3527 During train prep-Found air dryer f ~~~~~ 3527 During train prep-Found air dryer fault. To further rectify.  3527-Replaced air dryer. Security checked -OK.Monitor air dryer.Function OK. Able to interval air purge .No air dryer fauly indication.Conducted air leak test -OK. (Reading 0.4 bar/5 mins.) (Old s/n:3515020254) (New s/n:3514100103) Fadly/Faiz/Farid/Redzwan 44521