As reported to the FAA. Reports are unverified, and codes are left as the FAA publishes them.
What was found
AFT WET AREA SILL WEB HAS MULTIPLE AREAS OF CORROSION BETWEEN STA 986 TO STA 1006 RBL-28 TO RBL-42. GROUNDED - YES. REMVOED CORROSION FOUND TO BE OUT OF LIMITS IAW B737-900 SRM 53-70-51-1A-1 REMVOED AND REPLACED SILL WEB IAW B737-900 SRM 51-40-02-0G-0W= 1.0 O= .084 R= .074 L= 2.0 D= .010.