Summary
This document proposes the adoption of a new airworthiness directive (AD) that is applicable to certain Saab Model SAAB SF340A, SAAB 340B, and SAAB 2000 series airplanes. This proposal would require replacement of the hubcap drive coupling of the main wheel with an improved coupling. This proposal is prompted by reports of unexpected decreases in the pressure of the main wheel brake due to incorrect engagement between the main wheel coupling and the wheel speed transducer, which can result in false signals being sent to the anti- skid control box. The actions specified by the proposed AD are intended to prevent loss of brake effectiveness due to a decrease in the pressure of the main wheel brake.