ULLETIN MOS MSC SB 49-7431 APU - REWORK UPPER AND LOWER INLET PLENUM TO EUMINATE RIVETED GROUND STRAPS. SERVICE BULLETIN SB 49-7476 MOS MSC APU - REWORK TURBINE BEARING SUPPORT AND REAR BEARING SEAL RETAINER FOR SOFT HYDRAULIC MOUNT. SB 49-7480 SERVICE BULLETIN MOS MSC APU - REWORK OR REPLACE DRIVEN COMPRESSOR BEARING HOUSING AND COUPLING SHAFT FOR