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A 737-300/400/500MAINTENANCE MANUAL
3. System Interface (Figs. 2 and 3)
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A. Flight Management Computer (FMC)
(1)
The FMC performs the computational, logical, and input/output navigation processing required by the guidance flight planning and performance function. The outputs of the FMC are in ARINC 429 digital format.
(2)
Power for the computer is provided by a power supply unit. The unit is a subassembly of the computer chassis. The power supply is designed for 115-volts, 400-Hz, single phase input power.
(3)
The FMC is packaged in accordance with ARINC 600. The basic chassis is composed of aluminum extrusions and plates, mainly secured by epoxy, to form a homogeneous box with two open sides. One side of the FMC is closed by use of a cover attached with quick-disconnect fasteners. The power supply assembly forms the other side cover and is held in place by captive machine screws. There is no internal fan, as the FMC receives its cooling air from the airplane air-conditioning system. The cover and power supply must be fastened in place for proper unit cooling.
B. Control Display Unit (CDU)
(1)
The CDU includes a display and keyboard that allows the operator to interface with the FMC. The CDU displays airplane initialization, reference, flight planning, and performance data. The CDU keyboard enables the operator to enter parameter values to support processing of flight management functions.
(2)
The CDU also provides a means of initiating, controlling, and displaying the operation and status of BITE, for the flight management system.
(3)
The CDU assembly contains the following components: a keyboard lightplate assembly, chassis, high and low voltage power supplies, circuit cards, and a Cathode Ray Tube (CRT).
(4)
The front panel on the CDU contains the keyboard switches with integral lighting. The CDU keys are shaped to help set apart their respective functions. The numeric keys are circular in shape, while the alphabetical keys are square. The line select and function keys are rectangular in form.
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A
737-300/400/500MAINTENANCE MANUAL
(5)
The CDU chassis contains the high and low voltage power supplies. The chassis consists of multiple plates that form a rigid EMI-tight enclosure.
(6)
The CRT subassembly contains a five-inch cathode ray tube, yoke, high contrast filter, and an EMI shield. The cathode ray tube is flat faced; a glass optical filter is bonded to the front of the tube.
C. Digital - Analog Adapter (DAA)
(1) Sensors with analog outputs, and displays with analog inputs, must be able to communicate with the digital FMC. Conversion of analog signals to digital signals, and vice versa, is accomplished by the DAA.
D. Distance Measuring Equipment (DME)
(1)
The DME interrogators provide distance information to the FMC, through the DAA. When manual tuning is selected on the VHF navigation control panel, a manually selected DME frequency is tuned. If automatic tuning is selected the DME interrogators are tuned by signals from the FMC.
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本文链接地址：737-300 400 500 AMM 飞机维护手册 导航 NAVIGATION 4(74)
