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757
MAINTENANCE MANUAL
(8) AIRPLANES WITH CONTROL WHEEL STEERING; Roll Control Wheel Steering (Fig. 11A)
(a)
The MCP controls associated with the control wheel steering (CWS) mode are shown on Fig. 11A.
(b)
The CWS mode is requested by pressing the CWS ENGAGE switch/light (L, C, or R). After engage conditions are verified, CWS engage logic is generated and detent engage discretes are applied to the A/P servos. The pilot controls the airplane in CWS mode to follow F/D commands.
(c)
When either F/D switch is ON, the EADI displays are enabled for all permissible F/D modes (LNAV, HDG SEL, B/CRS, LOC, and APP). Heading hold cannot be manually selected in CWS but can be automatically acquired as a CWS submode.
(d)
Roll signal synchronization takes place before the A/P is engaged. After CWS engage is achieved, three CWS submodes are possible without MCP action: CWS maneuver, CWS attitude hold, and CWS heading hold.
(e)
During the CWS maneuver submode, the pilot controls roll attitude by control wheel force. The CWS attitude hold submode is selected when wheel force is less than 2 pounds. The heading hold submode is selected when heading capture criteria are satisfied. The aircraft rolls to wings level and then maintains heading hold.
(f)
CWS Initial Engage and Roll Down to Wings Level (Situation A)
1) If CWS ENG occurs when the bank angle is below heading capture criteria, the control wheel follows the wings level command. The AFDS status FMA displays FD CWS and the F/D displays roll commands for wings level. The ADI display is independent of CWS control laws and is controlled by mode logic.
(g)
CWS Heading Hold (Situation B)
1) The CWS HDG HLD submode holds the current adjusted heading at the time heading capture criteria are satisfied. The AFDS status FMA displays FD CWS. The F/D displays roll commands for heading hold. The HDG HLD submode continues until the CWS maneuver submode is enabled.
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757
MAINTENANCE MANUAL
OFF ON F/D OFF SPD EPR A/T ARM IAS/MACH SEL FL CH V NAV AUTO 5 L NAV HDG SEL HOLD 25 LIMIT BANK VERT SPD DN UP V/S HOLD ALT B/CRS LOC APP L CWS CMD C CWS CMD DISENGAGE A/P ENGAGE CWS CMD R OFF ON F/D
FIRST
CAPTAIN'S CWS ENGAGE
OFFICER'S
F/D SWITCH SWITCH/LIGHTS
F/D SWITCH
ABC D
Roll Control Wheel Steering
Figure 11A
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WHEEL STEERING ú ú 24 Page 29 ú Jan 20/98
BOEING PROPRIETARY - Copyright (C) - Unpublished Work - See title page for details.
A
757
MAINTENANCE MANUAL
(h)
CWS Maneuver (Situation C)
1) The CWS maneuver submode is enabled by applying more than 2 pounds force to the control wheel. It establishes a roll rate proportional to control wheel force. Flight control cable feedback drives the control wheel to follow manual force input. The AFDS status FMA displays FD CWS, HDG HOLD. The F/D displays roll commands for returning to wings level. This submode ends when control wheel force is less than 2 pounds.
(i)
CWS Roll Attitude Hold (Situation D)
1) The CWS roll attitude hold submode holds the established bank angle between 5 and 30 degrees. The AFDS FMA displays FD CWS, ATT. The F/D displays roll commands for return to wings level. This submode continues until the CWS maneuver submode is enabled to change the bank.
(9) AIRPLANES WITH CONTROL WHEEL STEERING; Roll CWS Engage Logic
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