MD80S ACFT WITH ENG AND WING ANTI-ICE ON AND MAX CONTINUOUS THRUST SELECTED RPTR FO SAYS THAT THE NO MODE LIGHT DIDN'T ILLUMINATE AS IT SHOULD ACCORDING TO THE ACR OPERATING MANUAL.

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DURING CLB WITH ENG ANTI-ICE ON; WING ANTI-ICE ON; AND PNEUMATIC XFEED VALVES OPEN; MAX CONTINUOUS THRUST SELECTED AND NO MODE LIGHT ILLUMINATED. LATER DURING CRUISE; IT WAS DISCOVERED THAT WITH ENG AND WING ANTI-ICE ON AND BOTH PNEUMATIC VALVES CLOSED THE NO MODE LIGHT DID NOT ILLUMINATE PER THE OPERATING MANUAL. THIS DISCREPANCY WAS ENTERED INTO THE LOG. I FOLLOWED UP WITH TECHNICIAN AND THEY INDICATED THAT WITH MAX CONTINUOUS THRUST SELECTED AND THE AIRFOIL ANTI-ICE ON AND BOTH PNEUMATIC XFEEDS CLOSED YOU WILL NOT GET A NO MODE LIGHT. I CONFIRMED THAT THIS WAS TRUE ON EACH AND EVERY ACFT THAT I HAVE CHKED SINCE. I BROUGHT THIS DISCREPANCY TO ATTN OF FLEET SPECIALIST FLT TECHNICIAN. HE INITIALLY CHKED IT ON A SIMULATOR AND CONFIRMED MY FINDINGS. AFTER MY REPEATED CALLS OVER A 3 MONTH PERIOD HE INFORMED ME THAT A REVISION WAS NOT PENDING AND HE HAD BEEN TOLD THAT THE OPERATING MANUAL WAS CORRECT. THIS DOES NOT INVOLVE INTERP. IT IS EITHER RIGHT OR NOT. IF THE OPERATING MANUAL IS CORRECT THEN MOST; IF NOT ALL; OF THE S80 ACFT DO NOT OPERATE PROPERLY.