B747 CREW EXCEEDED EGT LIMITATIONS ON A FULL THRUST PWR CHK ON TKOF.

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DESCRIPTION OF EVENT: IN CONNECTION WITH A MAINT C CHK; WE WERE REQUESTED TO PERFORM A 'MAX PWR' TKOF FROM HKG (HONG KONG). WITH AN OUTSIDE TEMP OF 31 DEGS C; WE EXPECTED TO SEE YELLOW RIBBONS ON THE EGT READOUT OF THE EIDS (ENG INDICATING DISPLAY SYS) INDICATING TEMPS NEAR MAX LIMITS. OUR PROCS CALLED FOR ME (THE PF); TO ADD PWR CLOSE TO THE DESIRED EPR; AND FOR THE FE TO MAKE THE FINAL ADJUSTMENT. I OBSERVED THE EPR'S APCH THEIR TARGETS FOR TKOF AND 2 EGT RIBBONS TURNED YELLOW AS EXPECTED. SHORTLY THEREAFTER I WAS ALERTED BY MY FE TO THE FACT THAT #1 AND #2 ENG EGT RIBBONS HAD TURNED RED. I NOTED THAT THE EPR'S WERE AT OR NEAR TARGET AND FELT THE FE RETARDING THE PWR LEVERS. I ELECTED TO CONTINUE TKOF RATHER THAN RISK AN ABORT. OUR WORKLOAD PREVENTED US FROM RECORDING ENG PARAMETERS. SINCE ALL INDICATIONS APPEARED NORMAL; WE CONTINUED OUR FLT TO KHV (KHARBAROVSK). ONCE ENRTE; WE SWITCHED THE EIDS TO DIGITAL ON THE L SIDE AND SELECTED 'RCL' FOR EXCEEDANCE REVIEW. THE SCREEN READ: 'NO EXCEEDANCE RECORDED.' THIS APPEARED TO BE INCONSISTENT WITH THE EGT; WHICH STILL HAD 'RED BALLS' FOR ENGS #1 AND #4. SINCE THE EIDS EGT TAPE GAUGE IS DIFFICULT TO READ PRECISELY DURING TKOF; WE UNDERESTIMATED THE MAGNITUDE AND DURATION OF THE EXCEEDANCE. MOREOVER; OUR ONBOARD MANUALS DO NOT CONTAIN INFO ON EXCEEDANCE MAINT LIMITATIONS. DUE TO POOR COMS IN THIS REGION; WE WERE UNABLE TO REACH MAINT CTL FOR GUIDANCE. WITH AMBIGUOUS INDICATIONS ON THE EXCEEDANCE AND NO GUIDANCE FROM EITHER HOME BASE OR ONBOARD MANUALS; I ELECTED TO DEPART KHV FOR ANC (ANCHORAGE) BELIEVING WE HAD SUFFICIENT FLT TIME ALLOWANCE BEFORE AN INSPECTION MUST BE PERFORMED. IT WASN'T UNTIL WE WERE ENRTE FROM KHV TO ANC THAT WE WERE ABLE TO CLARIFY BY MEANS OF THE EIDS THAT AN EXCEEDANCE HAD ACTUALLY OCCURRED. FOR SOME REASON; WHEN WE DISPLAYED THE DIGITAL SCREEN IN THE R HAND SIDE OF THE EIDS INSTEAD OF THE L HAND SIDE AS BEFORE; SELECTING RCL INDICATED THE MAX TEMP; DURATION AND MAINT CATEGORY CODE FOR THE EXCEEDANCE. SINCE THE EIDS MANUAL DOES NOT SHOW ANY FUNCTIONAL DIFFERENCE BTWN THE L AND R DISPLAY; I DO NOT KNOW WHY WE EXPERIENCED A DIFFERENCE IN READOUT. WE WERE ALSO ABLE TO RAISE MAINT CTL ON THIS LEG VIA COMMERCIAL RADIO ON HF TO RPT THE INCIDENT. THE EIDS IS NEW TO OUR FLEET OF B747'S. ALTHOUGH I WAS TRAINED ON THIS SYS IN SEPT 1999; I HAD ONLY OPERATED EIDS EQUIPPED ACFT A FEW TIMES SINCE THEN AND NEVER EXPERIENCED AN EXCEEDANCE CONDITION.