What was found
ENROUTE, F/AS REPORTED A STRONG BURNING RUBBER ODOR APPROXIMATELY ROWS 19 - 21,4 D.H. ODOR DISSIPATED. ACCOMPLISHED TROUBLESHOOTING CABIN AIR QUAILTY IAW J.C.26L00021001. RAN APU WITH BOTH PACKS ON FOR 20 MINS. NO ODOR FOUND. AIRCRAFT WAS GROUNDED.