What was found
FL330, LOST STANDBY AIRSPEED INDICATORS, DIVERTED. DESCENDING THROUGH APPROXIMATELY FL250 IN VMC INDICATIONS APPEARED NORMAL. BACK FLUSHED DEBRIS FROM STANDBY AIRSPEED PITOT SYSTEM WITH DRY NITROGEN. RECONNECTED LINES AND PERFORMED SYSTEM OPS AND LEAK TEST IAW MM 34-10-00-0501.