What was found
AT MAX POWER ON TAKEOFF, BAD BURNING ODOR IN THE AIR CONDITIONING SYSTEM, IN THE FRONT AND BACK CABIN AND COCPIT. PERFORMED ENGINES RUN-UP WITH AIRCRAFT CREW, RUN EACH PACKS ON AND BOTH OK WITH NOT ANY BURNING ORDER INDICATION AT THIS TIME. PRECAUTIONARY CHANGE COALESCER BAGS ON BOTH PACKS, IAW AMM 21-20-02 AND OPS CHECK GOOD. AIRCRAFT RETURNED TO SERVICE.