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ALL ú ú 01F Page 501 ú Oct 10/93
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747-400 MAINTENANCE MANUAL
AUTOTHROTTLE SYSTEM - DESCRIPTION AND OPERATION
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General
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A. The Autothrottle (A/T) System computation is performed by the Thrust Management Function (TMF) of the Flight Management Computer (FMC). A description of the autothrottle is therefore covered in the thrust management portion of the FMCS (Ref 34-61-00/001).
B. The autothrottle system components are located in the control stand. The autothrottle system consists of the brake shaft assembly, the autothrottle servomotor generator and gearbox, and the autothrottle disconnect, reset, and go-around switches. To replace these components, engine control components must be removed. Therefore, the autothrottle components are included in ATA chapter 76, Engine Controls, to provide a complete set of procedures in one chapter. Refer to 76-12-00/001 for a complete Autothrottle System Description and Operation.
C. The Central Maintenance Computer System (CMCS) (AMM 45-10-00/001) monitors the FMCS for autothrottle related faults or failures and is accessed through the Control Display Unit (CDU). The CDU acts as the focal control and display for initiating and interacting with BITE and for identifying faults in systems monitored by the CMCS.
D. Faults or failures monitored by the CMCS appear as maintenance messages on the CDU. Autothrottle faults or failures will appear, therefore, on the CDU in maintenance messages identified by ATA Chapter 34-61, Flight Management (Ref 34 - CMCS MESSAGE INDEX).
Brake Shaft Assembly
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A. AMM 76-11-05/401, Removal/InstallationAutothrottle System
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A. Description and Operation, Ref 76-12-00/001
B. Thrust Management, Ref 34-61-00/001Autothrottle Servomotor Generator and Gearbox
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A. Removal/Installation, Ref 76-12-01/401
B. FMCS Operational Test, Ref 34-61-00/501Autothrottle Disconnect and Go-Around Switches
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A. Removal/Installation, Ref 76-12-02/401
B. Adjustment/Test, Ref 76-12-02/501
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747-400
MAINTENANCE MANUAL
6. Testing FMCS using BITE
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A. Testing of the autothrottle system is covered in the thrust management portion of the FMCS Adjustment/Test (Ref 34-61-00/501).
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