What was found
AIRCRAFT WAS NOT GROUNDED: FUMES IN FLIGHT DECK AND CABIN FORCED RETURN TO PHX. MAINTENANCE FOUND APU AS THE CAUSE, COMPLIED WITH 26L00021001, 26L00021002, 26L00021004, AND PERFORMED SUCCESSFUL OPERATIONAL CHECK. REPLACED APU STARTER PER MM 49-42-51, COMPLIED WITH APU WASH PER MM 49-00-00-100-001-A NO LEAKS FOUND.