To clean out the holes through the wing fittings and spars I attached the flexible drill shaft to get in awkward spots that the drill can't fit.
I have decided to substitute AN 365 elastic stop nuts for MS 21042 all metal stop nuts and where appropriate AN960 steel washers will be replaced with AN960PDL aluminium ones. At 3-1/2 times lighter, all the grams are going to add up. 4 grams saved per bolt means I can save an ounce for every 8 nuts swapped over.