TM 55-1510-220-MTF
PROCEDURE
TROUBLESHOOTING
REFERENCE
F.
AVIONICS FLIGHT CHECKS (CONT)
NOTE
The first digit from the left indicates "1" for NAV mode. The
second and third digits will be blank unless a malfunction code
is indicated. The fourth digit is used for stored heading and
shall be blank. The fifth digit is decremented at certain time
intervals when using TACAN update. This provides an
indication of the relative quality of position updating obtained.
The sixth digit indicates operating mode and will read "4" to
indicate TACAN updating.
(4) If malfunction codes occur, press and release the TEST switch repeatedly, recording all
malfunction codes until the second and third digits again indicate an action or code, or go
blank. Refer to TM 55-1510-220-10 for code definitions.
(5) WARN lamp - Check dim.
m. UTM Position - Check as follows:
(1) Data selector - UTM POS.
(2) Left-hand display - Read northing in kilometers.
(3) Right-hand display - Read zone, then easting in kilometers.
4-18
