B747-400 FO RPTED A SUSPICIOUS DARK AREA VERBALLY TO DEP STATION MAINT. IT WAS NOT RECORDED IN WRITING IN THE ACFT DISCREPANCY LOGBOOK.

Narrative

DURING THE PREFLT; I NOTICED A DARK AREA JUST INBOARD OF THE R INBOARD AILERON. HOWEVER; THERE WAS NOT ENOUGH LIGHT; AND I WAS TOO FAR AWAY TO MAKE OUT ANY DETAIL (YOU MUST STAND RATHER FAR BACK IN ORDER TO SEE THE UPPER SURFACE OF THE WING ON THE B747 FROM THE GND). CHKING FROM THE MAIN DECK WAS NEVER A CONSIDERATION AS THE FREIGHTER 'VIEW PORTS' ARE USELESS WHEN WET. I TOLD THE MAINT GUYS (2) THAT THERE MIGHT BE A PANEL MISSING; BUT I WAS NOT SURE. THEY WENT OUT WITH THE CAPT TO LOOK WHILE I STAYED IN THE COCKPIT. I LATER LEARNED THAT THEY LOOKED UNDER THE WING; AND DECIDED THAT I WAS JUST LOOKING AT A DIFFERENCE IN PAINT COLOR. IN ANY CASE; THE MAINT TEAM RPTED 'NO PROB.' UPON ARR AT OUR NEXT STATION; THE MAINT LEAD INFORMED US THAT WE WERE MISSING A SECTION OF PANELING FROM THE UPPER SURFACE OF THE R WING. IN RETROSPECT; THE 'ASSUMES' GOT ME. I ASSUMED THAT THE MECHS WOULD BE CURIOUS AND TAKE A SERIOUS LOOK. THEY PROBABLY ASSUMED THAT I WAS JUST ANOTHER 'STUPID PLT.' IN THE FUTURE; I WILL ESCORT THEM TO MY AREA OF CONCERN.