UP LIMITUP LIMIT UP LIMIT FLAPSSWITCH 1 FLAPS SWITCH 1 FLAPS SWITCH 1 RETRACTEDRETRACTEDRETRACTED UP LIMITUP LIMITUP LIMIT FLAPS NOTFLAPS NOT SWITCH 2FLAPS NOT SWITCH 2SWITCH 2 RETRACTEDRETRACTEDRETRACTED
SWITCH 3 D0WN LIMIT SWITCH 3 D0WN LIMIT SWITCH 3 DOWN LIMIT
GREEN GREEN GREEN
SWITCH 4 SWITCH 4 SWITCH 4BAND BAND BAND
UP LIMIT UP LIMIT UP LIMIT
SWITCH 5 STANDBY SWITCH 5 STANDBY SWITCH 5 STANDBY
TRIM TRIM TRIM
DOWN LIMIT DOWN LIMIT DOWN LIMIT
SWITCH 6 STANDBY SWITCH 6 STANDBY SWITCH 6 STANDBY
TRIM TRIM TRIM
RVDT SPM (C) RVDTSPM (L) RVDT SPM (R)
NOT F/O'SCAPTAIN'S
SYNCHRO SYNCHRO SYNCHRO INDICATORINDICATOR USED
ELECTRICAL ELECTRICAL ELECTRICAL
CONNECTOR CONNECTOR CONNECTOR
LSTM FUNCTIONS
A-A
Stabilizer Trim Limit Switch and Position Transmitter Modules
Figure 2 (Sheet 2)
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27-48-00
SWITCHES ON THE CONTROL STAND ú ú 02 Page 5 ú Jun 20/93
BOEING PROPRIETARY - Copyright (C) - Unpublished Work - See title page for details.
A
757
MAINTENANCE MANUAL
(4)
The travel limit switches are only functional on the left and right LSTM's. They interrupt the trim signal from the SAM's to the Stabilizer Trim Control Modules (STCM's) at the stabilizer up and down travel limits (AMM 27-41-00).
(5)
The up and down travel limit switches for normal operation are only functional on the left and right LSTM's. The up and down limit switches for standby trim are only functional on the left and right LSTM. They interrupt the trim signal from the SAM's to the Stabilizer Trim Control Modules (STCM's) at the stabilizer up and down travel limits (AMM 27-41-00).
(6)
The greenband switch is only functional on the center LSTM. The switch signals the takeoff configuration card to issue a takeoff configuration warning and annunciation if the stabilizer trim position is outside of the greenband range and the airplane is in a takeoff configuration.
C.
Stabilizer Position Modules (SPM's)(Fig. 3)
(1)
Each of the SPM's recieve a stabilizer trim position input signal from the corresponding LSTM.
(2)
The left and right SPM's signal stabilizer trim position to the SAM's.
(3)
All SPM's signal stabilizer trim position to the AFDS.
(4)
The SPM's are located in the electrical system card file P50.
3. Operation
_________
A. Functional Description (Fig. 4)
(1)
The stabilizer trim position indicating system provides position information to the flight crew as well as other systems.
(2)
Stabilizer trim position is sensed by three LSTM's, each driven by a mechanical cable system.
(3)
Stabilizer trim position is displayed by indicators on the control stand. When the stabilizer trim setting is outside of the takeoff greenband, the takeoff aural warning circuit is armed. If the indicator loses power, an "OFF" flag will appear at the bottom of the indicator. If there is a loss of the synchro signal to the indicator, the indicating tape will disappear from view.
(4)
Each SPM contains a BITE with troubleshooting lights. A single green light indicates that SPM components are operative . Two amber lights indicate inoperative components.
B.
Control
(1)
The system is on whenever the following overhead panel P11 circuit breakers are closed:
(a)
11F19, STAB POS MOD C
(b)
11G15, STAB POS MOD L
(c)
11G24, STAB POS MOD R
(d)
11H10, STAB TRIM POS IND L
(e)
11H19, STAB TRIM POS IND R
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