.  
Check the SAC's ability to correctly read gross weight data from FMC's ARINC 429 data bus.

.  
Check the SAC's hardware that turns on the "Speedbrake Do Not Arm" light.

.  
Check ADC data bus inputs.

. 
 Flaps inputs

.  
Air ground logic

See Part II of this supplement for maintenance procedures.
Aviation Partners Boeing
757-200
MAINTENANCE MANUAL SUPPLEMENT
 Part I

Figure 1
CONTROL STAND

Figure 2
Control Stand Looking Down
(Speedbrake Lever Location)

Aviation Partners Boeing
757-200
MAINTENANCE MANUAL SUPPLEMENT
 Part I

Figure 3
Speedbrake Handle Forces

Aviation Partners Boeing
757-200
MAINTENANCE MANUAL SUPPLEMENT
 Part I

Figure 4 
Wiring Configuration – In Air with Flaps Up 
 AP57.2-0600-2  27-62-00 
Page 12 
Jan 07 

Aviation Partners Boeing
757-200
MAINTENANCE MANUAL SUPPLEMENT
 Part I

M10332
M10331

K149
K145

Figure 5
SAC Block Diagram 

Aviation Partners Boeing
757-200
MAINTENANCE MANUAL SUPPLEMENT
 Part I

7

THE MINIMUM SPEED FOR FLAPS 1 IS 200 KNOTS.
S=set  R=reset
INPUT SIGNAL DEFAULTS
Parameter  SAC Default for Autostow Function if Valid Signal is Not Received 
Calibrated Airspeed  300 knots 
Airplane Gross Weight  260,000 pounds 
T.E. Flap Position  Flaps Up 
In Air Logic  In Air 

Figure 6 Speedbrake Autostow Function’s Control Law
Aviation Partners Boeing
757-200
MAINTENANCE MANUAL SUPPLEMENT
 Part I

TURN ON
“AUTO SPDBRK”
LIGHT

AIRPLANE GROSS WEIGHT
GREATER THAN 221,000 LBS

AIRPLANE GROSS WEIGHT
LESS THAN 222,000 LBS

AIRPLANE GROSS WEIGHT
GREATER THAN 221,000 LBS

AIRPLANE GROSS WEIGHT
GREATER THAN 220,000 LBS

S=set  R=reset
NOTE: Invalid Gross Weight Data Does not turn on “Speedbrake Do Not Arm” Light because the default gross weight value is 260,000 pounds, so Autostow is available.
Figure 7
“Speedbrake Do Not Arm” Light Logic for Autostow Function

Aviation Partners Boeing
757-200
MAINTENANCE MANUAL SUPPLEMENT
 Part I

Up
Floor Beam
Support Fitting Control Rod (Existing)
Lever (Existing)
Stowed
Speedbrake Handle
Noback Mechanism
To Auto Speedbrake System, including actuator and LVDTS
Control Rod
Autostow Actuator
Spring Adjustment Lug
　
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