red.
3) A two-tone siren sounds
(b)
Two WARN outputs are generated for each of these warning functions. One WARN output uses software logic and is inhibited by a loss of normal power or a computer failure. The second WARN output uses hardware logic that is powered by 28 vac standby power. This ensures a valid warning if normal power is lost.
(c)
Signal Generation
1) Latches are set when the FCC is engaged in CMD or the servos are armed. If the FCC subsequently disengages, an A/P WARN 1 and A/P WARN 2 signal is issued if no other FCC is engaged. All outputs are generated anytime either autopilot disengage switch is operated.
(d)
Reset
1) When the autopilot is disengaged with the A/P disengage switch, pressing the switch again resets the disengage warnings. Reset of an autopilot disengage warning due to any other means of disconnect is achieved by pressing the control wheel disengage switch once.
D. Autopilot/Flight Director System Signal Source Fault Detection (SSFD) (Fig. 9)
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22-14-00
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A
747-400
MAINTENANCE MANUAL
ENABLE2EQUALIZATION
MID PITCH &
ROLLLOCAL DATALOCAL DATA VALUESELECTED DATA
INPUT
SELECTORMODE7
MONITOR
LOGIC ENABLE
A LOCAL FAILENABLE
FAULT
DETECTION
LOCAL COMPUTATION (SSFD)
L DATACROSS
SAME AS LOCAL L DATA
LOCAL FAIL
CHANNEL
FAIL
MONITOR
L COMPUTATION (SSFD)L FAIL
ANY FAIL SELECTED
LOGIC
PARAMETERFAILARM/
R DATA TWO FAIL
SAME AS LOCAL R DATA
ENGAGE
INPUTLOGIC
SELECT
R COMPUTATION (SSFD) R FAIL
FAILLOCAL SIGN STATUSSELECT
MATRIX VALID
LOCAL PARAMETER
INPUT
NORMAL
1ACTIVITYSSM
SELECT LOGIC
TWO SSM VALID
GS í 60 KTS
FAIL
L SSM VALID
SQ 1 F/D ON
SELECT L PARAMETER ACTIVITYCMD ENGA
SOFTWAREL X-CHANNEL VALID
HARDWARER SSM VALID
IRS, SURF
R PARAMETERR POS, RWY
LOCAL FAIL
ACTIVITY 1FOR THE FOLLOWING
HDG VOTE
FAIL
R X-CHANNEL VALID
PARAMETERS:LOCAL STAB. POS VALIDANY FAIL
GS . 40 KTS
LOGIC PITCH ANGLE, PITCH RATE,
LOGIC TWO FAIL
L STAB. POS VALID
ROLL ANGLE, ROLL RATE,L X-CHANNEL VALID
ONE SSM VALID
MAG HDG, YAW RATE, TRUER STAB. POS VALID
HDG, GND SPD, TRUE TRACK
SIGN STATUS LOC SELANGLE, MAG TRACK ANGLE,
R X-CHANNEL VALID MATRIX (SSM) VERT ACCEL, LATERAL
APP SELB 2 ACCEL, NORM ACCEL, CROSSTK ACCEL, ALONG TK ACCEL,
INPUT
SELECTFLT PATH ACCEL, SEL RWY
PITCH
3SQ
MODEHDG, STAB. POS, FLAPLOGIC G/S ACTIVE 4
2
POS, AIL SURF POS, ELEVFAIL
SURF POS, RUD SURF POSRA . 1500'
ONE SSM VALID
5
SELECT ILS FREQ CHANGE 6 2RADIO SIGNALS: G/S DEV,
R
LOC DEV, RADIO HEIGHT
GO AROUND SEL
ARM/
6
RA í 400'
SELECTED
ENGAGE
3 LOC DEV
LOGIC
DATA
A
4G/S DEVSQ
5RADIO HEIGHTROLLRADIO
6LOC DEV & G/S DEVMODE LOC ACTIVE
SIGNALS
LOGIC
B
R
7 FOR ATTITUDE RATE AND
VOTEACCELERATION SIGNALS,
GND IS USED, NOT
SELECTED DATAFLIGHT CONTROL COMPUTER LOGIC
AFDS Signal Source Fault Detection (SSFD) Schematic
Figure 9
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