Matt's RV-8 Project



Matt Dralle's RV-8 Project
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Date:  7-5-2009
Number of Hours:  0.50
Manual Reference:  
Brief Description:  Drilling Rear Spar Bolt Hole - Part 1

Drilling the rear spars for the attachment bolts is a bit nerve racking because you only get exactly one chance to get it right. You have to adjust the wings such that the fore/aft position of the wings is correct all the while making sure that the incidence (angle of attack of the wing) is also correct. Alignment involves cutting a 2 51/64" piece of wood and placing a long level on the wing just right, comparing the measurement to another level sitting on the top longeron which was previous set to zero by exactly raising and lower the tail of the airplane. When drilling the hole, you have to make sure that there is exactly 5/8" of clearance all the way around the bolt hole. I accomplished this by making a paper template and taping it to the spar right where I wanted the hole. The template allows for finding the exact center of the spar and as a drill guide. It worked out amazingly well. I started drilling at 1/8", checked all of the alignments again, then to 3/16" checking the alignments again, then to the final 5/16" size. The bolt uses a castle nut and cotter key which seems really strange to me. It would seem that you would want this to be a tight fit, but I guess not. Anyway, for some reason I didn't get the AN5-10 (predrilled for cotter key) bolts and temporary used some AN5-10A bolts. Over all, the installation came out great and I'm glad this rather stressful job is complete.
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Left Wing - Measuring The Incidence

Left Wing - Measuring The Incidence

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Left Wing - Measuring The Incidence

Left Wing - Measuring The Incidence

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Left Wing - 5/8

Left Wing - 5/8" Hole Template

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