview plans).
