What was found
FLT 5423 - WHEN FLAPS WERE SELECTED TO 25 DEGREES, RECEIVED A FLAPS MESSAGE FOLLOWED BY LOSS OF BLUE HYDRAULIC SYSTEM FLUID. REPLACED THE RIGHT NACELLE ACTUATOR IAW AMM 27-50-08. OPS AND LEAK CHECKS GOOD, P/N: 343100-1001 S/N OFF: 0200.