What was found
EXTERIOR FUSELAGE SKIN BS.500E TO 500K STR.0 HAS SIGNS OF CORROSION AROUND BELLY DRAINS (5EA.CIRCLED). GROUNDED - YES. REMOVED CORROSION FROM 5 EACH LOCATIONS IAW B737-900 ER SRM 51-10-02. ORIG THICKNESS .063 IAW B737-900 ER SRM 53-30-01, LOWEST READINGS AT STA'S, 500E, 500H, 500I, 500O, REMOVED .003 REMAINING MAT .060 FOUND TO BE IN LIMITS IAW B737-900 ER SRM 53-00-01, REINSTALLED DRAIN PLUGS IAW B737-900 ER AMM 51-41-13, TOOL #T8927K CAL DUE 27/SEP/24. THIS IS A CAT B REPAIR REINSPECT REQUIRED 50,000 FLIGHT CYCLES FROM AIRPLANE DELIVERY PER B737-900ER SRM 53-30-01-1A-1 TABLE 103, SUBMITTED TO ENGINEERING FOR TRAX THIS CLOSES THE DEFECT.