5-12. Removal and Replacement of 8-Day Clock
5-8. Removal and Replacement of Control, Radio
and Clock Bracket
Set C-7088/ARC-131 (FM Control Head)
(1) Rotate four Dzus fasteners one-quarter turn
(1) Loosen fasteners on each side of the clock
(2) Pull the FM control head out far enough to
(2) Lift off the clock bracket.
reach the electrical connector on the rear of the unit.
(3) Remove the 8-day clock.
(3) Release the electrical connector (twistlock
connector) from the FM control head.
(1) Reinstall the 8-day clock.
(2) Reinstall the clock bracket.
(1) Plug the electrical connector into the rear of
(3) Secure the clock bracket in place with the
the FM control head and secure it.
fasteners located on each side. 5-13. Removal and
(2) Reinstall the FM control head in its mounting
Replacement of Antenna AS-1703/ARC (FM Whip
in the console.
Antenna) Elements Unscrew the antenna element from
(3) Rotate the four Dzus fasteners one-quarter
the coupler. Screw the replacement antenna element
into the coupler. When replacing the FM-1 or FM-2 an-
tenna element, make sure that the AS-1703/AR is
5-9. Removal and Replacement of Receiver-
inserted through the grommet on the standoff mounted
Transmitter, Radio RT-8231ARC-131 (FM
on the side of the aircraft.
5-14. Removal and Replacement of Computer,
Voice Security TSEC/KY-28 (KY-28 Crypto
(1) Release the locking handle catch from its
secured (down) position and pull the locking handle
outward and downward.
(2) Pull out firmly on the locking handle to extract
TSEC/KY-28 may be installed for use
the FM radio from the mounting.
with any one FM radio or all three FM
(1) Set the FM radio on the mounting and slide it
back carefully; make sure the guide pins at the rear
(1) Disconnect the cables from the KY-28 crypto
properly engage the guide pin receptacles.
(2) Lift the locking handle, press inward, and
(2) Connect the cables to plugs P1 and P2 on
secure with the locking handle catch.
the associated security bypass adapter.
(3) Loosen the screw type fasteners on the KY-
28 crypto box mounting bracket or adapter bracket
5-10. Removal and Replacement of Cable
assembly and lift off the KY-28 crypto box.
(1) Secure the KY-28 crypto box on the
associated receiver-transmitter mounting bracket
Always disconnect primary power prior
assembly (FM-3) or adapter bracket assembly (FM-1 or
to removing any cable assembly. All
major cable assemblies that require
(2) Remove the two cables from P1 and P2 on
the associated security bypass adapter plate.
organizational maintenance level use
(3) Connect the cables removed in (2) above to
standard connecting devices.
the mating connectors on the KY-28 crypto box.
special techniques or tools are required
for removal and replacement of these
5-15. Removal and Replacement of Control Indicator
C-8157/ARC (KY-28 Control Head)
5-11. Removal and Replacement of Indicator
(1) Disengage the six Dzus fasteners that hold
the KY-28 control head in the console and pull gently.
(1) Remove the lens cover from the applicable
indicator lamp assembly.
(2) Disengage lamp from the assembly.
(1) Insert a new lamp in the assembly.
(2) Reinstall the lens cover.