What was found
DURING HEAVY MAINTENANCE, CORROSION WAS DISCOVERED ON AFT CABIN STRINGER 21L BETWEEN FRAMES 88 - 89. CUTOUT THE STRINGER. PERFORMED HFEC IAW NDT PART 1, 51-00-00-916-803. INSTALLED NEW STRINGER BETWEEN FRAMES 88 - 91. FABRICATED REPAIR PARTS AND INSTALLED NEW STRINGER 21L. C/W IAW E14-466-01 AND SRM 53-23-03, FIG 25, ITEM 100A. RETURN TO NORMAL CONFIGURATION.