What was found
AIRCRAFT WAS GROUNDED: AT MIA DURING TAXI OUT, AIRCRAFT BEHIND REPORTED SMOKE FROM THE APU. FLIGHT RETURNED TO GATE UNDER ITS OWN POWER. ARFF CALLED AND FOLLOWED TO GATE. ARFF COOLED APR WITH WATER AT MAINTENANCE REQUEST. MAINTENANCE PERFORMED FIVE OPS CHECKS OF APU PERFORMANCE AND INSPECTED LAU COMPARTMENT FOR ABNORMALITIES IAW AMM 49-11-00 AND 49-11-01. ALL CHECKS GOOD. OK FOR SERVICE.