Airworthiness Directives; McDonnell Douglas Model DC-9-10, -20, -30, -40, and -50 Series Airplanes; and C-9 Airplanes

This amendment adopts a new airworthiness directive (AD), applicable to McDonnell Douglas Model DC-9-10, -20, -30, -40, and -50 series airplanes; and C-9 airplanes that requires replacing the transformer ballast assembly in the pilot's console with a new, improved ballast assembly. The actions specified by this AD are intended to prevent overheating of the ballast transformers due to aging fluorescent tubes that cause a higher power demand on the ballast transformers, which could result in smoke in the cockpit. This action is intended to address the identified unsafe condition.