(b)  
There will be no response to any of the MCP pushbuttons with both F/D switches OFF and either A/P ENGAGE paddle in the CWS position.

(c)  
Pushbutton mode selection is push on and push off for all flight director modes with either/or both F/D ON.

(d)  
The selection of another mode in the same axis cancels the existing mode, i.e. with V/S engaged, selection of ALT HOLD engages ALT HOLD and cancels V/S. The exceptions to this are ALT HOLD and autopilot approach modes.

(e)  
All autopilot cruise modes are push on push off with exception of ALT HOLD.

(f)  
Placing an A/P ENGAGE switch to CMD while in an existing flight director mode, will cancel the mode and provide CWS if the Performance Assessment Monitor (PAM) threshold is exceeded. The system will remain in CMD and engage the mode if PAM is within limits.

(g)  
With either A/P ENGAGE switch in CMD and with no mode selected, CWS is provided.

(h)  
With either A/P ENGAGE switch in CWS or CMD the other switch may be raised to CWS or CMD. The previously engaged switch will drop to OFF and any existing mode will remain engaged if the PAM is within limits. Excessive PAM threshold will disconnect the mode.

505 
Oct 20/84  BOEING PROPRIETARY - Copyright . - Unpublished Work - See title page for details.  22-11-01 Page 16C/16D 

B.  Autopilot Engage (Fig. 7)
(1)  
The autopilot engage switch is a three position device which requires operating voltages to permit switch movement from OFF position and correct holding voltages to latch the switch in CWS of CMD, whichever is selected. The engage solenoid must be energized by voltage through various mode positions and solenoid ground is supplied by AFCS valid logic.

(2)  
The engage switch OFF interlock voltage originates from the interlock circuit breaker and is routed through disconnect switches, energized disconnect relay, energized - de-energized combination of A or B UP engage relays, through disengaged roll and pitch bypass relays to the engage switch in the AFCS control panel. The AFCS VALID (sheet 2) must remain at a low (ground) to energize the engage solenoid. The multiple input valids combine and invert as required to maintain a low on the output OR logic when interlocks and valids are correct.

(3)  
The CWS mode engage interlock is very similar to OFF mode requirements. When the engage switch is moved from OFF to CWS, A or B engaged relays controlled by the engaged force limiter change state to provide the required voltage. The AFCS valid must remain low (ground) to hold the engage paddle in the CWS position.

(4)  
The CMD mode engagement interlock is identical to CWS mode for the voltage side of the engage solenoid. The AFCS valid low (ground) requires additional logic due to mode selection capability in CMD mode.

(5)  
The remaining contacts of the engage switch are shown on sheet 3. These switches are used to provide pitch and roll actuator engage, force limiter engage, cross channel engage logic and warning circuit enable. Additional cross channel logic is also shown.

580 
Oct 20/83  BOEING PROPRIETARY - Copyright . - Unpublished Work - See title page for details.  22-11-01 Page 17 

C.  Flight Director Control
(1)  The flight directors are controlled by toggle switches on the mode control panel. The switch on the captains side of the panel controls A flight director and the switch on the F/O side of the panel controls B flight director. The switches have an ON and an OFF position with no holding feature. The flight director switch discrete is transmitted to the FCC via digital data format. Mode annunciation is made on the common AP/FD Flight Mode Annunciator (FMA) panel. The A FCC flight director commands are displayed on the Captain's ADI and the B FCC flight director commands are displayed on the First Officer's ADI.
(a)  
The CAPT ADI bars are always driven from the A FCC only and the F/O ADI bars are always driven from the B FCC only.

(b)  
In all flight modes and regardless of AP operational status, each ADI display is activated when the respective F/D switch is moved to ON (and all valids are true and a mode is selected).

(c)  
In all modes, and where one or both APs are in CMD, both FMAs are effectively driven from the AP (or 1st AP) in CMD regardless of F/D status. The FMAs will always annunciate AP mode.

(d)  
When the AP is in CWS or OFF, and both F/Ds are ON, the Captain's FMA is driven from the A FCC and the First Officer's FMA is driven from the B FCC when in APProach. In all other modes, both FMAs are effectively driven from the 1st F/D ON.

(e)  
Under all conditions except three (the independent conditions), the mode logic for the two flight directors is slaved with the 1st F/D ON getting the Master status (AP OFF or CWS). This status is indicated by illuminating the Master F/D light located on the MCP by the F/D ON/OFF switch. This light removes the ambiguity about which F/D is displaying the proper commands when the two NAV receivers are tuned to different stations. In any of the following three conditions, the F/Ds are independent and unslaved and both Master lights are illuminated. The independent conditions are APProach after G/S engaged and LOC engaged, G/A below 400 ft of radio altitude, and T/O below 400 ft. 
　
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