What was found
ETOPS PREDEPARTURE SERVICE CHECK (PDSC) PROCEDURE. AFT WASTE SYS VACUUM BLOWER VENT PORT HAS AREA OF BUBBLING PAINT WITH UNDERLYING CORROSION. FOUND TO BE OUT OF LIMITS IAW SRM 53-00-01-1A-1, DETAILS A FOR EDGE DAMAGE EXCEEDING THE ALLOWABLE .190" AND DETAIL D VIEW A-A FOR DEPTH OF DAMAGE BEING BEYOND .15T. WILL REQUIRE REPAIR. EVALUATED EXHAUST PORTS AND FOUND EXFOLIATION CORROSION ON THE FWD PORT, REMOVED CORROSION ON AFT PORT, REMOVING APPROX .044" MATERIAL THICKNESS. APPLIED EWIS PROTECTION ON INTERIOR SURFACE AT LOCATION OF AFT LAV VENT IAW AMM 20-60-07. CLEANED INTERNAL AREA OF AFT LAV VENT & FOUND NO VISIBLE SIGNS OF CORROSION. REMOVED EVIDENCE OF CORROSSION ON EXTERNAL SKIN AT AFT LAV VENT. PERFORMED ULTRASONIC THICKNESS CHK OF BLENDED AREA OF AFT LAV WASTE VENT, LOWEST REMAINING THICKNESS 0.086" IAW NDT PT 4. 51-00-10, PROC 2, REWORKED AREA IS GREATER THAN 15% OF ORIGINAL THICKNESS AND OUT OF LIMITS IAW SRM 53-00-01-1A-1. PERFORMED STEPS A,B,C,D & F OF SRM 53-70-01-2R-1, PARA 4. PERFORMED HFEC OF CUT EDGE OF CUT OUT. ACP STEP E PERFORMED HFEC OF CUT EDGE VERIFIED NO CRACKS INDICATED.REF NTM PT 6 51-00-00. NEED TO VERIFY REPAIR.