What was found
YAW DAMP, MACH TRIM DISENGAGED TWICE ON TAKEOFF ROLL. PITOT HEAT WAS ON FOR 5 MINUTES PRIOR TO SECOND TAKEOFF ROLL. PERFORMED OPS CHECK OF YAW DAMPNER ON FGC A AND B SIDES, FOUND NO DISCRECPENCIES. DOWNLOAD AFCS FAULTS AND MADC FAULTS AND MAILED TO TEAM X PRODUCT SUPPT. TEAM X, REPORTED NO YAW DAMPNER FAULTS FOUND BUT 2 MADC MIS COMP FAULTS FOUND CAUSED BY WATER IN PITOT TUBES. DISCONNECTED PITOT LINES FROM MADC'S AND PURGED OUT PITOT LINES AND PITOT TUBES FOR NR 1 AND NR 2 PITOT STATIC SYSTEMS. RECONNECTED PITOT LINES AND COMPLIED WITH PITOT LEAK CHECK IAW CITATION 750 MM CH 34-11-01. PITOT LEAK CHECK GOOD. PERFORMED OPERATIONAL CHECK OF FGC A AND B YAW DAMPNER SYS IAW MM AND OPS MANUAL, OPS CHECK GOOD.