A DC9-50 WAS DISCOVERED DURING A HVY CHK TO HAVE THE R ENG FUEL HEAT SYS IMPROPERLY WIRED. SYS WAS INOP WITH NO LOG RPTS.

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ACFT CAME INTO CHK WITH THE R-HAND FUEL HEAT INOP. FOR HOW LONG NO ONE COULD KNOW AS THERE IS NO LINE OR PREFLT CHK TO DETERMINE THIS. WIRE 2H103C24 WAS IN FACT WIRED TO A 115VAC BUS; RENDERING RELAY R2-129 'FUEL DEICING INDICATION R' INEFFECTIVE. I MOVED W2H103C24 FROM B1-48 'R FUEL HEAT CTL' TO BREAKER B1-50 'FUEL HEAT ADVISORY R' WAM REF 73/11/00 PAGE 12 REVISION A 5/XA/94. I TROUBLESHOT R-HAND FUEL HEAT BASED ON WPM 73/11/00 AND FOUND IT IMPOSSIBLE TO MAKE THE COCKPIT INDICATION OPERATE PER MAINT MANUAL WITH SHOWN CIRCUIT; UNLESS W2H116A24 WAS MOVED FROM A3 POS TO A1 POS ON R2-129 AND W2H105C24/W2H105E24 -- AND W2H106A24 WERE MOVED FROM A3 TO A1 ON RELAY R2-65. THIS THEN ALLOWED ALL COCKPIT FUNCTIONS AND LIGHTS TO WORK AS STATED. THE ACFT CAME INTO CHK IN THIS CONDITION. THE FUEL HEAT COULD NOT HAVE BEEN OPERATING CORRECTLY. CALLBACK CONVERSATION WITH RPTR REVEALED THE FOLLOWING INFO: THE RPTR STATED THIS AIRPLANE WAS PURCHASED FROM ANOTHER ORGANIZATION AND THE HVY CHK WAS THE FIRST ONE FOR THE PRESENT OWNER. THE RPTR SAID THERE WAS NO PAPERWORK TRAIL TO DETERMINE WHERE OR WHEN THE R ENG FUEL HEAT CIRCUIT WAS WIRED. THE RPTR STATED THERE WAS NO WAY THIS SYS COULD HAVE BEEN OPERATED OR BE TESTED THE WAY IT WAS WIRED.