Summary
The FAA proposes to adopt a new airworthiness directive (AD) for all Saab Model SAAB SF340A and SAAB 340B series airplanes. This proposed AD would require a one-time inspection to determine the part and serial numbers of certain molded assembly engine mounts (isolators) and the cure dates of certain bonded canister assemblies incorporated in those engine mounts; and related corrective actions if necessary. This proposed AD is prompted by a report that disbonding of the elastomer from the inner metal core and shim of certain molded assembly engine 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 proposing this AD to prevent reduced integrity of the fire-shielding capacity of the nacelle structure and a possible fire detector fault.