CSP-HMI-3 MD Helicopters, Inc.
MAINTENANCE MANUAL
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96-30-00
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.
(K312) if an over voltage, over current or
reverse current condition exists. Power is
stored in a 24 Vdc high ampere hour nickel-
cadmium battery BT101. If the generator
output is excessively low, a reverse current
condition will develop between the battery and
generator. The GCU current sense line will
trip the GEN switch removing power from the
GCU. An internal ground is provided by the
GCU to illuminate the GEN OUT indicator.
The GEN circuit breaker type switch protects
the generator field circuit from currents over
15 amperes and provides power to the GCU.
Auxiliary power receptacle J100, protected by
APU relay K309, provides an alternate source
of 28 Vdc power for the helicopter when on the
ground. The BATTERY-OFF-EXT PWR
switch S2 directs power from either APU relay
K309 or battery relay K310 to main dc power
busses.
4. Power Distribution Center
(Effective on the following helicopters only:
369E helicopter S/N 384 and subs,
369FF helicopter S/N 076 and subs,
500N helicopters S/N 001 and subs and
600N helicopters S/N 0003 and subs)
The power distribution center is located just
aft of Sta. 64.37 canted bulkhead, under the
pilot seat structure. The power distribution
center consists of battery relay (K310), ground
power relay (K309), landing light relay (K101),
over voltage diodes (CR2001, CR2002,
CR2003), ammeter shunt (AS301) and forward
line contactor (K308).
The over voltage diodes provide protection to
ship electrical systems and any optional
avionics systems from voltage spikes or
improper ground power unit supply voltages.
The ammeter shunt increases load current
measurement accuracy and improved reliabil
ity. The forward line contactor isolates the
battery and ship power from the main feeder.
An aft line contactor located in the engine bay
on the oleo support fitting between Sta. 124.0
and 137.50. The contactor isolates the genera
tor from the main feeder.
5. Power Distribution Center Replacement
Consumable Materials
(Ref. Section 91−00−00)
Item
Nomenclature
CM217 Isopropyl alcohol
CM703 Tie strap
CM815 Solder
(1). Ensure all electrical power is OFF;
disconnect battery.
(2). Remove left foot support fairing panel
(Ref. Sec. 52-50).
(3). Release velcro attaching points secur
ing power distribution center cover
plate.
(4). Remove tie straps (CM703) as required
to gain access to component hardware.
(5). Identify, tag and disconnect wires from
relays.
(6). Identify, tag and desolder (CM815)
wires from diodes. Remove diodes from
plate.
(7). Remove attaching hardware from shunt
bar, terminal 2.
(8). Remove attaching hardware securing
relays to plate, and shunt bar to plate
bracket.
(9). Remove attaching hardware securing
plate to helicopter.
(10). Repair and or replace components as
necessary.
(11). Install components onto plate.
(12). Reconnect wiring and secure with
applicable hardware and or solder
(CM815); remove all tags and ensure
proper wire end insulation.
(13). Clean solder joints with alcohol
(CM217).
(14). Position assembled plate over mounting
holes and secure to helicopter.
(15). Arrange wiring to from smooth integra
tion with existing wire harness; use tie
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