What was found
DURING TAKEOFF, NR 1 ENGINE FIRE WARNING LIGHT ILLUMINATED WITH NO SECONDARY INDICATIONS. ACFT LANDED IMMEDIATELY BACK AT MAINTENANCE RAMP. THE NR 1 AFT, UPPER, FIRE DETECTOR WAS REPLACED AND DOCUMENTED ON LC-000594-88-16, DISC-000542-88-16. SUPPLEMENTAL INFORMATION; THE DETECTORS IN THIS A/C HAVE BEEN REPLACED WITH P/N 477223 FLAME DETECTORS IAW COLUMBIA HELICOPTERS, INC. SERVICE BULLETIN NUMBER 107-26-S0004. DETAILS ARE ON FILE WITH OPERATOR CHIA823C.