Summary
The FAA proposes to adopt a new airworthiness directive (AD) for the McDonnell Douglas airplanes previously described. This proposed AD would require replacing the control modules of the fire detection systems of the propulsion engines with new, improved control modules. This proposed AD results from a report of broken or severed wiring between engine fire detectors and the fire detection system control module, which caused the fire detection system to become non-functional without flightcrew awareness. We are proposing this AD to prevent unannunciated fire in a propulsion engine, which could cause injury to flightcrew and passengers or loss of the airplane.