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MAINTENANCE MANUAL
J. Sensors
(1)
Critical sensors are those which provide raw data inputs during Autoland. Each FCC receives a dedicated input from a critical sensor. Autoland critical sensors are the Instrument Landing System (ILS) receiver, Inertial Reference Unit (IRU), Radio Altimeter (RA), and the Electrical Power (Control) System (EPCS).
(2)
Non-critical sensors are those which do not provide essential raw data during Autoland. The FCCs receive non-critical sensor inputs through instrument switching or common data links. Non-critical sensors are the Flight Management Computer System (FMCS), Air Data Computing System (ADCS), Proximity Switch Electronic Unit (PSEU), and the flap and slat position sensors.
K. AFDS Outputs
(1)
The AFDS produces the following outputs:
(a)
Autopilot servo commands
(b)
Flight director displays
(c)
Mode status and Autoland annunciation
(d)
Caution and Warning outputs
(e)
Flight data acquisition signals
(2)
Interchannel data permits data sharing and total system verification during Autoland (Ref 22-15-00).
(3)
Each FCC provides analog servo commands to its own Electrohydraulic Servo Valves. Each FCC also provides analog discretes to the other two FCCs when its pitch and roll A/P servos are engaged.
(4)
Output buses one, two, and three from each FCC, supply the MCP, MCDP, and EFIS symbol generators respectively.
(5)
GUN 051, 104-999; output bus four from each FCC supplies the Digital Flight Data Acquisition Unit (DFDAU) (Ref 31-31-00).
(6)
FCC - Analog Discrete Outputs
(a)
GUN 051; pin G11, of each FCC, supplies 28 vdc (engage hold) to its own ENGAGE lever (switch) in the MCP.
(b)
Pin A6 supplies a ground to the electrical power (control) System when the AUTOLAND BUS ISOLATE REQUEST discrete is produced after triple channel APP selection (Ref 24-22-00).
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(c)
Pin F9 normally supplies 28 vdc, but changes to ground if the FCC detects any detent trip condition. The signal is fed to the other two FCCs.
(d)
Pin G10 supplies 28 vdc to the other two FCCs when A/P servos are engaged. A ground is supplied when they are disengaged.
(e)
Pin K2 supplies an A/P CAUTION - 1 ground which illuminates the AUTOPILOT amber caution light on the P1-3 panel.
(f)
Pin K3 supplies an A/P CAUTION - 2 ground to the Engine Indication and Crew Alerting computer (Ref 31-41-00).
(g)
Pin E12 (A/P WARN 2 - BAT) and pin E12 (A/P WARN 2) both supply grounds in the A/P WARN condition to two independent inputs of the aural warning module in the WEU (Ref 31-51-00).
(h)
Pin G12 (A/P WARN 1 - BAT) and pin G12 (A/P WARN 1) both supply grounds in the A/P WARN condition to two pairs of bulbs in the red A/P DISC warning light on the P1-3 panel.
L. AFDS Inputs
(1)
Each FCC has analog inputs as shown from its own autopilot lateral control servo, autopilot pitch control servo, autopilot rollout guidance servo, and from the respective (L, C, and R) flap and stabilizer position modules.
(2)
FCC Digital Inputs and Cross Channel Lines.
(a)
Cross-channel data is encoded in vendor unique code; all other data is transmitted in standard ARINC 429 format. Critical sensor data is transmitted on dedicated data links while non-critical data is stored or switched.
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