AN MD11 ON APCH AT 10000 FT DECLARED AN EMER DUE TO A FALSE FIRE WARNING ON #3 ENG CAUSED BY A FAILED ENG FIRE DETECTION BOX. CREW WAS UNABLE TO DISCHARGE THE FIRE BOTTLES DUE TO FIRE HANDLE FORCE.

Narrative

APCHING NAGOYA ARPT; #3 ENG FIRE WARNING CAME ON. ACCOMPLISHED CHKLIST PROCS PER ACFT POM. ENG SHUT DOWN; FIRE HANDLE PULLED AND ATTEMPTED TO DISCHARGE FIRE BOTTLES AT 5 MIN INTERVALS (FIRE BOTTLE #1; THEN AFTER 5 MINS; FIRED SECOND BOTTLE). DID NOT GET AGENT LOW LIGHTS CONFIRMING BOTTLES WERE DISCHARGED. APPARENTLY MD11 REQUIRES EXCESSIVE FORCE TO DISCHARGE BOTTLES. DECLARED EMER; VISUALLY CHKED ENG FROM CABIN AND NO APPARENT FIRE. LANDED WITHOUT EVENT. MAINT FOUND FIRE DETECTION BOX FOR #3 ENG FAULTY AND REPLACED IT. BOTTLE FIRING MECHANISM WAS VERIFIED IN WORKING ORDER AND ACFT WAS DISPATCHED BACK TO ZZZ VIA PORTLAND; OR. MAINT IN ZZZ TOOK ACFT TO HANGAR AND DISCHARGED BOTTLES FROM COCKPIT TO FURTHER VERIFY THAT ENG FIRE PANEL WAS WORKING CORRECTLY. AGAIN IT SEEMS THAT THE MD11 ACFT REQUIRES AN EXCESSIVE AMOUNT OF FORCE TO DISCHARGE FIRE BOTTLES. CALLBACK CONVERSATION WITH RPTR REVEALED THE FOLLOWING INFO: THE RPTR STATED THE POM WAS USED TO SHUT DOWN THE ENG; AND DISCHARGE THE ENG FIRE EXTINGUISHER. THE RPTR SAID DURING THE EMER THE FIRE HANDLE WAS PULLED DOWN SHUTTING OFF PNEUMATICS; ELECTRICAL PWR; HYDS AND FUEL THEN ROTATED TO FIRE THE ENG FIRE BOTTLES. THE RPTR STATED WHEN THE HANDLE WAS ROTATED THE BOTTLES DID NOT FIRE AS NO BOTTLE LOW PRESSURE WARNING LIGHTS WERE ILLUMINATED AND LATER IT WAS FOUND 26 LBS OF HANDLE ROTATIONAL FORCE WAS REQUIRED. THE RPTR SAID THE SIMULATOR ROTATIONAL FORCE WAS MUCH LESS AND NO WHERE NEAR THE ACTUAL AIRPLANE. THE RPTR SAID THE CARRIER ISSUED AN IMMEDIATE ALERT BULLETIN COVERING THE ROTATIONAL FORCE REQUIRED.