As reported to the FAA. Reports are unverified, and codes are left as the FAA publishes them.
What was found
WHILE TROUBLESHOOTING MAST MOMENT INDICATION PROBLEM, HAD TO REMOVE MAIN ROTOR SHAFT ASSEMBLY, WHILE REMOVING SHAFT FOUND MAST NUT LOOSE. REMOVED NUT BY HAND. ALL LOCKING HARDWARE WAS FOUND TO BE INTACT AND SECURED AS REQUIRED. UPON FURTHER INSPECTION, FOUND MAST PROPERLY SEATED IAW EC135 MM 62-31-00-4-3 DIMENSION X WAS .590. ATTACHED HOIST TO MAST AND NO TENSION WAS NEEDED TO REMOVE MAST. AWAITING INSTRUCTIONS FROM MFG.