What was found
LEFT WING BLEED LEAK. LEFT WING BLEED LEAK IN CRUISE. FLIGHT RETURNING TO DEN DUE TO ICING AND WX. FOUND VERY LARGE LEAK ON THE RT PACK OZONE CONVERTER AFT CLAMP, REMOVED CLAMP RE-ADJUSTED SEAL AND SECURED CLAMP, LEAK WAS BLOWING AT OVERHEAT LOOP ON KEELBEAM AREA, RAN PACKS AND WAI TEST MANY TIMES COULD NOT GET TO FAIL.