TM 1-1520-238-T-7
11–61
11–7.
SYSTEM DESCRIPTION (cont)
11–7
(k) Roll SCAS (fig. 11–34) is a combination of SAS and CAS. Roll SCAS controls the helicopter’s roll
axis as a function of rate, attitude and cyclic stick position. When the roll engage switch on the pilot ASE panel is
placed in the ROLL position, the DASEC latches the switch and engages roll SCAS. The DASEC disengages roll
SCAS under the following conditions: if HARS malfunctions, the SAS servocylinder LVDT feedback does not
match the DASEC mathematical model, a mistrack between the pilot’s and CPG’s LVDTs occurs, a mistrack
between dual position 1 (BUCS 1) LVDT and the pilot’s LVDT occurs, or a mistrack between dual position 1
(BUCS 1) and dual position (BUCS 2) occurs. Disengagement lights the ASE indicators on the pilot and CPG
caution/warning panels.
HARS
ROLL SYNCHRO
PILOT LVDT INPUT
DASEC
SAS LVDT FEEDBACK
SAS SOLENOID
COMMAND
LVDT FEEDBACK
LATERAL
SERVO
MAIN
ROTOR
ASE
CAUTION/WARNING
PANEL
M70-272
ROLL
MONITOR
28 VDC
PILOT
ASE
PANEL
Figure 11–34.
SAS/CAS Roll Functional Block Diagram
(l) Yaw SCAS (fig. 11–35) is a combination of SAS and CAS. Yaw SCAS controls the helicopter’s
vertical axis as a function of rate, attitude and directional pedal position. When the yaw engage switch on the pilot
ASE panel is placed in the YAW position, the DASEC latches the switch and engages yaw SCAS. The DASEC
disengages yaw SCAS under the following conditions: if the ADSS malfunctions, the SAS servocylinder LVDT
feedback does not match the DASEC mathematical model, a mistrack between the pilot’s and CPG’s LVDT
occurs, a mistrack between dual position 1 (BUCS 1) LVDT and the pilot’s LVDT occurs, or a mistrack between
dual position 1 (BUCS 1) and dual position 2 (BUCS 2) occurs. Disengagement lights the ASE indicators on the
pilot and CPG caution/warning panels. The squat switch automatically disengages yaw CAS when the helicopter
is on the ground. SAS, however, operates normally if engaged.
