MECHANIC USES A MAINT PROCEDURES MANUAL TO DEFER A B737-800 FIRST OFFICER'S FOOT AIR CONTROL KNOB AS NON-ESSENTIAL; BUT LATER REALIZES A RECENT REVISION TO THE MEL LIMITED DEFERRAL TO TEN DAYS.

Narrative

FLT CREW CALLED FROM ACFT TO NOTIFY MAINT CTL CTR; B737 MAINT COORDINATOR'S DESK; THAT THE FO'S FOOT AIR CTL KNOB BROKE. AS IN YRS PAST; I ISSUED A FLT CREW PLACARD PER COMPANY PROCS USING A GENERIC MEL NUMBER TO GENERATE A CTL NUMBER TO COVER THE MISSING KNOB. THE MISSING KNOB REMAINED ON DEFERRED STATUS FOR APPROX 2 MORE WKS. ANOTHER ACFT HAD A SIMILAR PROB AND DISCOVERED THAT THERE WAS A SPECIFIC MEL TO COVER THIS DISCREPANCY THAT WAS ADDED AT THE LAST MEL REVISION. THE REPAIR CATEGORY FOR THIS ITEM IS 10 DAYS; SO CONSEQUENTLY THE FO'S FOOT AIR CTL KNOB DEVELOPED A REPAIR OVERRUN. ONCE DISCOVERED THE ACFT WAS STOPPED TO BE REPAIRED. ONE SUGGESTION TO AVOID A SIMILARSITUATION WOULD BE TO INCLUDE A LIST TO HIGHLIGHT THE CHANGES WHEN THE REVISED MEL IS RELEASED. CALLBACK CONVERSATION WITH RPTR REVEALED THE FOLLOWING INFO: REPORTER STATED THAT JUST RECENTLY THEIR B737-800 MEL WAS COMPLETELY REVISED. BUT; THE REVISIONS ARE NOT HIGHLIGHTED; MAKING THE CHANGES DIFFICULT TO NOTICE. THEIR MEL IS FULLY ELECTRONIC.