What was found
DURING ROUTINE 500 HOUR INSPECTION IT WAS DISCOVERED THAT THE CASTING AT THE AFT MOST POSITION OF THE TAILBOOM, WHICH IS THE ATTACHMENT POINT FOR THE FENESTRON (DUCTED FAN TAIL ROTOR) HAD SEVERAL CRACKS EXCEEDING 1.5 INCHES RADIATING FROM ONE POINT AT THE 3:00 POSITION WITH TAILBOOM VIEWED FROM THE REAR. THIS CRACKING COULD ONLY BE VIEWED EASILY WITH THE HORIZONTAL STABILIZER REMOVED. THIS WAS DETERMINED BY THE OEM TO BE A NON FIELD REPAIRABLE DEFECT AND SERVICEABLE TAILBOOM ASSEMBLY HAS BEEN ORDERED AND WE WILL REPLACE THE DEFECTIVE TAILBOOM WHEN IT ARRIVES IAW THE MANUFACTURERS INSTRUCTIONS AND TECHNICAL REPRESENTATIVE’S SUPERVISION. IT DID NOT APPEAR THAT A CATASTROPHIC FAILURE WAS IMMINENT. (K)