What was found
LOWER FUSELUGE SKIN JUST FWD OF STA 400, FWD SIDE OF DRAIN PLUG SKIN HAS CORROSION MARKED. GROUNDED - YES. REMOVED DAMAGE AND CHECKED LIMITS ORI MAT .080, REMOVED MAT .001, REMAINING .079 FOUND TO BE WITHIN LIMITS IAW B737-MAX9 SRM 53-30-01-01-1, SRM 53-00- 01-1A-5. ALODINE APPLICATION'S IAW B737-MAX9 SRM 51-20-01. APPLIED PRIMER IAW SOPM 20-41-02. APPLIED TOPCOAT IAW B737-MAX9 AMM 51-21-99/201. REMOVED AND REINSTALLED FUSELAGE DRAIN VALVE STA 400 BL0 IAW B737-MAX9 AMM 53-31-03-000-801, AMM 53-31-03-400-801.