Just Curious here...The drawing shows the locking surfaces against each other, and the surfaces against the bolt head and the bolted surface as smooth. Do these bite into the other surfaces as well?? In my experance a smooth washer like this can still work loose..if it was a lockplate that is physically bent over the bolted surface and bent up against the flat of the bolthead is the only preferred method to locking fastners aside from wire(MIL STD 763)
Jeff