TC reported that TIMS showed air dryer fault. MR pressure was 10 bars. ~~~~~ 3501 TC reported that TIMS showed air dryer fault. MR pressure was 10 bars.  501/502 found FC 704 on both 3501 & 3502.    Replaced both air dryer on 3501 & 3502. Function test, brake pressure test & air leak test - All OK (refer to attached checklist). 3501 Air Dryer S/N : OLD : 351249009 NEW : 3515420001 3502 Air Dryer S/N : OLD : 015-13704 NEW : 3515460316  Chan GF/Alan/Alcus 43840