DURING A REQUIRED MAX THRUST TKOF A B747 CREW NOTES THAT 2 ENGS DO NOT PRODUCE THE REQUIRED THRUST. TKOF IS REJECTED AT 107 KTS.

Narrative

ON TKOF; MAX TKOF THRUST WAS SET (AS REQUIRED PER COMPANY FOM/FHB; 15 DAYS SINCE LAST PERFORMED. ONE REQUIRED AT MINIMUM; EVERY 15 DAYS). THE FO WAS THE PF. WHILE SETTING THE TKOF THRUST; THE FE ADVISED THAT HE WAS UNABLE TO OBTAIN THE REQUIRED TKOF THRUST ON THE #1 AND #3 ENGS. AT 107 KIAS; I ASSUMED CTL OF THE ACFT FROM THE FO (ANNOUNCING 'REJECT; I'VE GOT THE ACFT') AND COMMENCED A REJECTED TKOF. NO ENG PARAMETERS AND/OR ACFT LIMITATIONS WERE EXCEEDED AND ALL SECONDARY ENG INDICATIONS WERE NORMAL. THE ACFT WAS SECURED AND THE QRH; FHB AND BRAKE COOLING CHART WERE REVIEWED. THE FE ADVISED THAT THE #1 AND #3 ENG THRUST LEVERS WOULD NOT OBTAIN THE REQUIRED TKOF THRUST SETTINGS AT THEIR FORWARD MECHANICAL STOPS. THE #2 AND #4 ENGS WERE PRODUCING THE REQUIRED TKOF THRUST SETTING. THE #1 AND #3 ENG PARAMETERS WERE ENTERED IN THE ACFT MAINT LOGBOOK. NOTE: NORMAL THRUST (REDUCED) WAS NOT USED SINCE A MAX TKOF THRUST WAS REQUIRED ON THIS FLT LEG (IN ACCORDANCE WITH THE FOM/RHB PROCS). HOWEVER; THE #1 AND #3 ENGS WOULDN'T HAVE PRODUCED THE NORMAL THRUST SETTING; HAD IT BEEN USED.