TM 55-1520-240-T
16-196 Change 24
16-5.3 AN/ALE-47 COUNTERMEASURES DISPENSER SYSTEM OPERATIONAL CHECK (Continued)
16-5.3
TASK
RESULT
NOTE
Ensure all DCDU INHIBIT LEDs remain
illuminated when performing steps 19 – 22.
28. Press DCDU ENT/BIT switch (25) momentarily to
When IBIT is complete, MAINT MODE??? prompt will
select maintenance mode.
appear.
29. While MAINT MODE??? is displayed, press DCDU
The following displays appear:
ENT/BIT switch (25) momentarily to display the DCDU
OFP # XXXX MDF # XXXX
and sequencer firmware identification numbers.
CCU FIRM ID ####
SEQ 1A ID ####
SEQ 2A ID ####
SEQ 1A SAFE
SEQ 2A SAFE
30. When HIST DATA??? appears, press DCDU ENT/BIT
System fault messages are displayed. Refer to table at
switch (23) momentarily.
end of this task for explanation of fault messages. After
fault messages are displayed, CLR FLT LST is displayed.
NOTE
The number (inventory) displayed on the DCDU
will vary based on the number of CDTs being used
to perform the AN/ALE-47operational check.
Examples:
1 CDT installed: 10 10 _ _ 10 will be displayed
2 CDTs installed: 20 20 _ _ 20 will be displayed
3 CDTs installed: 30 30 _ _ 30 will be displayed
4 CDTs installed: 40 40 _ _ 40 will be displayed
31. Press DCDU ENT/BIT switch (25) momentarily after
O1: 20 O2: 20 CH: _ _ FL: 20 is displayed on DCDU.
CLR FAULT LIST? prompt appears to clear the MFL.
NOTE
The CDT has a battery saver feature which
will turn the CDT off after approximately 15
minutes of inactivity. If this occurs, set CDT
MODE switch (18) to OFF, then back to FIRE
TEST; press RESET TEST button.
32. Adjust DCDU LED indicator (5) brightness from dim
DCDU LED indicator goes from bright to dim as lighting
to bright; set as desired using ALE-47 dim switch (2)
control switch is rotated.
located on miscellaneous control panel (3).
TASK
RESULT
33. Press DCDU INHIBIT O1, O2, CH, FL, RWR, JMR,
LED for each switch goes out as switch is
and MWS switches (24).
depressed.
34. Ensure sequencer switches (43 and 44) are set as
follows: No. 1 sequencer (32): 1/A; No. 2 sequencer
(26): 2/A.
35. Remove safety pin (30) from AN/ALE-47 safety
switch (31).
36. Set LDG GR SW BYPASS switch (28) on LDG GR
LDG GR SW BYPASS light (29) on LDG GR BYPASS
BYPASS STATUS panel (27) to BYPASS (up).
STATUS panel illuminates.
If LDG GR SW BYPASS light (29) on LDG GR BYPASS
STATUS panel does not illuminate, troubleshoot per
Task 16-5.13.
37. Set DCDU MODE switch (7) to MAN and MANUAL
O1: 20 O2: 20 CH: _ _ FL: 20 is displayed on DCDU.
switch (6) to 1.
If DCDU does not display full simulated payload module
quantities, check DCDU for BIT failure messages. If no BIT
failure messages are displayed, verify that CDTs are
installed correctly and powered up.
NOTE
Loose, damaged or dirty contacts for the fire pins
and ground spring of the dispenser assemblies
can cause misfires of the expendables.
38. Press and release FLARE DISP button (22) on pilot’s
Expendable count on DCDU counts down by XX; CDTs
cyclic stick grip (23) one time.
count up by XX. (NOTE: XX represents the expendable
count as determined by the MDF loaded in the CMDS and
the number of CDTs installed).
If DCDU does not indicate correct dispense count, isolate
faulty LRU; if CDT does not indicate correct count, go to
Task 16-5.10.
39. Dispense all remaining simulated payloads by
O1: 0 O2: 0 CH:_ _ FL: 0 is displayed on DCDU;
repeatedly pressing FLARE DISP button (22).
30 is displayed on CDTs.
If CDT does not show all expendables fired, isolate the
faulty LRU; remove and replace LRU per TM 55-1520-240-
23-10.
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