Airworthiness Directives; Boeing Model 737-300 and -400 Series Airplanes

We are adopting a new airworthiness directive (AD) for certain Boeing Model 737-300 and -400 series airplanes. This AD requires testing and inspecting a certain web panel of the main wheel well pressure deck to determine the material type and thickness; and related investigative and corrective actions if necessary. This AD results from several reports indicating that cracks ranging from 0.8 to 8.0 inches long were found on a certain web panel of the main wheel well pressure deck. We are issuing this AD to prevent fatigue cracking in the web panel of the main wheel well pressure deck, which could result in venting and consequent decompression of the airplane.