What was found
CREW VERBAL REPORT PASSENGERS IN ENTIRE CABIN EXPERIENCED EYE IRRITATION AND NAUSEA DURING FLIGHT. NO SMOKE OR ODOR EVENT. A/C PACKS OPERATED NORMALLY. CONTACTED SFO HMC TO DEBRIEF CREW FOR ANY ADDITIONAL INFORMATION. DEBRIEFED CREW THE EVENT HAPPENED ON THE LAST QUARTER OF THE FLIGHT.F/A EXPERIENCED EYES AND NOSE IRRITATION ON THE F/A CREW REST AREA AND FORWARD CABIN.NO SMOKE OR ODOR NOTED. PILOTS DIDN'T EXPERIENCE ANYTHING ON THE FLIGHT DECK.A/C PACK WORKED NORMAL NO OVERHEAT. LOCKED FOR MX CONTROL DEBRIEF. INSPECTED ICS LEVELS FOR POSSIBLE LEAK. FOUND ICS AT NORMAL LEVELS. INSPECTED FWD OVENS AND FOUND DEBRIS CONSITENT WITH MASKING TAPE ADHERED TO INNER SIDE. FOUND BURNT DEBRIS INSIDE OF OVENS WELL. CLEANED AND REMOVED ALL DEBRIS. UNLOCKING FOR MX INSPECTED OVERHEAD FLIGHT CREW REST DUCT HEATER. FOUND PLASTIC FOD ON HEATING ELEMENT. REMOVED AND REPLACED DUCT HEATER. OPS CHECK GOOD. REF AMM 21-41-20