APU - AIRBORNE AUXILIARY POWER - GAS TURBINE ENGINE - REPLACE FIRST STAGE TURBINE ASSEMBLY. PN RECOMMENDED 3840160-5. -7. -8 OR PN 3840303-1. AND STATIONARY SEAL ASSEMBLY. PN 3844738-5. WITH FIRST STAGE TURBINE ASSEMBLY. PN 3840310-3 AND STATIONARY SEAL ASSEMBLY. PN 3844738-6. SERVICE BULLETIN MOS MSC SB 49-7988