MD Helicopters 369-500, Инструкция по техническому обслуживанию

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CSP-HMI-3
MD Helicopters, Inc
.
MAINTENANCE MANUAL
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Revision 7
95-30-00
The information disclosed herein is proprietary to MD Helicopters, Inc.
Neither this document nor any part hereof may be reproduced or transferred to
other documents or used or disclosed to others for manufacturing or any other
purpose except as specifically authorized in writing by MD Helicopters, Inc.
Copyright
©
1999 − 2016 by MD Helicopters, Inc.
amplitude audio warning tone No. 3 is applied
directly to headsets so that audible warning is
present in headsets in event of failure of ICS
system equipment.
When either N
1
or N
R
sensing occurs, the auto
reig28 Vdc control circuit supplies
steady state +28 Vdc for engine automatic
reignition equipment (if installed).
N
R
disable switch Sl99 furnishes a ground to
the EPO warning control unit to disable N
R
sensing and prevent engine out light flashing
and audible warnings at ending idle and cutoff
positions. Diodes in the Autronics Indicator
Lights Dimmer Assembly provide directional
paths for flashing light currents, and for test
voltages and grounds during press-to-test
check of lights. Resistor and diode board
TB106 furnishes isolation and correct termina­
tion impedance for audio warning tone No. 3.
For information on internal functioning of the
EPO warning control unit and dimming unit.
15. Autronics EPO Warning Control Unit
(369D/E/FF − 500N)
The EPO warning control unit is a sealed,
solid state device that controls warning light
indicator flashing and provides drive for the
audible warning horn and tone signals for
headsets in event of engine failure or low main
rotor speed. The EPO warning control unit
provides pulsating dc voltage through the
dimming unit and warning light circuits to
flash the warning light.
A. Slim − Line Instrument Panels
The EPO warning control unit is installed at
the lower right interior of the instrument
panel console on Model 369D helicopters S/N 3
- 1149, or at the lower left interior of the
instrument panel console on Model 369D
helicopters S/N 1150 and subsequent.
B. R/H command T − Panels
The EPO warning control unit is installed at
the lower right interior of the lower support
structure.
C. L/H command T − Panels
The EPO warning control unit is installed at
the lower right interior of the instrument
panel console.
The EPO warning control unit is sealed and
has no adjustments; an internal defect
requires replacement of the unit (Ref. Autron­
ics EPO Warning Control Unit Operational
Check for information on checking the unit).
NOTE:
Internal schematic diagrams of the unit
are not provided; internal maintenance is
not practical.
D. Engine Power Out Warning Control Unit
Circuits
The EPO warning control unit contains N
1
and
N
R
speed-sensing circuits, an N
R
speed-sens­
ing time-delay circuit, circuits for flashing and
tone control, two tone generators, two flasher
circuits and a tone interrupt circuit. (Ref.
electrical system wiring diagrams in Chap. 96
for interconnecting wiring information on the
caution and warning lights system.)
E. Low Main Rotor Speed (N
R
) Sensor
Circuits
Low N
R
speed-sensing functions incorporate
disable and time delay circuits. Application of
a disable ground to the unit causes the disable
circuits to deactivate N
R
sensing which
prevents the warning indications while the
disable ground is applied. The time delay
keeps N
R
sensing disabled for 3.5 +0.5 seconds
after removal of the disable ground. When
activated, the N
R
sensing circuits activate and
control the flasher and tone control circuits.
The flasher and tone control circuits drive an
engine out light flasher which provides
pulsating dc voltages for flashing the engine
out warning light and driving the audible
warning horn. The flasher and tone control
circuits also simultaneously activate audio
tone generators Nos. 1 and 3 which supply an
audible warning tone for headsets.
NOTE:
Audible warning tone generators Nos. 1
and 3 are activated and controlled by either
N
R
sensing or N
1
sensing (Ref. Engine Out
(N
1
) Frequency Sensor Circuits).
In Model 369D/E helicopters with C20 engine,
the N
R
speed-sensing circuit senses low N
R
speed at approximately 98% N
R
RPM (equiva­
lent to tachometer generator output ac voltage
with a frequency of 68.6 +0.7 Hz), or less.
In Model 369FF helicopters with C30 engine,
the N
R
speed-sensing circuit senses low N
R
speed at approximately 95% RPM (equivalent