Four reported incidents of in-flight loss of hydraulic fluid led to an emergency AD for 139 Premier Is. None of the incidents led to any mishaps. The problem has been traced to the failure of a hydraulic tube assembly in the left engine. The January 20 directive requires a visual inspection of the affected part before further flight and subsequent inspections at intervals of 50 hours. A Raytheon Aircraft spokesman told AIN, “Our teams in the field have been contacting customers, and replacement tubing and clamps have already been manufactured; many are already in the field.” Additionally, he said the company is working on design changes. “Once implemented, the 50-hour inspection will be removed.”