What was found
WHILE PERFORMING A LIFENET AAIP INSPECTION, THE MECHANIC FOUND A .7500 INCH (APPROX) CRACK EXTENDING FROM THE UPPER LEFT HAND T/R GEARBOX MOUNT HOLE INBOARD THROUGH AN ADJACENT RIVET HOLE TERMINATING AT A CORNER FILLET, ON THE MOUNT FITTING FOR THE TAIL ROTOR GEARBOX. THE AIRCRAFT WAS REMOVED FROM SERVICE AND TRUCKED BACK TO SAINT LOUIS, MO. FROM JOPLIN, MO. FOR TAILBOOM REPLACEMENT. THE AFFECTED TAILBOOM WILL BE SENT TO EUROCOPTER CANADA FOR MOUNT FITTING REPLACEMENT. THE CRACK WAS FOUND VISUALLY AND VERIFIED WITH DYE PENETRANT. THIS AREA OF THE TAILBOOM HAS BEEN KNOWN TO CRACK, IT IS IMPERATIVE THAT THOROUGH INSPECTIONS ARE PREFORMED AT SCHEDULED INSPECTION INTERVALS.