A LEAD MECHANIC DESCRIBES THE CONFUSION THAT LED HIM TO DEFER A BROKEN TRANSPONDER KNOB UNDER AN INCORRECT COM MEL; INSTEAD OF A NAV MEL PROCEDURE; ON CRJ-700 ACFT.

Narrative

AT ABOUT XA30 I CONTACTED MAINT CTL TO OPEN AN MEL ON ACFT X FOR A PLT WRITE UP EARLIER THAT NIGHT. THE WRITE UP WAS 'TXPONDER KNOB BROKEN;' OIL CHK AT THE GATE THE MECH WORKING THE AIRPLANE CAME TO ME ABOUT XA00 AND HANDED ME AN IPC REF; TELLING ME WE DON'T HAVE A TUNING UNIT OR THE INDIVIDUAL KNOB TO FIX THIS DISCREPANCY. MY RESPONSE WAS I WILL MEL IT. I CALLED MAINT CTL JUST A FEW MINS LATER TO OPEN THE MEL AND WAS INFORMED TO CALL BACK ABOUT XB30. THEY DIDN'T HAVE ENOUGH PEOPLE AT THAT TIME. WHEN I CALLED BACK I ASKED THE MAINT CTLR FOR MEL 23-37. BY LOOKING AT THE PICTURE IN THE IPC REF PROVIDED ME BY THE MECH IT LOOKED TO BE THE BACKUP TUNING UNIT THAT THE BROKEN KNOB WAS ON. AFTER DOING SOME LOOKING INTO THIS MATTER; THE ATC KNOB IS ON THE SAME PANEL AS THE BACK UP TUNING UNIT BUT IT WAS NOT THE TUNING UNIT ITSELF. BY LOOKING AT THE IPC THE KNOB PART NUMBER I PUT IN WAS THE CORRECT PART NUMBER NEEDED. HOWEVER THE IPC REF PICTURE SHOWS THE BACK-UP COM -- NAV TUNING UNIT AS ITEM 45 I BELIEVE AND THE KNOB IN QUESTION AS ITEM 85. BY THE PICTURE IT LOOKS LIKE THIS KNOB IS ATTACHED TO THE BACK-UP TUNING UNIT SO BY LOOKING AT THE PICTURE AND SEEING THE KNOB ON THE BACK-UP TUNING UNIT I MEL'ED THIS UNDER 23-37 BACK-UP COM -- NAV TUNING UNIT KNOB BROKEN; NOT FULLY REALIZING THE ORIGINAL WRITE UP WAS DIFFERENT FROM THE DEFERRAL. THE FUNCTION OF THE XPONDER WAS NOT AFFECTED IT WAS THE KNOB BROKEN; AND I WAS FOCUSING MORE ON THE PANEL THAT THE KNOB WAS ATTACHED TO. NOT PAYING ENOUGH ATTN TO REF MATERIAL GETTING CONFUSED ON REF MATERIAL. CALLBACK CONVERSATION WITH RPTR REVEALED THE FOLLOWING INFO: REPORTER STATED HE HAD MISTAKENLY DEFERRED THE BROKEN TRANSPONDER KNOB UNDER A CRJ-700 MEL FOR THE COM RADIO; INSTEAD OF AN MEL FOR THE NAV UNIT. A DOWNLINE STATION MAINT CORRECTED THE MEL ITEM AND REPLACED THE KNOB.