What was found
WHEN AIRCRAFT TOUCHED DOWN DURING HOVER LANDING A VIBRATION (IMBALANCE) WAS FELT IN THE ROTOR SYSTEM. PILOT SHUT DOWN AIRCRAFT AND IT WAS TOWED TO MAINTENANCE BASE. MECHANICS FOUND THE B NUT ON THE DAMPER HYDRAULIC ACCUMULATOR QUICK DISCONNECT LOOSE WITH A LOSS OF HYDRAULIC FLUID. THERE HAD NOT BEEN ANY MAINTENANCE PERFORMED IN THIS AREA RECENTLY. THE QUICK DISCONNECT IS AND WAS SAFETED BUT THE B NUT THAT THREADS ONTO IT HAS NO SAFETY CAPABILITY.