Narrative:

Aircraft X was being dispatched with the automatic mode of the forward equipment cooling system inoperative. The MEL stated that departure in the standby mode was permissible. After takeoff, numerous electronic flight instrument failures and anomalies were observed, including ADI, HSI radar, autoplt malfunctions, etc. Our route to ZZZ1 included some convective WX and the forecast WX for ZZZ1 had recently changed and required us to add an alternate. With the multiple instrument failures and unsuccessful initial attempts to restore the instrumentation, as well as the WX we were likely to encounter, I elected to return to ZZZ. We presumed that the instrument failures/indication anomalies were associated with the equipment cooling deferral at original dispatch. We were fortunate to have a training captain from the training center to assist with problem assessment and communication. An emergency was declared in order to expedite handling at ZZZ. We ultimately re-established the cooling system temporarily and landed the aircraft uneventfully at ZZZ. I am a bit surprised that we experienced the equipment failures despite the MEL deferral. It was not a hot day in ZZZ, yet the MEL allows for operation with the automode of the equipment cooling system to be inoperative.

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Original NASA ASRS Text

Title: A B767-200 IN CLB AT 10000 FT DECLARED AN EMER AND DIVERTED DUE TO MULTIPLE INST FAILURES CAUSED BY INCORRECT DEFERRAL OF THE FORWARD EQUIP COOLING SYS AUTO MODE.

Narrative: ACFT X WAS BEING DISPATCHED WITH THE AUTO MODE OF THE FORWARD EQUIP COOLING SYS INOP. THE MEL STATED THAT DEP IN THE STANDBY MODE WAS PERMISSIBLE. AFTER TKOF, NUMEROUS ELECTRONIC FLT INST FAILURES AND ANOMALIES WERE OBSERVED, INCLUDING ADI, HSI RADAR, AUTOPLT MALFUNCTIONS, ETC. OUR RTE TO ZZZ1 INCLUDED SOME CONVECTIVE WX AND THE FORECAST WX FOR ZZZ1 HAD RECENTLY CHANGED AND REQUIRED US TO ADD AN ALTERNATE. WITH THE MULTIPLE INST FAILURES AND UNSUCCESSFUL INITIAL ATTEMPTS TO RESTORE THE INSTRUMENTATION, AS WELL AS THE WX WE WERE LIKELY TO ENCOUNTER, I ELECTED TO RETURN TO ZZZ. WE PRESUMED THAT THE INST FAILURES/INDICATION ANOMALIES WERE ASSOCIATED WITH THE EQUIP COOLING DEFERRAL AT ORIGINAL DISPATCH. WE WERE FORTUNATE TO HAVE A TRAINING CAPT FROM THE TRAINING CTR TO ASSIST WITH PROB ASSESSMENT AND COM. AN EMER WAS DECLARED IN ORDER TO EXPEDITE HANDLING AT ZZZ. WE ULTIMATELY RE-ESTABLISHED THE COOLING SYS TEMPORARILY AND LANDED THE ACFT UNEVENTFULLY AT ZZZ. I AM A BIT SURPRISED THAT WE EXPERIENCED THE EQUIP FAILURES DESPITE THE MEL DEFERRAL. IT WAS NOT A HOT DAY IN ZZZ, YET THE MEL ALLOWS FOR OP WITH THE AUTOMODE OF THE EQUIP COOLING SYS TO BE INOP.

Data retrieved from NASA's ASRS site as of July 2007 and automatically converted to unabbreviated mixed upper/lowercase text. This report is for informational purposes with no guarantee of accuracy. See NASA's ASRS site for official report.