TM 1–1520–238–T–3
23–2
Change 4
23–2 SIGNAL NAME:
RADALT VALID IDENT (ACY) RADAR ALT VALID (ACZ)
MEMORY LOCATION: 001530
MEMORY DATA BIT(S):
11
(BINARY)
CONDITION:
(None)
SIGNAL FUNCTION:
Indicates correct address for RADALT.
REMARKS: From RADALT through RH FAB MRTU Type I to FCC.
PASS:
If third digit displayed on HOD is 4, 5, 6, or 7, replace FCC (TM 9–1230–476–20–1).
FAIL: Location of fault: receiver–transmitter, wiring from receiver–transmitter to remote height
indicator, remote height indicator, wiring from remote height indicator to right hand (RH) forward
avionics bay (FAB) multiplex remote terminal unit (MRTU) Type I, RH FAB MRTU Type I.
Troubleshoot reliability wiring to isolate fault (TM 11–1520–238–23–2).
23–3 SIGNAL NAME:
RADAR LO ALT WARNING
MEMORY LOCATION: 001555
MEMORY DATA BIT(S):
17
(BINARY)
CONDITION:
Press the PUSH TO TEST knob on RHI while observing HOD.
SIGNAL FUNCTION:
Indicates LO on video display unit (VDU).
REMARKS: From RADALT through right–hand (RH) forward avionics bay (FAB) multiplex remote
terminal unit (MRTU) Type I to fire control computer (FCC).
PASS:
If the first digit displayed on heads out display (HOD) is 0 or 1, go to paragraph 23–4.
FAIL: Location of fault: receiver–transmitter, wiring from receiver–transmitter to remote height
indicator, remote height indicator, wiring from remote height indicator to pilot matrix
module,wiring from pilot matrix module to RH FAB MRTU Type I, RH FAB MRTU Type I.
Troubleshoot push–to–test wiring and LO WARN wiring to isolate fault
(TM 11–1520–238–23–2).
23–4 SIGNAL NAME:
PILOT LO CONT
MEMORY LOCATION: 000701
MEMORY DATA BIT(S):
18
(BINARY)
CONDITION:
Press the PUSH TO TEST knob on RHI while observing HOD.
SIGNAL FUNCTION:
Displays LO on VDU when RHI is below LO SET altitude.
REMARKS: From FCC to symbol generator.
PASS:
If first digit displayed on HOD is 2 or 3, go to Chapter 14, paragraph 14–92.
FAIL: Location of fault: receiver–transmitter, wiring from receiver–transmitter to remote height
indicator, remote height indicator, wiring from remote height indicator to pilot matrix module,
wiring from pilot matrix module to RH FAB MRTU Type I, RH FAB MRTU Type I. Troubleshoot
wiring to isolate fault (TM 11–1520–238–23–2).
23–5 SIGNAL NAME:
PILOT RADALT
MEMORY LOCATION: 000677
MEMORY DATA BIT(S):
4–17
(SCALAR)
CONDITION:
Press the PUSH TO TEST knob on RHI while observing for 1000 (100) feet on HOD.
SIGNAL FUNCTION:
Pilot’s altitude display in feet.
REMARKS: From FCC to symbol generator.
PASS:
Location of fault if CONDITION is met: replace symbol generator (TM 11–1520–238–23–1).
FAIL: Location of fault: go to paragraph 23–6.
