FLC OF MLG ACR ACFT INADVERTENTLY DEACTIVATED THE REMAINING ENG REVERSER AFTER FOLLOWING INSTRUCTIONS FROM THE COMPANY MAINT CTLR.

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I WORK AS A SYS ACFT MAINT CTLR (SAM) IN SAN FRANCISCO; CA; AND ROUTINELY PROVIDE ASSISTANCE TO FLCS AS PROBS DEVELOP WITH ACFT INFLT OR ON THE GND. I WAS INVOLVED IN A SIT THAT RESULTED IN A CONDITION WHICH AFFECTED THE GND OPERATIONAL PERFORMANCE OF AN MLG A ACFT ON LNDG AT SEATTLE ON FLT XXX; MAY/XX/93. THE ACFT LANDED AND RPTED THE #2 ENG REVERSER DID NOT DEPLOY ON LNDG. (FOR INFORMATIONAL PURPOSES; THE #1 ENG REVERSER SYS HAD BEEN DEFERRED INOP ON MAY/XX/93 AT MSY AND SHOULD HAVE BEEN DEACTIVATED PER SPECIAL PROC). I HAD RECEIVED A RADIO CALL FROM FLT AFTER DEP AT DENVER. THE CREW RPTED THEY HAD AN 'ENG' LIGHT ON THE FORWARD PANEL 6 PACK ANNUNCIATOR MODULE WHEN THE RECALL CHK WAS DONE. NO OTHER ENG ASSOCIATED FAULTS WERE OBSERVED OR RPTED. THIS LIGHT COULD HAVE BEEN CAUSED BY AN ENG REVERSER FAULT CONDITION. WHEN I REVIEWED THE ACFT CURRENT DEFERRED ITEMS; I SAW THAT THE #1 ENG REVERSER WAS INOP. I ASKED THE CREW TO CHK AND SEE IF THE ENG REVERSER CTL CIRCUIT BREAKER WAS PULLED ON THE PANEL AS REQUIRED BY THE INOP REVERSER PROC. THE CREW ADVISED THAT NO CIRCUIT BREAKERS WERE FOUND OUT. TO COMPLY; I ADVISED THE CREW TO PULL THE ENG CTL CIRCUIT BREAKER AT GRID LOCATION C-6. I HAD DETERMINED THIS CIRCUIT BREAKER LOCATION USING THE MLG QUICK REF CIRCUIT BREAKER DIAGRAM FOR AN MLG B ACFT. I ASSUMED THAT THIS WAS THE CORRECT CIRCUIT BREAKER FOR THE #1 ENG REVERSER CTL SYS. THE CIRCUIT BREAKER IS NOT IDENTED BY ENG POS AND BEING LOCATED ON THE L SIDE OF THE PANEL AS VIEWED; ONE MIGHT ASSUME THAT IT WOULD BE FOR THE L OR #1 ENG. THE CREW DID NOT RPT ANY FURTHER PROBS WITH THE 'ENG' LIGHT SO I THOUGHT THE SIT HAD BEEN CORRECTED. I THEN CONTACTED SEATTLE MAINT AND REQUESTED THAT THEY CHK THE ACFT ON ARR AND CONFIRM THAT REVERSER DEACTIVATION PROCS HAD BEEN COMPLIED WITH. SEATTLE MAINT FOUND THAT THE #1 ENG REVERSER CTL CIRCUIT BREAKER HAD NOT BEEN PULLED AS SPECIFIED. THE #2 REVERSER CIRCUIT BREAKER; HOWEVER; WAS FOUND OUT AND WAS THE REASON THAT THE #2 REVERSER DID NOT DEPLOY ON LNDG. IN THE FUTURE I PLAN TO EXERCISE MORE CAUTION WHEN RESEARCHING AND ADVISING CIRCUIT BREAKER LOCATIONS AND HOPE THIS SIT WILL NOT RECUR. I FEEL; HOWEVER; THAT FLCS HAVE SOME RESPONSIBILITY IN THIS TYPE OF A SIT TO CHALLENGE AND CONFIRM THESE ACTIONS AS WELL AS BE AWARE OF THE MAINT STATUS OF THEIR ACFT.