TM 1-1520-240-MTF
4-51
(1) 1 Time — Volume of the audio warning
message decreases by one-half.
(2) 2 Times — Audio warning message is
disabled and no longer heard in
headsets.
j. Check dimming control for proper operation
from DIM to BRT.
(1) Check digital display dims and goes out.
(2) Check LO caution lights dim but do not
go out.
X. NAVIGATION and COMMUNICATION CHECK.
1-47.
1. UHF.
a. Transmit and receive.
b. Preset and manual tune.
c. Check both a high and low frequency, e.g.,
over 300 MHz and under 300 MHz.
2. VHF-AM/FM.
a. Transmit and receive.
b. Check both AM and FM bands at high,
medium, and low frequencies.
c. FM Homing.
(1) MODE SEL — DF.
(2) HSI MODE SELECT panel —FM SEL,
check FM SEL lit.
(3) Course deviation bar on HSI — Check
response in turns.
(4) TO-FROM arrows concealed on HSI.
(5) GS and NAV OFF flags concealed on
HSI.
