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this is not the exterior of the wire, the major difference is the extra stiffness that it imparts on the
wire sample. As a sample wears, the glass fiber may become exposed and have an impact on the
wires it contacts. Ten wire constructions commonly used in aircraft wiring applications were
selected for the test program and were included in both single and twisted pair configurations.
The wire types and their combinations with other wire types are shown in table 1. Seven of the
wire types tested are general-purpose types designed for use in open wiring (airframe)
applications based on AS 50881. The other three insulation types, mineral-filled
polytetrafluoroethylene (PTFE), PTFE with glass braid, and PVC/glass/nylon, are generally for
applications with especially high abrasion stresses.
The wires tested were 22 gauge, with the exception of the modified and XLETFE and crosslinked
polyalkene-imide (XPI) alloy insulated wires that were 24 gauge. These wire sizes are
typical of open wiring applications that use 22-gauge wire with an annealed copper conductor or
24 gauge with a higher tensile strength copper alloy conductor. The original objective was for
all the wires to have the same conductor size, but the two 24-gauge wires were added to the
program because of the high usage of that wire size in aircraft. It was also expected that these
small-gauge wires, with thinner insulation and smaller wire-to-wire contact areas, would exhibit
pronounced damage more quickly.
6
TABLE 1. WIRE TYPES EVALUATED
Wire
Code* Description
1 PVC/glass/nylon—Annealed copper conductor insulated with an extruded PVC
covered by a glass fiber braid, then coated with an extruded Polyamide per MIL-W-
5086/2-22.
2 Polyimide—Annealed copper conductor insulated with a tape-wrapped aromatic
polyimide, and coated with an extruded aromatic polyimide resin, per BMS13-
51T08.
3 XPI, alloy—Copper alloy conductor insulated with a cross-linked extruded aliphatic
polyimide, per Raychem Spec 88A, 24 AWG.
4 XLETFE—Annealed copper conductor insulated with a modified and cross-linked
extruded XLETFE, per BMS13-48T08.
5 XLETFE, alloy—Copper alloy conductor insulated with a modified and cross-linked
extruded XLETFE, per MIL-W-22759/42-24.
6 PTFE—Annealed copper conductor insulated with polytetrafluoroethylene (PTFE),
per MIL-W-22759/9-22.
7 MF-PTFE—Annealed copper conductor insulated with a mineral-filled PTFE, per
MIL-W-22759/8-22.
9 PTFE/glass—Annealed copper conductor insulated with multilayered PTFE and
covered with a glass fiber braid, per MIL-W-22759/1-22.
10 PI/PTFE—Annealed copper conductor insulated with a tape-wrapped aromatic
polyimide, and covered with a tape-wrapped PTFE, per BMS13-60T19G22.
11 PI/PTFE Alloy—Copper alloy conductor insulated with a tape-wrapped aromatic
polyimide and covered with a tape-wrapped PTFE, per BMS13-60T04G22.
*Tape wrap PTFE (M16878), wire code 8, was originally considered for the program, but was removed since it is
not typically used in open wire applications.
4.3 WIRE BUNDLE CONFIGURATIONS.
Each wire bundle in Groups I and II consisted of 20 wires of either the same wire type or 10
wires of two different wire types. Each bundle contained 12 single wires and 4 twisted pair
wires, which provided the opportunity to evaluate the interactions between single-end wires,
twisted pair wires, and between twisted pairs and single-end wires in each bundle. For bundles
containing two wire types, half of the singles and half of the twisted pairs were of each wire type.
Tiedown straps, lacing string, and cushion clamps were used on the bundles to contain the wires
and secure them to the vibration fixtures. Detailed descriptions of the wire bundles are in
appendix B.
4.4 WIRE BUNDLE COMBINATIONS.
Since 10 wire types were selected for the program, up to 55 different wire combinations could be
evaluated, including each wire type in a nonmixed condition. However, due to the limitations of
the program funding and vibration test fixturing, the 48 combinations represented by the
unshaded blocks in table 2 were selected for group I.
7
TABLE 2. WIRE COMBINATIONS TESTED IN GROUP I
Wire Type
1
PVC/
G/N
2
PI
3
XPI
Alloy
4
XLETFE
5
XLETFE
Alloy
6
PTFE
7
MF-PTFE
9
PTFE/
Glass
10
PI/PTFE
11
PI/PTFE
Alloy
1
PVC/
G/N
2
PI
3
XPI
Alloy
4
XLETFE
5
XLETFE
Alloy
6
PTFE
7
MF-PTFE
9
PTFE/
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