What was found
AIRCRAFT RETURNED TO PLATFORM AS A CONSEQUENCE OF OIL STRAINER CLOGGING LIGHT TURNED ON. PRESSURE SWITCH AND STRAINER CLOGGING OIL SWITCH WERE CHECKED AND LEAK TEST WAS PERFORMED, ALL CORRECT. THE LEFT FILTER WAS REMOVED, CLEANED AND INSTALLED, TEST WAS CORRECT IAW MM 79-20-06. DURING OVERNIGHT SERVICE THE FILTER WAS REPLACED IAW MM 79-20-06, TEST CORRECT.