49 CFR 233.7: Signal failure reports.

Each carrier shall report within 15 days each failure of an appliance, device, method, or system to function or indicate as required by part 236 of this title that results in a more favorable aspect than intended or other condition hazardous to the movement of a train. Form FRA F6180-14, “Signal Failure Report,” shall be used for this purpose and completed in accordance with instructions printed on the form.