What was found
DURING 4,000 HOUR CHECK, CHAFING WAS FOUND ON LT I/B NACELLE SKIN. MAINTENANCE COMPLETED EO NR S54009, BLEND OUT THE CHAFING AREA SMOOTHLY, REINFORCED WITH DOUBLER, SEALED DOUBLER WITH NEW FASTENERS INSTALLED PER NAS1669-3 IAW SRM 51-20-42/43.