TM 1-1520-238-T-7
11–60
11–7.
SYSTEM DESCRIPTION (cont)
11–7
(i) Pilot and CPG LVDT (fig. 11–32) positions are compared by a level detector. If the level detector
detects a difference of position of 40% (mistrack), the DASEC commands disengagement of that axis. This
action lights the ASE indicators on the pilot and CPG caution/warning panels.
DASEC
PILOT
LVDT
CPG
LVDT
DEMODULATOR
DEMODULATOR
M
U
X
SOFTWARE
TRIP LEVEL
+ 30% IN
ALL AXES
LEVEL
DETECTOR
DISENGAGE
COMMAND
(LOGIC ZERO)
M70-270
Figure 11–32.
Position LVDT Monitor Functional Block Diagram
(j) The pitch stability command augmentation system (SCAS) (fig. 11–33) is a combination of SAS and
CAS. Pitch SCAS controls the helicopter’s pitch axis as a function of rate, attitude and cyclic stick position. When
the pitch engage switch on the pilot ASE panel is placed in the PITCH position, the DASEC latches the switch and
engages pitch SCAS. The DASEC disengages pitch SCAS under the following conditions: if HARS or ADSS
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 2 (BUCS 2) occurs.
Disengagement lights the ASE indicators on the pilot and CPG caution/warning panels.
ADSS
AIRSPEED
HARS
PITCH SYNCHRO
PILOT LVDT INPUT
DASEC
SAS LVDT FEEDBACK
SAS SOLENOID
COMMAND
LVDT FEEDBACK
LONGITUDINAL
SERVO
MAIN
ROTOR
ASE
CAUTION/WARNING
PANEL
M70-269
PITCH
MONITOR
28 VDC
PILOT
ASE
PANEL
Figure 11–33.
SAS/CAS Pitch Functional Block Diagram
