22-11-00
ú ú 13 Page 40 ú Nov 12/01
BOEING PROPRIETARY - Copyright (C) - Unpublished Work - See title page for details.
A
737-300/400/500MAINTENANCE MANUAL
B. Engage Interlock Interface Operation (Fig. 14)
(1) The DFCS engage interlock information is obtained from many interfacing systems and switching signals. This schematic shows the engage interface and function of the following signals:
(a)
The auto speed brake module is used to sense a main wheel spin of greater than 60 knots.
(b)
The A/P disengage switches are in series. Pressing either switch disengages the A/P.
(c)
The air ground relay is used to sense the on ground condition (SQUAT). A closed switch indicates on ground.
(d)
The hydraulic pressure switches are used to sense when the A/P actuators are fully activated (DETENT). A closed switch indicates hydraulic pressure.
(e)
Two Radio ALT (LRRA) discretes are used for validity, one input is used when on dual engage and the other for single channel operation. A foreign radio altitude is transmitted to the other FCC on the X channel data bus.
(f)
The VHF NAV unit provides discretes for ILS DC (LOC frequency selected), VHF/LOC valid and G/S valid.
(g)
Transfer relays provide discretes to indicate the normal position of that system.
(h)
TO/GA switches are used to activate the takeoff or GA mode and provide engage interlock information.
(i)
The landing gear lever is used to sense gear position. A open switch indicates landing gear up.
(j)
The XFR control senses an AC bus XFR. The closed position indicates the normal position.
(k)
The aileron force limiter is monitored to assure that the limiter is in the correct position for the flap setting. Switched contacts ensure that the clutch solenoid is not energized prior to A/P engage and energized after the A/P is engaged. The AFC accessory unit provides a diode network so that if either FCC is engaged in CWS or CMD the aileron force limiter clutch is engaged.
(l)
The aileron force limiter sets the authority limits for the A/P. The limit is set at 17 degrees with flaps up and 25 degrees with flaps not up. Flap switch S245 controls a relay in the accessory unit which controls the ac power to a motor in the aileron force limiter. An auxiliary contact of the motor limit switch is connected in series with flap switch S290 to ensure valid authority limit.
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22-11-00
ú ú 11 Page 41 ú Nov 12/01
BOEING PROPRIETARY - Copyright (C) - Unpublished Work - See title page for details.
A737-300/400/500MAINTENANCE MANUAL
EFFECTIVITYùùùùùùùùùùùùùùùùùùùùùùùùùùùùùù.AIRPLANES WITHOUT EFIS ú
22-11-00
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