Airworthiness Directives; Boeing Model 747-200C and 747-200F Series Airplanes

We are adopting a new airworthiness directive (AD) for certain Boeing Model 747-200C and 747-200F series airplanes. This AD requires installing larger moisture shrouds and additional drain lines in the electrical/electronic equipment center. This AD results from reports of water contamination in the electrical/electronic units in the main equipment center. We are issuing this AD to prevent water contamination in the electrical/electronic units in the main equipment center, which could result in an electrical short and potential loss of several functions essential for safe flight.