Summary
The FAA proposes to supersede an existing airworthiness directive (AD) for certain McDonnell Douglas series airplanes. That AD currently requires repetitive inspections of the electrical connectors of the explosive cartridge wiring of the engine fire extinguisher containers to verify if the identification number labels are installed and legible; repetitive electrical tests of all explosive cartridge wiring of the engine fire extinguisher containers to verify proper installation and function; and corrective actions if necessary. This proposed AD would also require an inspection of the emergency shut off wire assembly; installation of lanyards on the electrical connectors for the engine fire extinguishing agent containers and for the auxiliary power unit fire extinguishing agent containers if applicable; and related investigative/corrective actions, as applicable. This proposed AD is prompted by reports of cross-wired electrical connectors of the engine fire extinguishing agentcontainers. We are proposing this AD to detect and correct cross-wired electrical connectors of the fire extinguishing system, which could release fire extinguishing agent into the incorrect engine nacelle in the event of an engine fire.