What was found
THIS EO IS BEING ISSUED TO PROVIDE INSTRUCTIONS TO ACCOMPLISH THE PERMANENT REPAIR OF CORROSION DAMAGE TO THE AFT CABIN FLOOR STRUCTURE RT AFT SEAT TRACK PN 170-86082-003 AT FRAME 84. THE APPROX DAMAGE DIMENSIONS ARE AS FOLLOWS 4.0 INCHES X 1.2 INCHES WITH .039 INCH MATERIAL REMAINING. BECAUSE THE FLOOR TRACK IS A PSE. ACCOMPLISHMENT OF THIS EO HAS BEEN CLASSIFIED AS A MAJOR REPAIR DUE TO STRENGTH RESTORATION. THIS IS NOT CLASSIFIED AS FCS, BUT REQUIRES FOLLOW UP INSPECTIONS THAT WILL BE ACCOMPLISHED ON EO E175-53MR-172.1 IAW ANAC DER FORM ATTACHED. TASK 53-23-005-0001 INTERNAL GVI, THRESHOLD OF 20,483 FC, INTERVAL OF 10,133 FC OR THRESHOLD OF 27,242 FH, INTERVAL OF 13,476 FH, WHICHEVER OCCURS FIRST, IS SUFFICIENT & IS MET USING THE INSPECTION REQUIREMENTS MPG & MRBR REVISION 10. THRESHOLD IS COUNTED SINCE NEW. THRESHOLD TASK 53-23-005-001 WAS ACCOMPLISHED DURING THIS CURRENT B4 BASIC CHECK. SUPPLEMENTAL FOLLOW UP INSPECTIONS WILL BE SET & FOLLOW THE INTERVAL OF 10,133 FC OR 13,476 FH IAW ETD2015-170-029174 ANAC DER FORM ATTACHED. ACCOMPLISHMENT OF THIS MAJOR REPAIR WAS ON EO E175-53MR-172 UNDER WO 1894785.