Airworthiness Directives; McDonnell Douglas Model DC-9-32 Series Airplanes Modified Per Supplemental Type Certificate SA4371NM

This amendment adopts a new airworthiness directive (AD), applicable to all McDonnell Douglas Model DC-9-32 series airplanes modified per Supplemental Type Certificate SA4371NM, that requires an inspection to determine if certain ground wires on the water heater of each lavatory are installed, and corrective action, if necessary. The actions specified by this AD are intended to detect improper grounding of a water heater, which, coupled with an internal short in the water heater, could result in heat or smoke damage or a fire on the airplane. This action is intended to address the identified unsafe condition.