What was found
AUTOFEATHER DIDN'T ARM ON TAKEOFF IN SEATTLE. NOTICED AT V1, CONTINUED TAKEOFF. REMOVED FROM SERVICE. INTERROGATED CDF FOR FAULT CODES IAW Q400 AMM 77-31-00-710-803 FOUND FAULT CODES 494A B, 70AB, ON BOTH ENGINES, 398AB ON #2 ENGINE. COMPLIED WITH Q400 FIM PROCEDURE 61-20-08-810-818 FAULT CODES RESET COMPLIED WITH OPERATIONAL TEST OF PROPELLER AUTOFEATHER AND UPTRIM SYSTEM IAW 61-20-00-710-810 OF Q400 AMM REMAINING FAULT CODES CLEARED AFTER AUTO FEATHER PASSED, PERFORMED AUTOFEATHER TEST USING ENGINES AND ELECTRICAL MODE, PASSED IN BOTH. RECHECKED FAULT CODES NONE PRESENT. NO PARTS REPLACED. AIRCRAFT RETURNED TO SERVICE.