AN MD80 WAS DISPATCHED WITH MEL REQUIREMENTS FOR DEFERRAL OF GND EQUIP COOLING THAT CANNOT BE ACCOMPLISHED.

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OUR ACFT HAD THE CHK VALVES IN THE RADIO RACK COOLING SYS PLACARDED INOP. IT HAD OPERATED ON THIS PLACARD FOR 2 FLT DAYS. ON READING THE MEL ITEM 21-23B FOR THIS PLACARD; I SAW THAT ELECTRONICS WERE LIMITED TO A MAX OF 45 MINS OP ON THE GND. I THEN CHKED THE ON-TIME FOR THE PREVIOUS FLT AND SAW THE ACFT HAD BEEN ON THE GND FOR 1 HR 7 MINS. WE HAD NOT STARTED LOADING PAX YET. I MADE A LOGBOOK ENTRY STATING THE ELECTRONICS HAD BEEN OPERATING ON THE GND FOR OVER 1 HR ON OUR ARR AT THE ACFT. THE CIRCUIT BREAKERS FOR THE CHK VALVES H4; H5; H6; AND J4; J5; J6 WERE PULLED AND COLLARED SO NO NORMAL COOLING FLOW WAS PRESENT ON THE GND. MAINT CAME OUT AND AFTER TALKING TO THE MECHS AND MAINT CTLR AND THE MAINT SUPVR WE ALL AGREED THERE WAS NO WAY FOR A FLC TO SHUT OFF THE ELECTRONICS ON AN MD80 UNLESS ALL ELECTRICAL PWR WAS REMOVED FOR EACH PIECE OF EQUIP HAD ITS RESPECTIVE CIRCUIT BREAKERS PULLED. THE MAINT SUPVR TALKED WITH MAINT CTLR AND THEN PERFORMED A RETURN TO SVC CHK ON THE ELECTRONICS TO VERIFY IT WAS OPERATING PROPERLY. HE THEN CHKED THE OP OF THE CHK VALVES IN QUESTION AND VERIFIED THEY OPERATED PROPERLY AND REMOVED THE PLACARD. WE DEPARTED ALMOST 1 HR LATE. THE WORDING ON THIS MEL ITEM SPECIFICALLY STATES THAT ELECTRONICS ARE LIMITED TO 45 MINS OF GND TIME BUT DOES NOT GIVE ANY REFS OR GUIDANCE ON HOW TO TURN ANY ELECTRONICS OFF. SINCE THIS IS AN EFIS ACFT; THE QUESTION IS ALSO: DOES THE TERM 'ELECTRONICS' MEAN THE EFIS AS WELL AS THE PERFORMANCE COMPUTER; AND THE DFGCS COMPUTERS; AND THE RADIOS; ETC? CLRLY THIS SIMPLY STATEMENT OPENS MORE QUESTIONS THAN IT ANSWERS. FURTHERMORE; I MAINTAIN IT IS IMPOSSIBLE TO HAVE FLOWN THIS ACFT IN NORMAL OPS AND COMPLIED WITH THE PROVISIONS FOR ANY 2 CONSECUTIVE LEGS; MUCH LESS 2 DAYS WORTH OF FLYING. 45 MINS IS NOT ENOUGH TIME TO LAND; TAXI INTO A GATE; OFFLOAD PAX; LOAD PAX; TAXI OUT AND TAKE OFF. THIS ALSO ASSUMES THAT CATERING AND FUELING ARE DONE WITHIN THE TIME FOOTPRINT OF PAX UNLOADING AND LOADING AND NOT TAKING EVEN LONGER. THIS MEL ITEM IS CLRLY A WAY TO GET A BROKEN AIRPLANE OUT ON 1 LEG TO A MAINT BASE. EVEN MAKING THAT ASSUMPTION; IT IS POORLY WORDED. DEFINE WHICH ELECTRONICS SYS ARE AFFECTED AND TELL HOW TO SHUT THEM DOWN SO THE 45 MINS IS NOT EXCEEDED. CLRLY STATE A RESTR ON CONTINUED OPS IN THIS CONDITION. TO DO LESS IS TO SUBJECT FLC'S TO POSSIBLE ACTIONS AGAINST THEM FOR MEL VIOLATIONS. THIS IS AN UNSATISFACTORY SIT THAT REQUIRES AN MEL CHANGE. CALLBACK CONVERSATION WITH RPTR REVEALED THE FOLLOWING INFO: THE RPTR STATED THE MEL SPECIAL PROC REQUIRING GND OPS OF ELECTRONICS EQUIP BE LIMITED TO 45 MINS IS IMPOSSIBLE TO ACCOMPLISH. THE RPTR SAID THE PROC LISTS NO METHOD OF REMOVING PWR FROM THE INDIVIDUAL ELECTRONIC SYS EXCEPT PULLING CIRCUIT BREAKERS AS THIS AIRPLANE HAS NO RADIO MASTER SWITCH. THE RPTR STATED THIS AIRPLANE HAS AN EFIS SYS WITH CRT INSTS WHICH HAVE CRITICAL COOLING REQUIREMENTS. THE RPTR SAID THE COMPANY IS NOW MEETING WITH THE MANUFACTURER TO RESOLVE THIS PROB. THE RPTR STATED THE MEL WAS REVISED AND WILL NOT ALLOW DEFERRAL OF THE RADIO RACK COOLING FAN CHK VALVES.