CSP-HMI-3 MD Helicopters, Inc.
MAINTENANCE MANUAL
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purpose except as specifically authorized in writing by MD Helicopters, Inc.
Copyright © 1999−2016 by MD Helicopters, Inc.
have accumulated on the magnetic chip
detector.
(17). GEN OUT
:
Generator Out caution light indicates
that the generator voltage is lower than
battery voltage.
(18). AIRFRAME ANTI-ICE FUEL FILTER
:
AirFrame Filter caution light indicates
a impending by-pass or total fuel filter
blockage condition. A pressure sensing
switch closes when differential pressure
across the airframe filter drops to a
preset level forcing a by-pass valve to
open.
(19). AIR FILTER CLOGD
:
Air Filter Clogged caution light indi
cates that the air inlet screen or inlet
particle separator is restricted and
engine performance may be affected.
(20). FLOAT P TST LH/RH
:
Float Press To Test light is illuminated
green when pressed and indicates that
the circuit to inflate the emergency
floats is functioning.
(21). PRESS TO TEST WARN LTS
:
Press To Test Warning Lights illumi
nates the entire warning and caution
light panel when pressed to ensure that
the lights are functioning.
L. Autronics Indicator Lights Dimmer
Assembly Description
The Autronics Indicator Lights Dimmer
Assembly (dimming unit) is a solid state device
associated with caution and warning indicator
lights (Ref. Caution and Warning Indicator
Lights). The unit contains 28 Vdc and ground
test circuits, with isolation diodes, which are
used in PRESS-TO-TEST circuit for lights.
The unit also regulates voltage from 28-14
Vdc for caution and warning lights, instru
ment panel lights and instrument light
dimming. When power is removed from the
unit, the internal relay is automatically reset
to provide 28 Vdc output.
M. Autronics Indicator Lights Dimmer
Assembly Associated Circuits
NOTE:
D The following descriptions of indicator
light circuits are for helicopters with
Slim-Line instrument panel or L/H com
mand T-Panel. The circuitry used on heli
copters with R/H command T-Panel is es
sentially the same except for differences
in circuit breaker position and differences
in circuit connectors to provide for the
horizontal electrical controls console. In
addition, circuit breaker placarding may
differ slightly.
D The dimming unit contains 16 diodes and
other circuit components used in: six neg
ative fault input signal indicator circuits
(Ref. Negative (Ground) Input Fault Cau
tion Light Indicator Circuits) for six cau
tion light indicators; two negative fault
input signal indicator circuits (Ref. Nega
tive (Ground) Input Fault Warning Light
Indicator Circuits) for main rotor trans
mission (XMSN) oil temperature (TEMP)
and pressure (PRESS) warning light indi
cators; a positive input signal indicator
circuit for the START PUMP light indica
tor (Ref. Positive (+28 Vdc) Input Start
Pump Caution Light Circuit); a circuit for
an engine (ENG OUT) warning light indi
cator (Ref. Engine Out (ENG OUT) Warn
ing Light and Horn Circuit); and a panel
and instrument lights dimming circuit
(Ref. Panel and Instrument Lights Dim
ming Circuit). In addition, internal com
ponents permit simultaneous press-to-
test checking of all light indicators (Ref.
Caution and Warning Lights Press-to-
Test Circuits).
D Refer to Caution/Warning System Trou
bleshooting for a partial breakdown of the
dimming unit overall schematic diagram
with associated light indicator circuits
and typical circuits separated by func
tions.
(1). Negative (Ground) Input Fault Caution
Light Indicator Circuits:
Negative input fault caution light
indicator circuits function when a
ground is applied from external sensing
switches to the dimming unit. When
the ground is applied, a current path is
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