What was found
ACFT WAS ON A REPOSITIONING FLIGHT. APPROX 1 HR INTO FLIGHT, ATC CLEARED ACFT FROM FL390 TO FL240 AND A DESCENT OF 3000 FPM WAS STARTED. AFTER A FEW MINUTES INTO DESCENT BOTH PFD AIRSPEED TAPES FAILED. CREW NOTED POSSIBLE PITOT TUBE ICING AND TOOK EMERGENCY ACTION TO INCLUDE DECLARING AN EMERGENCY WITH CTR AT FL220 ALL PFD INDICATION RE-APPEARED ON BOTH PFD`S AND ALL WARNING FLAGS DISAPPEARED. CREW STATED THAT THEY UNDECLARED THE EMERGENCY WITH ATC AND MADE AN UNEVENTFUL LANDING. INSP OF PITOT HEATERS WAS ACCOMPLISHED, WITH NO DEFECTS NOTED. SUSPECT PITOT TUBE ICING DURING DECENT. (K)