Airworthiness Directives; Saab Model SAAB SF340A and SAAB 340B Series Airplanes

The FAA is adopting a new airworthiness directive (AD) for all Saab Model SAAB SF340A and SAAB 340B series airplanes. This AD requires a one-time inspection to determine the part and serial numbers of certain engine vibration isolators (mounts) and the cure dates of certain molded assemblies incorporated in those engine mounts; and related corrective actions if necessary. This AD is prompted by a report that disbonding of the elastomer from the inner metal core and shim of certain engine vibration mounts has occurred within a few hundred hours of operation, causing heavy chafing of the engine support system and chafing of the fire sensor loop. We are issuing this AD to prevent reduced integrity of the fire-shielding capacity of the nacelle structure and a possible fire detector fault.