What was found
POSSIBLE OZONE ENCOUNTER NO EICAS MESSAGES NO ABNORMAL AT 38,000 GOING THROUGH CLOUDS SUDDEN ACRID SMELL ENTERED ENTIRE COCKPIT/CABIN LASTING 2-4 MINUTES NO SIGNS OF FIRE BUT FOG LIKE PERMA INSPECTED AIRCRAFT INTERIOR FOUND NO DEFECTS. INSPECTED INLETS AND EXHAUST OF BOTH ENGINES NO DEFECTS. AFTER INSPECTING ENTIRE A/C SUSPECT POSSIBLE ENCOUNTER WITH VOLCANIC ASH DUE TO ACRID SMELL. PERFORMED VOLCANIC ASH CONDITION INSPECTION. NO DEFECTS NOTED AS PER 05-51-31-201, SMOKE QUESTIONER FAXED TO APPR DEP.