John I think your right about the lock washers not performing. I noticed that the engine mounting bracket arm was flexing slightly when I was aligning the bolts. Although they firmed up when I tightened the bolts to the engine it would seem that they shouldn't rely solely on the engine case for rigidity. This is a high speed, high compression engine. It seems to me that a significant amount of energy retention would be concentrating where the brackets clamp to the engine. I'm probably over-analyzing. Hopefully Vans engineers will get back to us soon. In the meantime I will continue to inspect the bolts and enjoy the plane.