part question

[flag8r77]

Just replacing my main gear and I realized that I've been missing the flat washers that go onto the M3x8 cap screws that go into the main gear to secure the oneway hub...

What's the purpose of these flat washers (M3X8X1mm) and are they necessary? I've flown about 20 flights without them :wow2:

[Foxden]

Gives the screw head a bit more surface to spread out the load I would assume so it doesn't pull the head into the gear.