CSP-HMI-3MD Helicopters, Inc.
MAINTENANCE MANUAL
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96-00-00
Page 207
Revision 11
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.
Each wire in all wiring harnesses is identified
with a wire number incorporating a letter-
number code according to circuit function. A
description of the letter-number code and
complete wiring diagrams for the helicopter
electrical system are as follows:
(1). The initial number (if used) designates
unit number.
(2). The initial letter (of letters) designates
the circuit.
(3). The next number (or numbers) is the
wire number that separates one section
or leg of the circuit from all others.
(4). The following letter indicates segment
of wire in a wire number where the
wire passes through or branches at a
connector or terminal block.
(5). The number (or numbers) following the
segment designation is the standard
AWG wire size.
(6). If the wire is in the ground portion of a
circuit, the suffix N is added to indicate
a ground return.
(7). Where a wire code is duplicated, the
unit number 1 or 2 is prefixed to
differentiate between the two circuits.
A. Electrical Symbols
The graphic electrical symbols in the schemat
ics, and in the wiring diagrams where symbols
are used for clarity, are shown in Figure 206.
B. Electrical Maintenance − Wiring,
Electrical Bonding and Wiring Harnesses
Repair or, as necessary, replace electrical
wiring, connectors, wire-end terminations and
harnesses, and maintain electrical bonds
(structural electrical grounds), in accordance
with FAA AC 43.13-1A (Ref. Table 201, Sec.
01-00-00) and aircraft standard electrical
repair and replacement practices and proce
dures. When necessary, use manufacturer's
maintenance data and special tools for
connectors and wire-end terminations.
NOTE: All connectors and wire-end termina
tion devices are standard components, for
which manufacturer's data and special tools
are normally available either through man
ufacturer's distributors or other outlets
(Ref. Table 201, Sec. 01-00-00).
C. Wire Harness Replacement
Consumable Materials
(Ref. Section 91−00−00)
Item Nomenclature
CM703 Tie strap
CM807 Twine, nylon
(1). Ensure all electrical power is OFF and
disconnect battery.
(2). Disconnect and tag-identify wire
terminal(s) of affected harness.
(3). Disconnect affected wiring harness
connectors (plugs or receptacles),
connections and/or knife splices and
tag-identify all single terminal connec
tions.
NOTE: If necessary, record method of affected
wiring harness routing, clamping and tying
prior to removal to aid at reinstallation.
(4). Route and correctly position replace
ment harness(s).
(5). Replace tying twine (CM807) and
reinstall nylon straps (CM703), if
available. (Substitute tying twine if
nylon straps are not available.)
(6). Reconnect battery and set master
switch to EXT PWR position.
(7). Connect external power source.
(8). Perform operational continuity check(s)
of affected system circuit(s). Refer to
applicable paragraphs in this Section.
As necessary, use schematic and wiring
diagrams.
8. Air/Ground Switch S522
(Effective 369E: 384 & subs, 369FF:. 076 &
subs)
The air/ground switch is located under the
pilot's seat structure just forward of canted
bulkhead at Sta. 78.50. Audible headset
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