MD Helicopters 369-500, Инструкция по техническому обслуживанию

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CSP-HMI-3
MD Helicopters, Inc
.
MAINTENANCE MANUAL
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96-00-00
Page 201
Revision 11
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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.
ELECTRICAL POWER
MAINTENANCE PRACTICES
1. Description and Operation
The helicopter electrical system includes all
power production equipment, and the control
and distribution equipment used to regulate
and transport that power to helicopter
electrical components. Electrical energy for the
system is supplied by a 28 volt direct-current,
150 ampere, engine-driven generator, with a
24 volt nickel-cadmium (nicad) battery. The
system is a nominal 28 Vdc, single-wire
installation with helicopter structure used as
ground return, and incorporates an external
power receptacle. Current helicopters have a
battery ventilation scoop that permits proper
circulation of cooling air inside battery
compartment during flight (Ref. Figure 201).
Control of the system, exclusive of optional
equipment controls, is provided by switches
and circuit breakers (Ref. Sec. 96-30-00).
NOTE:
369FF and 600N model helicopters are
equipped with a generator rated at 200 am­
peres.
All circuits of the system are protected by
push-to-reset or switch type circuit breakers.
Current path return, static charge and radio
frequency bonding jumpers are used at
appropriate locations. (Ref. Figure 205 for
location of major electrical components.)
NOTE:
Information on electrically-actuated
instruments, caution and warning indicator
lights, engine power out warning equip­
ment, the associated sensor or sending units
and other components installed directly on
the instrument panel (excluding control
switches and circuit breakers) is furnished
in Chap. 95. Information on cyclic trim ac­
tuators is contained in Chap. 67, for N
2
gov­
ernor actuator in Chap. 76, and for engine
starting pump in Chap. 28. Information on
the engine ignition system is in Section
96-10-00. Information on the control
switches and circuit breakers is in Section
96-30-00.
2. Miscellaneous DC Main Power and
Control
NOTE:
369D: 003 - 723 did not have an APU or
battery relay. The master switch connects
the dc main power bus to either an external
power source or the nicad battery; or when
OFF, disconnects the bus from either of the
two sources.
The BAT-OFF-EXT PWR (master) switch is
the main power switch for the electrical
system. The master switch completes the
circuit between the battery relay or APU relay
and the dc main power bus by connecting to
the main ground bus. Electrical power for all
electrically-operated equipment in the
helicopter is furnished from the external power
source, generator, or nicad battery through the
dc main power bus. The nicad battery is a
rechargeable, high ampere-hour capacity, 24
Vdc battery. An ammeter allows monitoring of
generator load. For appropriate ammeter type
and location, refer to Section 95-00-00.
3. Electrical System − Fault Isolation
Table 201 provides troubleshooting informa­
tion for the electrical system. Schematics for
equipment functional groups are provided in
applicable sections for use as necessary when
troubleshooting.
Before removing or install­
ing components of electrical
system, ensure that all electrical power
is OFF. If units are not immediately re­
placed, ensure that all electrical con­
nectors are suitably capped and
stowed, and that all loose cables are
properly insulated and stowed, to pre­
vent possibility of shorting. Serious in­
jury or death could result from volt­
ages present in electrical system.
NOTE:
Wire segment continuity checks for
`open' or `short' circuit conditions are as­
sumed to have been completed prior to com­
ponent replacements.
WARNING