What was found
FLIGHT 502 PSP/LAS, THE FLIGHT CREW REPORT THAT THE STALL INDICATION FAILURE ANNUNCIATOR ILLUMINATED IN FLIGHT. THERE WAS NO STALL WARNING. PERFORMED QRH PROCEDURE TO DETERMINE SYSTEM 2 HAD FAILED. PULLED C/B Z-23. LAS VEGAS MAINTENANCE REPORT THE INTERROGATION OF THE STALL WARNING COMPUTERS AND BOTH REPORTED AOA VANE FAULT. REMOVED AND REPLACED AOA VANE PER AMM 34-19-01. NEXT DAY (04-01-2007) FLIGHT 551 RDM/LAS SIF, ANNUNCIATOR REPORTED AGAIN WITH SYSTEM 2 FAULT. LAS VEGAS MAINTENANCE REPORT THE REMOVAL AND REPLACEMENT OF THE NR 2 STALL WARN COMPUTER PER AMM 34-19-02. A SATISFACTORY OPERATIONAL CHECK WAS ACCOMPLISHED. THE AIRPLANE HAS RETURNED TO SERVICE.