What was found
GEG FLIGHT NR 2357: FLAP POWER CAUTION LIGHT ILLMINATED WHEN FLAPS WERE SELECTED DOWN AFTER START. AIRCRAFT RETURNED TO GATE. MAINTENANCE REMOVED THE FCU AND A SERVICEABLE UNIT WAS INSTALLED IAW Q400 AMM 27-51-01-000-801 AND 27-51-01-400-801. TRANSDUCER WAS REMOVED AND SERVICEABLE ONE INSTALLED IAW Q400 AMM 27-53-06-000-801 AND 27-53-06-400-801. FPU REMOVED AND SERVICEABLE UNIT INSTALLED IAW Q400 AMM 27-52-01-000-801 AND 27-52-01-400-801. NO DEFECTS NOTED AFTER FUNCTIONAL CHECKS. AIRCRAFT RETURNED TO SERVICE.