A B737-300 WAS DISPATCHED WITH AN APU PNEUMATIC DUCT LEAK IN THE AFT CARGO PIT SIDE WALL BUT LOGBOOK WRITE-UP AND SIGNOFF ALTERED TO ELIMINATE THE WORD 'LEAK.'

Narrative

THE EVENT BEGAN WHEN ACFT RETURNED TO THE GATE AND THE CAPT RPTED THE AFT GALLEY FLOOR VERY WARM TO THE TOUCH. CONTRACT MAINT WAS CALLED TO INSPECT THE AREA. DURING THAT TIME I ASKED THE CAPT IF HE HAD GOTTEN A L WING BODY OVERHEAT WARNING; AND HE SAID NO. I ASKED HIM TWICE AND HE SAID NO. HE TESTED THE SYS AND IT OPS CHKED NORMAL. THE CONTRACT MECH CALLED AND I ASKED HIM TO CHK THE AFT CARGO BIN SIDE WALL AND THE AREA BEHIND THE PRESSURE BULKHEAD FOR EXCESSIVE HEAT OR DISCOLORATION. I ALSO ASKED HIM TO SECURE THE APU AND SEE IF THE HEAT DISSIPATED AFTER HE COMPLETED HIS INSPECTION AND SAID HE FOUND NO LEAKS AND THE AREA COOLED WHEN THE APU WAS SHUT DOWN. I ASSUMED THAT AN INSULATION BLANKET ON THE APU AIR DELIVERY DUCT HAD SLIPPED (WHICH IS A COMMON OCCURRENCE) SO I DEFERRED THE APU UNDER MEL. THE LOGBOOK WAS SIGNED OFF AND THE FLT WAS CONTINUED. ON ARR IN ZZZ1 THE CAPT CALLED AND SAID HE WAS CONCERNED ABOUT THE WAY THE LOGBOOK WAS SIGNED OFF AND MAYBE WE SHOULD REINSPECT THE AREA. HE SAID THE FLT ATTENDANT HAD BEEN TOLD BY THE OPS AGENT WHO WAS TOLD BY THE CONTRACT MECH THAT THE ACFT HAD A DUCT LEAK. THE LOGBOOK WRITE-UP WAS FOR AN APU DUCT LEAK AND THE SIGNOFF WAS FOR AN APU DUCT LEAK AND THE ACFT RELEASE SHOWED AN MEL FOR AN APU DUCT LEAK. THE CAPT WANTED TO TALK TO HIS CHIEF PLT. A CONFERENCE CALL WAS SET UP BTWN THE CAPT; CHIEF PLT; DISPATCHER; CHIEF DISPATCHER; AND THE MAINT SUPVR. AFTER MUCH DISCUSSION; THE RELEASE WAS REVISED TO REMOVE 'DUCT LEAK' AND THE ACFT CONTINUED ON. UPON INSPECTION; A RUPTURED DUCT WAS FOUND IN THE AFT CARGO BIN SIDE WALL AND REPAIRED. ALSO; THE L WING BODY HEAT SYS WAS TESTED AND WORKED NORMALLY.