What was found
ON TAKEOFF NR 1 ENG FIRE WARNING LIGHT ILLUMINATED WITH AUDIO, ACFT ENTERED RAIN SHOWER & APPROX 2 SECONDS LATER LIGHT EXTINGUISHED. NO FURTHER INDICATION OF FIRE. ACFT RETURNED TO DEPARTURE POINT. INSPECTED NR 1 FWD & AFT FLAME DETECTORS, CLEANED DETECTORS, CHECKED WIRING, TESTED SYS & ALL SYS CHECKED GOOD. PILOTS TESTED FIRE DETECTION SYS & SYS CHECKED GOOD, NO FURTHER FAULTS FOUND.