What was found
PHX - FLT NR 417 - PHX/COS - AIR TURN BACK - AIRCRAFT ROLLED TO THE LEFT AND REQUIRED 15 TO 20 DEGREE RIGHT AILERON TO CORRECT. SITUATION CORRECTED AFTER FLAPS RETRACTED. AIRCRAFT LANDED WITHOUT INCIDENT. MAINTENANCE FOUND NR 5 LEADING EDGE SLAT AUXILLIARY TRACK FITTING MOUNT HOLES TO BE ELONGATED. REMOVED AND REPLACED NR 5 SLAT. AIRCRAFT RETURNED TO SERVICE. (M)