What was found
MAIN CABIN UNDER FLOOR PANEL#221BF CORROSION POWDER IS ON TOP OF THE INTERCOSTAL AND AVIONICS TRAY. INTERCOSTAL IS LOCATED BETWEEN STA 294.5 AND 312 LBL 13' / INSTERCOSTAL AT STA 294.5 TO STA 312 LBL 13 CORRODED; REMOVED CORROSION AND VERIFIED ORIG 'T' .170' MATERIAL LOSS .040'; REMAINING 'T' ;130' FOUND TO BE OUT OF LIMITS IAW SRM 53-10-51-1A-1 FIG 105 DETAIL C TOOL USED AAR 36649 DUE 7/5/2018. REMOVED INTERCOSTAL AND INSTALLED NEW INTERCOSTAL IAW BOEING DWG 141A5600 REV N AND SRM 51-40-02-0G-0.