Ibid...

If it's coming loose, you're wood is compressing, or your not tightening the nut enough.

Every time I see this happening to someone, I pull out a larger wrench than what they have on hand and REALLY tighten it down.

The standard response I get is "aren't you afraid of stripping the nut?" but their prop nut no longer falls off.

The double lock nut is a good safeguard, particularly for wood props, but it shouldn't be needed for composite props.

Locktite? No thanks! I already have problems getting locknut off.