What must be done with inoperative equipment discovered prior to flight?

When inoperative equipment is discovered before a flight, it is essential to deactivate it and place a placard indicating that it is inoperative. This procedure is crucial for several reasons. First, ensuring that all onboard instruments and equipment are in proper working order is vital for the safety and efficiency of the flight. By deactivating the equipment, you prevent any potential confusion or misinterpretation of its status during the flight. The placarding serves to inform all crew members and any other personnel of the equipment's status, so everyone is aware that it is not functioning properly. This action is in line with regulatory requirements and standard operating procedures, which are designed to maintain a high standard of safety in aviation operations.