As reported to the FAA. Reports are unverified, and codes are left as the FAA publishes them.
What was found
AIRCRAFT WAS GROUNDED. PASSING FL 350, THE STANBDY AIRSPEED STARTED ROLLING BACK FROM MATCHING OTHERS AT 260KT TO SETTLE AT 105 KTS AND REMAINED THERE, ALTITUDE INDICATION WERE NORMAL. BEGAN TO RETURN TO NORMAL IN DESCENT PASS THRU FL 250 NORMAL BY FL 200. REPLACED AUX PITOT PROBE AND ACCOMPLISHED A SATSIFACTORY OPERATIONAL CHECK, PER AMM 34-11-01.