What was found
AUTOFEATHER FAILED TEST. INDICATED A/F TEST FAILED ON #1, A/F TEST ABORT ON #2. CDS POSTED FAULT CODE 494 CHANNEL A &B ON BOTH ENGINES. C/W Q400 FIM TASK 61-20-10-810-826. FAULT CODE CLEARED. OP'S TEST OF THE PROPELLER AUTOFEATHER AND UPTRIM SYSTEM GOOD. REF Q400 AMM TASK 61-20-00-710-801. NO OTHER DEFECTS NOTED. A/C RELEASED FOR SERVICE. NEXT FLIGHT, AFTER TAKEOFF WE NOTICED THE "POWERPLANT" MSG ILLUMINATED, MONITORED THE ENGINES THROUGHOUT THE FLIGHT. NO ISSUES NOTED. REMOVED FROM SERVICE. REPLACED #1 PEC. POWERPLANT MSG EXTINGUISHED AND FAULT CODES CLEARED. OPS CHECK GOOD. RETURNED TO SERVICE