TM 55-1520-240-T
18-2.3
ALTITUDE VOICE WARNING SYSTEM OPERATIONAL CHECK
18-2.3
INITIAL SETUP
Applicable Configurations:
References:
All
TM 11-1520-240-23
TM 55-1520-240-23
Tools:
Electrical Repairer's Tool Kit,
Equipment Condition:
NSN 5180-00-323-4915
TM 55-1520-240-23:
Battery Connected
Materials:
Electrical Power Off
None
Hydraulic Power Off
Altitude Voice Warning System Visual Check
Personnel Required:
Performed (Task 18-2.2)
Aircraft Electrician (2)
TASK
RESULT
CHECK CIRCUIT BREAKERS
1. Check that the following circuit breaker on
If circuit breaker is open (1), close it.
No. 1 pdp are closed:
INTPH LH (1)
2. Check that the following circuit breakers on
If any circuit breaker is open (2 and 3), close it.
No. 2 pdp are closed:
INTPH RH (2)
RAD ALT (3)
3. Start APU. Refer to task 15-1.4
APU ON capsule shall come on.
CHECK AVWS OPERATION
NOTE
• The following checks will only cover the Altitude Voice Warning portion of the Radar Altimeter operation.
For indication discrepancies, refer to TM 11-1520-240-23.
• Ensure that the pilot, copilot, and aft interphone stations are all operational.
4. With the pilot's Radar Altimeter (4) turned ON
The warning message "ALTITUDE LOW, TOO
and the OFF Flag (5) not visible, and with a
LOW" should NOT be heard. If this message is
headset connected to the pilot's headset jack,
heard, go to task 18-2.6.
rotate the LO SET knob (6) to position the LO
SET Index (7.) just above the OFF detent.
Adjust the HI SET knob (8) to position the HI
SET Index (9) at 100 feet.
TASK
RESULT
5. Adjust the LO SET Index (7) to approximately the
The warning message "ALTITUDE LOW, TOO LOW"
10 foot position on the indicator.
shall be heard at FULL volume. If this message is NOT heard
or volume is NOT FULL, go to task 18-2.4.
6. Momentarily depress the PUSH-TO-TEST knob
The volume of the low altitude warning message
(6) once.
shall decrease by one-half (1/2). If volume stays full, or NOT
heard at all, go to task 18-2.5.
7. Reset the LO SET Index (7) to a point just above
The low altitude warning message shall be heard at
the OFF detent, wait 11 seconds, and return LO
FULL volume. If message is NOT heard at all, or if
SET index to the 10 feet mark.
volume is NOT full, go to task 18-2.4.
8. Press and hold the PRESS-TO-TEST knob (8) to
The warning message "ALTITUDE HIGH, CHECK
activate the self-test.
ALTITUDE" shall be audible at FULL volume. If message is
NOT heard, or if volume is NOT full, go to task 18-2.4.
9. Release the PUSH-TO-TEST knob.
The warning message "ALTITUDE LOW, TOO LOW" shall be
again heard, at FULL volume. If message is NOT heard, or if
volume is NOT full, go to task 18-2.4.
10.
Repeat steps 4 thru 9 with a headset connected Results shall be as specified in steps 4 thru 9. If
to the copilot's headset jack.
altitude warning messages are not audible, even after
replacing Radar Altimeter (4), go to task 18-2.4.
11.
Repeat steps 4 thru 9 with a headset connected Results shall be as specified in steps 4 thru 9. If
to the hoist operator's headset jack.
altitude warning messages are not audible, even after
replacing Radar Altimeter (4), go to task 18-2.4.
FOLLOW-ON MAINTENANCE:
TM 55-1520-240-23:
Battery Disconnected
Electrical Power Off
18-52
Change 18
