What was found
SIDE SEAT RAILS FROM FS 720 TO FS 977 ( 4 SEAT RAIL SECTIONS) ARE CORRODED BEYOND LIMITS. CORRECTIVE ACTION: REMOVED AND REPLACED 4 SIDE SEAT RAILS (PNS: SH690-37542-1, SH690-36285-1, SH670-36260-953, SH670-37543-3) IAW CRJ900 SRM 51-21-06, C53-41-49, 53-51-49, CRJ 900 AMM 53-00-49.