What was found
WHILE EN ROUTE, HYDRAULIC PRESSURE WAS NOTED TO FLUCTUATE THEN REMAIN ON ZERO. AN ALTERNATE AIRPORT WITH A LONGER RUNWAY WAS CHOSEN. WHILE APPROACHING AIRPORT, HYDRAULIC PRESSURE RETURNED TO NORMAL AND AN UNEVENTFUL LANDING WAS MADE. HYDRAULIC PRESSURE REGULATOR WAS REPLACED AND SYSTEM TESTED NORMAL. RECOMMEND REPLACING HYDRAULIC REGULATORS WHEN ERRATIC OPERATION IS ENCOUNTERED.