FLC MUST RETURN ETOPS FLT TO LAND OVERWT DUE TO BLEED OVERHEAT.

Narrative

DEP FROM JFK TO LISBON; PORTUGAL; AFTER MAINT ON 2 ITEMS. #2 ENG BLEED; #2 FADEC (ELECTRONIC FUEL CTL - THROTTLE LINK 'FULLY AUTOMATED DIGITAL ENG CTL'). THE ENG BLEED OP WAS REQUIRED FOR ETOPS (EXTENDED TWIN OPS) FLT OVER OCEAN AND WAS SUPPOSEDLY FIXED. THE FADEC WAS NOT REQUIRED AS LONG AS THE BACKUP SYS WAS OPERATING; AND WE WERE DISPATCHED WITH THE FADEC INOP WITH BACK UP MANUAL THROTTLES OPERATING; BUT WITH SEVERAL WT LIMITATION PENALTIES. 46000 LBS PLUS OR MINUS REDUCTION IN TKOF WT. LIMITED BY CLB AND 93000 LBS PLUS OR MINUS REDUCTION IN LNDG CLB PERFORMANCE WT. DURING CLBOUT THE #2 ENG BLEED OVERHEATED; AS IT HAD DONE BEFORE ON PREVIOUS FLTS SO WE COULD NOT CONTINUE ON OUR ETOPS FLT AND RETURNED TO JFK AND MADE AN OVERWT LNDG; WHICH IS NO PROB IN ITSELF AND IS MORE OR LESS STANDARD PROC AS THIS ACFT HAS NO FUEL DUMP SYS. THE DEGRADATION OF LNDG CLB LIMITS; HOWEVER; PUT US WELL ABOVE THE PERFORMANCE LIMIT OF THE ACFT; FOR SINGLE-ENG OPS; WHICH WOULD HAVE HAD MARGINAL PERFORMANCE IN THE EVENT OF AN ENG LOSS AND A MISSED APCH. THE ERROR WAS ONLY REALIZED AFTER THE FACT. A NORMAL 2 ENG LNDG WAS ACCOMPLISHED UNEVENTFULLY.