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Bill & Brendas RV-8 QB
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Date:  8-24-2014
Number of Hours:  2.00
Manual Reference:  
Brief Description:  propeller bolt washer modification to fit

I asked a friend and builder at the airport Mike for his input on what should be done about the washers called out for use under the prop bolt heads. They are way way to large in diameter to sit flush on the crush plate. The smaller washers supplied ater for 7/16 bolts and looked like they would fit but the hole needs enlarged to 1/2" too. So, Based on Mikes input, I elected to use the smaller diameter washers and inlarged the bolt holes in all 6 to 1/2 inch on the drill press. Another neat idea from Mike was to mark the crease line in the crush plate with sharpie, install the bolt and washer and turnand press the washer to leave a rubbed out mark in the marker. This shows when the washer contact edge is inside the crease. Turns out that even the smaller washers need some material removed from the edge as well. The idea was to do a nice rounded bevel to clear the crease. I cut a half inch bolt head off and nut in the washer and installed in drill press to spin it while holding a file at an angle to make a bevel. Then when the bevel made, finsished off with a rotation of file to round out. Then worked out nicks and burrs on the scotch brite wheel. Time consuming process because Id check fit with the sharpie method each time before moving on to another washer. When done, I cleaned them up and primered before installing.

NOTE: checke vans airforce about this problem and its not isoltated. I see some folks complaining about this and all with the o360 engine with fix pitch and vans supplied washers not laying flat. Vand told one guy 5 years before to remove material from edge until they lay flat. Long story short. Builders have either removed material around the big washers until fit or cut out a flat just where the washer contacts crease, or done what Ive done and enlarged hole in smaller diameter washer so that less material needs removed from outer edge. The bevel idea from Mike helps retain more washe material and is a good clean method I think.
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Prop bolt washer locked in drill press and using a file to bevel the edge for nice fit

Prop bolt washer locked in drill press and using a file to bevel the edge for nice fit

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Sharpie used to mark crease and washer turned in the area  until inside the crease mark

Sharpie used to mark crease and washer turned in the area until inside the crease mark

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All 6 washers drilled and filed to fit

All 6 washers drilled and filed to fit

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