What was found
RT HORZ LOWER SKIN HAS A CRACK AT STA 138 (MARKED) A154-002. GROUNDED - YES. REPAIRED DAMAGE TO LOWER SKIN, IAW B737-800 SRM 55-10-01-2R-11 REP 11. THIS IS A CATEGORY B REPAIR, WITH AN INSPECTION THRESHOLD OF 56,000 TOTAL FLIGHT CYCLES AND AN INTERVAL OF 9,000 FLIGHT CYCLES THEREAFTER.