A MD80 ON CLBOUT; CREW DISCOVERED #1 AND #2 FLT GUIDANCE SYS WOULD NOT ENGAGE AND MOMENTARY YAW DAMPER PROBS. CAUSED BY BROKEN WATER LINES.

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JUST PRIOR TO DEP; THE AFT LAVATORY SMOKE DETECTOR CHIME STARTED GOING OFF LIKE CRAZY. ACFT MAINT WAS RIGHT THERE AT THE FORWARD ENTRY. HE CHKED OUT THE PROB AND PLACARDED THE AFT L LAVATORY. IN THE MEANTIME; I WENT IN THE FORWARD LAVATORY AND FOUND VERY LITTLE WATER COMING OUT OF THE LINES. NO BIG DEAL. NOW; DURING CLBOUT; I WENT TO TURN ON THE AUTOPLT; AND IT WOULD NOT ENGAGE. SWITCHED OVER TO DFGS C2; AND IT STILL WOULD NOT ENGAGE. MOMENTARILY; THE RUDDER WAS ACTING UP LIKE THERE WAS NO YAW DAMPER. THIS PROB WAS SHORT LIVED. I WOUND UP HAND FLYING THE REST OF THE LEG TO ZZZ1. A SHORT WHILE LATER; THE FLT ATTENDANTS RPTED NO WATER AT ALL IN THE LAVATORIES OR GALLEYS. UPON ARR IN ZZZ1; THE AWAITING MECH SAID THAT YESTERDAY THE WATER LINES IN THE ACFT FROZE; THEN BROKE; AND WATER WENT ALL OVER. MY FO DID A POSTFLT WALKAROUND AND FOUND CHUNKS OF ICE UNDER THE ACFT; AND THE RAMP GUYS WERE UNABLE TO OPEN THE AFT CARGO DOOR. ALL OF THE ZZZ1 MECHS NOW KNEW THE PROB; AND THAT A WATER LEAK WAS MOST LIKELY THE COMMON DENOMINATOR.