What was found
POTABLE WATER SYSTEM SERVICED TO FULL, BUT INDICATIONS SHOW 3 QTR. SERVICED TO FULL, INDICATIONS INOP IN CABIN AND SERVICE PANEL. WHEN CLEARING DEFER ITEM REMOVE DF-CF PLACARD FROM INTERIOR OF BOTH POTABLE WATER SERVICE PANEL. ALL QTY INDICATORS SHOWS 3 QTR, WITH TANKS FULL. MAY REQUIRE SUMMATION UNIT M38004, (566-0143). 1EA 566-02143 RCS 769-56M AT SFOJL HB. REPLACED SUMMATION UNIT 3-23-11, NO HELP. STILL SHOWS 3 QTR FULL. CTR TANK TRANSMITTER WILL NOT CALIBRATE. L+R CALIBRATED. TRANSMITTER 483-2065 IS LOB AFT PIT. WILL NEED TEST CABLE 926-3500 FOR QTY ADJ AFTER TXMTR REPLACED. IF UNABLE TO CALIBRATE REPLACEMENT TRANSMITTER, KNOWN FLEETWIDE ISSUE OF INTERIOR TANK DETERIORATION SUSPECTED. TANK PCN 12