What was found
SEA FLIGHT NR 2382: ON TAXI OUT, NR 2 PEC CAUTION LIGHT ILLUMINATED WITH ASSOCIATED POWERPLANT MESSAGE. NR 2 PROP RUNS AT 220 ON TAXI BACK TO GATE. MAINTENANCE REMOVED NR 2 ENGINE PCU IAW AMM 61-20-11-000-801 AND MTC 6610001 BETA TUBE REMOVAL. INSTALLED NR 2 ENGINE PCU IAW AMM 61-20-11-400-801. DURING ENGINE POWER ASSURANCE CHECK, BOTH BLEEDS NR 1 AND NR 2 HOT CAUTION LIGHT ILLUMINATED. PERFORMED OPS CHECKS. MAINTENANCE REMOVED AND REPLACED NR 1 HPSOV - P/N 820971-2. C/W PRATT AND WHITNEY POWER ASSURANCE CHECK NR 2 ENGINE PARAMETER RECORDING TABLE. ALL PARAMETERS CHECKED GOOD. AIRCRAFT RETURNED TO SERVICE.