As reported to the FAA. Reports are unverified, and codes are left as the FAA publishes them.
What was found
MANY CYLINDER HOLD DOWN NUTS WERE LOOSE ON INSPECTION OF TORQUE OF THOSE NUTS. THIS HAS BEEN OCCURING ANNUALLY. MFG IS USING A NYLON TYPE SELF LOCKING NUTS TO HOLD DOWN THE CYLINDERS. MOST ENGINE MFG DO NOT USE NYLON NUTS ON THE ENGINE AT ALL LET ALONE THE CYLINDER HOLD DOWN NUTS. SUBSTITUTION WITH A STEEL SELF LOCKING NUT OR A STEEL NUT WITH THE A PAL NUT MIGHT BE AN APPROPRIATE ACTION.