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CHAPTER 6 HEADING ATTITUDE REFERENCE SYSTEM (HARS) MULTIPLEX READ CODES | Up
TM-1-1520-238-T-3 Army Model AH-64 Helicopter (NSN
1520-01-106-9519) (EIC: RHA) Multiplex Read Codes Manual | Next
HARS INTERNAL TEST REPLY (ACY) HARS TEST PERF (ACZ) |
TM 1–1520–238–T–3
6–2
Change 7
MULTIPLEX READ CODE INTERPRETATIONS
6–1 SIGNAL NAME:
HARS MISSION DATA MEMORY
MEMORY LOCATION: 002204
MEMORY DATA BIT(S):
4–19(ACY)4–15(ACY)(SCALAR)
CONDITION:
Access read code after HARS has been energized at least 90 Seconds.
SIGNAL FUNCTION:
HARS mission data memory.
REMARKS: From HARS through DASEC to FCC.
PASS:
If code reads 000000, mission data memory is clear, go to paragraph 6–1.1.
FAIL: If one or more digit(s) reads 7, mission data memory is saturated, go to
TM 11–1520–238–23–2, to clear memory.
6–1.1 SIGNAL NAME:
HARS MODE
MEMORY LOCATION: 002154
MEMORY DATA BIT(S):
6, 7
(BINARY)
CONDITION:
If fifth digit displayed on heads out display (HOD) is 0 or 4=NORM
If fifth digit displayed on HOD is 1 or 5=FAST
If fifth digit displayed on HOD is 2 or 6=INFLT (not used)
If fifth digit displayed on HOD is 3 or 7=OPR
SIGNAL FUNCTION:
Monitors HARS mode switch.
REMARKS: From heading and attitude reference system (HARS) through digital automatic
stabilization equipment computer (DASEC) to fire control computer (FCC).
PASS:
If CONDITION corresponds to selected switch mode, go to paragraph 6–2.
FAIL: Location of fault: HARS, HARS panel, wiring from HARS panel to DASEC, DASEC.
Troubleshoot wiring to isolate fault (TM 11–1520–238–23–2).
6–2 SIGNAL NAME:
HARS SQUAT SWITCH
MEMORY LOCATION: 002235
MEMORY DATA BIT(S):
19
(BINARY)
CONDITION:
(None)
SIGNAL FUNCTION:
Squat switch indicates aircraft is on ground to HARS.
REMARKS: From FCC through DASEC to HARS.
PASS:
If first digit on HOD is 0, 2, 4, or 6, go to paragraph 6–3.
FAIL: Location of fault: squat switch, squat switch relay. Troubleshoot wiring to isolate fault
(TM 1–1520–238–T–6).
6–3 SIGNAL NAME:
HARS INT TEST CMD (ACY) HARS INTLTEST CMD (ACZ)
MEMORY LOCATION: 002235
MEMORY DATA BIT(S):
18
(BINARY)
CONDITION:
(None)
SIGNAL FUNCTION:
Indicates HARS is not directed to perform internal test.
REMARKS: From FCC through DASEC to HARS.
PASS:
If first digit on HOD is 0, 1, 4, or 5, go to paragraph 6–4.
FAIL: Location of fault: HARS, wiring from HARS to DASEC, DASEC. Troubleshoot wiring to isolate
fault (TM 11–1520–238–23–2).
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