http://www.faa.gov/ATPubs/AIM/Chap5/aim0504.html#5-4-9 5-4-9. Procedure Turn
a. A procedure turn is the maneuver prescribed to perform a course reversal to establish the aircraft inbound on an intermediate or final approach course. The procedure turn or hold in lieu of procedure turn is a required maneuver when it is necessary to perform a course reversal. The procedure turn is
not required when the symbol
"No PT" is shown, when
RADAR VECTORING to the final approach course is provided, when conducting a
timed approach, or
when the procedure turn is not authorized. The hold in lieu of procedure turn is not required when RADAR VECTORING to the final approach course is provided or when "No PT" is shown.