AN EMB135 WAS DISPATCHED WITH THE FO'S STEERING DISENGAGE SWITCH DEFERRED IN CONFLICT WITH THE MEL.

Narrative

THE FO AND I DISCOVERED THAT THE PLASTIC COVER ON THE FO'S STEERING DISENGAGE BUTTON HAD POPPED OFF WHILE AT THE GATE IN ZZZ. MAINT REPLACED THE ENTIRE SWITCH BUT WE FOUND THAT THE NEW SWITCH WAS NOT WORKING PROPERLY. MAINT TRIED TO FIX THE SWITCH BUT WAS UNSUCCESSFUL. MAINT THEN DECIDED TO DEFER THE FO'S STEERING DISCONNECT UNDER MEL. I READ THE MEL AND NOTICED THE WORDING WITHIN THE DEFERRAL WAS INCONSISTENT BUT CONTINUED WITH MAINT'S APPROVAL AND SIGNOFF. WE DEPARTED AND COMPLETED THE FLT NORMALLY. SAFETY IS PARAMOUNT AND WAS NOT JEOPARDIZED IN THE LEAST. IN THE DAYS THAT FOLLOWED I BECAME AWARE THAT MAINT BELIEVED THAT THIS MEL AND COURSE OF ACTION WAS INAPPROPRIATE GIVEN THE SITUATION. I WAS TOLD THAT THE INTENT OF THE MEL IS TO DEFER ONLY THE CAPT'S STEERING DISENGAGE BUTTON. I BELIEVE THE MEL IS AMBIGUOUS AND MISLEADING AT BEST CONCERNING THIS SITUATION. MOST OF THE TIME; THE MEL IS SPECIFIC IN WHAT CAN AND CAN'T BE DEFERRED. THE ITEM DESCRIPTION FOR THIS READS; 'CTL WHEEL STEERING DISENGAGE BUTTONS' (PLURAL); NOT 'CAPT'S CTL WHEEL STEERING DISENGAGE BUTTON' AS IS THE INTENT. FURTHERMORE; THE WORDING IN THE REMARKS AND FLT CREW OPERATING PROCS SECTIONS REFER TO 'PLT' AND 'COPLT' INSTEAD OF 'CAPT' AND 'FO' OR 'PF' AND 'PNF.' ZZZ1'S REVISED ABNORMAL CHKLIST 'UNCOMMANDED SWERVING ON GND' DIRECTS THE USE OF THE STEERING DISENGAGEMENT BUTTON. I BELIEVE IT WOULD BE BEST TO HAVE THE 'PF' COMPLETE THIS SECTION. IN ORDER TO PREVENT THIS CONFUSION IN THE FUTURE; I THINK THE MEL SHOULD BE MORE SPECIFIC IN WHICH STEERING DISENGAGE BUTTON IS DEFERRABLE AND THE APPROPRIATE ACTIONS TO BE TAKEN; IE; WHO IS GOING TO BE PF OR PNF.