DOT/FAA/AR-05/26 

Office of Aviation Research 

Washington, D.C. 20591

The Effects of Mixed Wire Types 

in Aircraft Electrical Wiring 

Interconnection Systems 

September 2005 

Final Report 

This document is available to the U.S. public 

through the National Technical Information 

Service (NTIS), Springfield, Virginia 22161. 

U.S. Department of Transportation 

Federal Aviation Administration
NOTICE 

This document is disseminated under the sponsorship of the U.S. 

Department of Transportation in the interest of information exchange. The 

United States Government assumes no liability for the contents or use 

thereof. The United States Government does not endorse products or 

manufacturers. Trade or manufacturer's names appear herein solely 

because they are considered essential to the objective of this report. This 

document does not constitute FAA certification policy. Consult your local 

FAA aircraft certification office as to its use. 

This report is available at the Federal Aviation Administration William J. 

Hughes Technical Center's Full-Text Technical Reports page: 

actlibrary.tc.faa.gov in Adobe Acrobat portable document format (PDF). 
 Technical Report Documentation Page

1. Report No.

DOT/FAA/AR-05/26

2. Government Accession No. 3. Recipient's Catalog No.

5. Report Date 

September 2005

 4. Title and Subtitle 

THE EFFECTS OF MIXED WIRE TYPES IN AIRCRAFT ELECTRICAL 

WIRING INTERCONNECTION SYSTEMS 6. Performing Organization Code

CNEA50 

7. Author(s)

Joseph Kurek and James Meiner 

8. Performing Organization Report No. 

50-05-054 

10. Work Unit No. (TRAIS) 

 

9. Performing Organization Name and Address

Raytheon Technical Services Company 

6125 East 21st Street 

Indianapolis, IN 46219-2058

11. Contract or Grant No.

 DTFACT 03-C-00008 

13. Type of Report and Period Covered

 Final Report 

 03/02-8/03

12. Sponsoring Agency Name and Address

U.S. Department of Transportation 

Federal Aviation Administration

Office of Aviation Research 

Washington, DC 20591

14. Sponsoring Agency Code

 ANM-117

15. Supplementary Notes 

The FAA William J. Hughes Technical Center COTR was Cesar Gomez.

16. Abstract 

Original aircraft manufacturers have designed and built aircraft with various wire types due to the improvement of technology, 

materials, and processing of wire. New aircraft may have multiple wire types in the same aircraft to meet various environmental 

zone requirements. Wiring sections may be modified or rewired with the same wire that was originally installed in the aircraft or 

with a newer, more advanced wire, thus mixing wire types in bundles. Little data has been generated and published indicating 

whether mixing wire types creates problems with the long-term integrity of the electrical wiring. The objective of this research 

was to assess past and current guidelines, to review prior research and test data, and to perform additional testing to determine the 

effects of mixed wire types in electrical wiring interconnection systems in aged aircraft. Where applicable, develop 

recommendations regarding the mixing of wire types in aircraft applications. 

17. Key Words 

Aged aircraft, Mixed wire 

18. Distribution Statement 

This document is available to the public through the National 

Technical Information Service (NTIS) Springfield, Virginia 

22161.

19. Security Classif. (of this report) 

 Unclassified

20. Security Classif. (of this page) 

 Unclassified

21. No. of Pages 

 104 

22. Price

Form DOT F1700.7 (8-72) Reproduction of completed page authorized 
ACKNOWLEDGEMENTS 

Assistance from the following personnel was necessary: 

Airbus – Dominique Chevant 

Air Force – George Selenski 

Boeing – Don Andersen 

Bombardier – Petar Glamoclija 

Lockheed Martin – Bobby Crumb 

Raychem – Steve Zingheim 

SR Technics – Lukas Zuellig 

Raytheon Technical Services Company: 

Greg AmRhein 

Emmett Perkoski 

John Sprung 

Chris Hayes 

Don Kuhn 

Gary Burgan 

Ronnie Peterson 

Tim Ward 

Mike Rediske 

Andy Brown 

Roy McMahon 

John Jacobs 

iii/iv
TABLE OF CONTENTS 

Page 

EXECUTIVE SUMMARY xiii 

1. INTRODUCTION 1 

1.1 Purpose 1 

1.2 Background 1 

1.2.1 Wire Installation 1 

1.2.2 Design Options 1 

1.2.3 Investigation Reason 1 

2. APPROACH 1 

3. REVIEW OF DOCUMENTATION 2 

3.1 Review of Regulations, Proposed Regulations, and Design Specifications 2 

3.2 Aircraft Wiring Practices 2 

3.2.1 Original Aircraft Manufacturers Wiring Practices 2 

3.2.2 Commercial Maintenance and Operator Wiring Practices 3 

3.2.3 Modification Facilities 3 

3.2.4 Military Maintenance and Operation Wiring Practices 3 

3.3 Review of Service Data 4 

3.4 Review of Prior Research and Test Data 4 

3.5 Documentation Review Summary 4 

4. TEST PROGRAM 4 

4.1 Test Plan 5 

4.2 Specimen Description 6 

4.3 Wire Bundle Configurations 7 

4.4 Wire Bundle Combinations 7 

4.5 Crush Test Wire Combinations 9 

5. DISCUSSION AND RESULTS 10 

5.1 Group I Test Results 10 

5.1.1 Visual Observations on Mounted Bundles 10 

5.1.2 Electrical Testing 10 

5.1.3 Wire-to-Wire Wear 11 

v
5.1.4 Wire Wear From Clamps 18 

5.1.5 Wire Wear From Straps and Lacing String 20 

5.1.6 Wire Wear From Vibration Fixture Plate 21 

5.1.7 Wear of Support Components 21 

5.1.8 Wear of Single Wires vs Twisted Pairs 21 

5.2 Group II Test Results 22 

5.2.1 Visual Observations 22 

5.2.2 Electrical Testing 22 

5.2.3 Wire-to-Wire Wear 22 

5.2.4 Wire Wear From Clamps 35 

5.2.5 Wire Wear From Straps and Lacing String 38 

5.2.6 Wire Wear From Vibration Fixture 39 

5.2.7 Wear on Support Components 40 

5.2.8 Wear of Single Wires Versus Twisted Pairs 40 

5.3 Test Groups I and II Comparison 40 

5.4 Group III Crush Test Results 41 

5.5 Comparison to Previous Data 42 

6. SUMMARY AND RECOMMENDATIONS 43 

6.1 Summary 43 

6.2 Recommendations 43 

7. RELATED DOCUMENTATION 44 

8. REFERENCES 46 

APPENDICES 

A—Regulations, Standard Practices, and Previous Test Documentation 

B—Test Program 

C—Test Data 

D—Additional Photographic Documentation

vi
LIST OF FIGURES 

Figure Page 

1 Group I Testing: PVC/Glass/Nylon (Wire Code 1) Wire Damage After 500 

Hours of Vibration Conditioning 11 

2 Group I Testing: PI (Wire Code 2) Wire Damage After 500 Hours of Vibration 

Conditioning 12 

3 Group I Testing: Aliphatic PI, Alloy (Wire Code 3) Wire Damage After 500 

Hours of Vibration Conditioning 12 

4 Group I Testing: XLETFE (Wire Code 4) Wire Damage After 500 Hours of 

Vibration Conditioning 13 

5 Group I Testing: XLETFE, Alloy (Wire Code 5) Wire Damage After 500 Hours 

of Vibration Conditioning 13 

6 Group I Testing: PTFE (Wire Code 6) Wire Damage After 500 Hours of 

Vibration Conditioning 14 

7 Group I Testing: PTFE, Mineral-Filled (Wire Code 7) Wire Damage After 500 

Hours of Vibration Conditioning 14 

8 Group I Testing: PTFE/Glass Braid (Wire Code 9) Wire Damage After 500 

Hours of Vibration Conditioning 15 

9 Group I Testing: PI/PTFE (Wire Code 10) Wire Damage After 500 Hours of 

Vibration Conditioning 15 

10 Group I Testing: PI/PTFE, Alloy (Wire Code 11) Wire Damage After 500 Hours 

of Vibration Conditioning 16 

11 Wire Interactions in Group I Mixed Bundles 17 

12 Moderate Wire-to-Wire Wear on Group I XPI in Bundle Mixed With PTFE 18 

13 Moderate Wire-to-Wire Wear in Group I Nonmixed XPI Bundle 18 

14 Moderate Wire Wear From Clamps on Nonmixed XPI Bundle in Group I 19 

15 Moderate Wire Wear From Clamp on PI/PTFE and XPI in Group I 19 

16 Group I: Tightness of Clamp vs Wear From Wire 19 

17 Group I: Tightness of Clamp vs Wear From Clamp 20 

18 Moderate Wear on Clamp From PVC/Glass/Nylon and MF-PTFE Group I Bundle 21 

vii
19 Moderate Wear of Clamp From Nonmixed PTFE/Glass Bundle in Group I 21 

20 Group IIF Testing: PVC/Glass/Nylon (Wire Code 1) Wire Damage After 250 

Hours of Vibration Conditioning 23 

21 Group IIF Testing: PI (Wire Code 2) Wire Damage After 250 Hours of Vibration 

Conditioning 23 

22 Group IIF Testing: Aliphatic PI, Alloy (Wire Code 3) Wire Damage After 250 

Hours of Vibration Conditioning 24 

23 Group IIF Testing: XLETFE (Wire Code 4) Wire Damage After 250 Hours of 

Vibration Conditioning 24 

24 Group IIF Testing: PTFE, Mineral-Filled (Wire Code 7) Wire Damage After 250 

Hours of Vibration Conditioning 25 

25 Group IIF Testing: PTFE/Glass Braid (Wire Code 9) Wire Damage After 250 

Hours of Vibration Conditioning 25 

26 Group IIF Testing: PI/PTFE (Wire Code 10) Wire Damage After 250 Hours of 

Vibration Conditioning 26 

27 Group IIF Testing: PI/PTFE, Alloy (Wire Code 11) Wire Damage After 250 

Hours of Vibration Conditioning 26 

28 Wire Interactions in Group IIF Mixed Bundles 28 

29 Moderate Wire-to-Wire Wear in Group IIF Nonmixed PI Bundle 28 

30 Moderate Wire-to-Wire Wear on PI When Mixed With MF-PTFE in Group IIF 28 

31 Group IIM Testing: PVC/Glass/Nylon (Wire Code 1) Wire Damage After 250 

Hours of Vibration Conditioning 29 

32 Group IIM Testing: PI (Wire Code 2) Wire Damage After 250 Hours of Vibration 

Conditioning 29 

33 Group IIM Testing: Aliphatic PI, Alloy (Wire Code 3) Wire Damage After 250 

Hours of Vibration Conditioning 30 

34 Group IIM Testing: XLETFE (Wire Code 4) Wire Damage After 250 Hours of 

Vibration Conditioning 30 

35 Group IIM Testing: PTFE, Mineral-Filled (Wire Code 7) Wire Damage After 

250 Hours of Vibration Conditioning 31 

36 Group IIM Testing: PTFE/Glass Braid (Wire Code 9) Wire Damage After 250 

Hours of Vibration Conditioning 31 

viii
37 Group IIM Testing: PI/PTFE (Wire Code 10) Wire Damage After 250 Hours of 

Vibration Conditioning 32 

38 Group IIM Testing: PI/PTFE, Alloy (Wire Code 11) Wire Damage After 250 

Hours of Vibration Conditioning 32 

39 Wire Interactions in Group IIM Mixed Bundles 34 

40 Moderate Wire-to-Wire Wear on XPI in Nonmixed Group IIM Bundle 34 

41 Severe Wear on PI/PTFE From Clamp When Mixed With XPI in Group IIF 35 

42 Group IIF: Tightness of Clamp vs Wear From Wire 36 

43 Group IIF: Tightness of Clamp vs Wire Wear From Clamp 36 

44 Severe Wear of PTFE/Glass Wire From Clamp in Group IIM Nonmixed Bundle 37 

45 Group IIM: Tightness of Clamp vs Wear From Wire 37 

46 Group IIM: Tightness of Clamp vs Wire Wear From Clamp 38 

47 Moderate Wear of XPI and PI/PTFE From Strap in Group IIF 39 

48 Moderate Wear of PI/PTFE From Strap When Mixed With MF-PTFE in 

Group IIF 39 

49 Moderate Wear on PI From Lacing String When Mixed With MF-PTFE in 

Group IIF 40 

50 MF-PTFE Wire Damaged From PI Wire in the 80-Pound Crush Test 42 

51 PI/PTFE Alloy Wire Damaged From PI/PTFE Wire in the 80-Pound Crush Test 42 

52 XLETFE Wire Damaged by PI Wire in the 120-Pound Crush Test 42 

53 PI/PTFE Alloy Wire Damaged by Same Wire Type in the 120-Pound Crush Test 42 

ix
LIST OF TABLES 

Table Page 

1 Wire Types Evaluated 7 

2 Wire Combinations Tested in Group I 8 

3 Wire Combinations Tested in Group II 9 

x
LIST OF ACRONYMS 

AC Advisory Circular 

CFR Code of Federal Regulations 

DWV Dielectric withstand voltage 

EWIS Electrical wiring interconnect system 

FAA Federal Aviation Administration 

IR Insulation resistance 

NAC Naval Avionic Center 

OAM Original aircraft manufacturer 

PI Polyimide 

PTFE Polytetrafluoroethylene 

PVC Polyvinylchloride 

XLETFE Cross-linked ethylene-tetrafluoroethylene 

XPI Cross-linked polyalkene-imide 

xi/xii
EXECUTIVE SUMMARY

Original aircraft manufacturers have designed and built aircraft with various wire types. This 

occurred because the technology, materials, and processing of wire has continually improved. 

New aircraft may have multiple wire types in the same aircraft to meet various environmental 

zone requirements. Wiring sections may be modified or rewired with the same wire that was 

originally installed in the aircraft or with a newer, more advanced wire, thus mixing wire types in 

bundles. Little data has been generated and published indicating whether mixing wire types 

creates problems with the long-term integrity of the electrical wiring. 

An assessment of the past and current guidelines regarding the presence of multiple wire types 

was performed. Conclusions were made regarding the effects of multiple wire types mixed 

together in the electrical wiring interconnect system (EWIS), based on test results, and 

recommendations are made regarding the mixing of multiple wire types within the EWIS during 

design, repair, and maintenance of the EWIS. 

None of the documents reviewed specifically addressed or restricted mixing of dissimilar wire 

types in bundles, but regulations stipulated that the wires selected must meet the environmental, 

application, interface, and design requirements. 

Accelerated vibration testing of mixed and nonmixed wire bundles was performed both with and 

without hydraulic fluid and metal shavings contamination. The results indicated that none of the 

ten wire types tested exhibited accelerated wear characteristics in mixed bundles compared to 

nonmixed bundles. No electrical failures were attributed to mixing of wire types within a bundle 

during laboratory testing. Many of the wire types, however, exhibited significant wear from 

clamps and structure in both the contaminated and uncontaminated conditions. 

Routine inspections of all wire types should continue in aging aircraft to ensure that the electrical 

wire maintains physical and electrical integrity and to monitor the wire for signs of wear from 

wires, clamps, and the aircraft structure. Inspection of the clamped areas should be emphasized, 

with the clamp to wire tightness being evaluated. 

xiii/xiv
1. INTRODUCTION.

1.1 PURPOSE.

The purpose of this study was to determine the effects of mixing wire types in aged aircraft and 

to develop Federal Aviation Administration Advisory Circular (AC) or regulation 

recommendations as applicable to the mixing of wire types in aircraft applications. 

1.2 BACKGROUND.

1.2.1 Wire Installation. 

Original aircraft manufacturers (OAM) have designed and built aircraft with various wire types. 

This occurred because the technology, materials, and processing of wire has continually 

improved. Aircraft wiring is not subject to a service life and mandatory replacement. The 

airworthiness of aircraft wiring is managed through inspections and maintenance processes. 

Wiring sections may be modified or rewired with the same wire that was originally installed in 

the aircraft, or with a newer, more advanced wire, thus mixing wire types in bundles. As aircraft 

systems are modified or updated, the same airframe wire may not be available or desirable to 

use. During maintenance and repair, newer or different wire may be used to replace older wire. 

In these cases, different wire types may be placed together within a harness, or may be located in 

adjacent harnesses. 

1.2.2 Design Options. 

It is not uncommon to have multiple wire types used for a new aircraft design because of 

extreme environmental differences between aircraft zones. Some zones require more rugged 

wire types than general-purpose wire zones. The designer has the option to protect the generalpurpose wire in the extreme zones or to use an alternate wire type. In many cases, the alternate 

wire type is a specialty wire used for enhanced performance or weight savings. The end result is 

mixed wire bundles for the life of the aircraft. 

1.2.3 Investigation Reason. 

Very little data has been generated or published indicating whether mixing wire types creates 

short- or long-term problems. Since recent Aging Transport Systems Rulemaking Advisory 

Committee aircraft inspections indicated mixed wire might be a problem [1], it was determined 

that an investigation was warranted for aged aircraft. 

2. APPROACH. 

The current requirements from various regulatory and military documents that have been used as 

guidance regarding the mixing of different wire types in electrical wiring interconnection system 

(EWIS) bundles were reviewed. Aircraft wiring practices referencing mixed wire types were 

also examined. Past test results, formal or informal, were analyzed. Based on the background 

information gathered, a test program was developed and executed to assess the actual 

1
interactions between different wire types within the same bundles or in adjacent harnesses in the 

EWIS. 

3. REVIEW OF DOCUMENTATION. 

A collection of information related to mixing of dissimilar wire types that was compiled through 

extensive research of military specifications, Federal Aviation Administration (FAA) regulations 

and advisory material, technical manuals, and other documentation are found in appendix A. It 

also summarizes the results of the search and provides a description of how, and to what extent, 

the subject is currently addressed in the aerospace industry. 

3.1 REVIEW OF REGULATIONS, PROPOSED REGULATIONS, AND DESIGN 

SPECIFICATIONS. 

FAA regulations, Title 14 Code of Federal Regulations (CFR), Airworthiness Directives, ACs, 

military and commercial design documents such as SAE AS50881 (formerly MIL-W-5088) and 

SAE ARP4404, and other documents were researched extensively for information related to the 

mixing of dissimilar wire types in bundles (as shown in appendix A). 

Two major points are evident from the research. First, there are no specific statements in any of 

the documents that specifically address how mixing of dissimilar wire types in bundles should or 

should not be performed. Second, the documents imply that mixing different wire types is not 

restricted. However, regulations do stipulate that the wire selected for an application must meet 

the environmental and application requirements demanded of the wire, wiring components 

interface requirements, and design recommendations such as minimizing the number of 

components used in the EWIS. 

3.2 AIRCRAFT WIRING PRACTICES.

3.2.1 Original Aircraft Manufacturers Wiring Practices. 

OAM standard wiring practices were reviewed to identify guidelines related to mixing wire types 

in installation, maintenance, repair, and inspection of the EWIS. The wiring practices of the 

following OAMs, as described through the standard wiring practices manuals, were reviewed for 

material related to mixing of dissimilar wire types. 

• Airbus Industrie Electrical Standard Practices Manual 

• Boeing D6-54446 Standard Wiring Practices Manual (chapter 20) 

Lockheed Martin also provided informal information but no documentation. 

Only limited relevant processes and practices of the operators and the OAMs were provided, 

making it difficult to provide a clear picture of what the current commercial practices are in 

regard to mixing different wire types within the same wire bundles during installation, repair, 

modification, and routine maintenance. 

2
It is generally accepted that the use of fewer parts on an aircraft will help to keep the overall 

costs down. The logistical costs of maintaining aircraft with multiple wire types and tooling are 

often cost prohibitive. OAMs prefer to use one wire type for all major wiring on the aircraft; 

however, special applications or environments may require that a different type of wire be used 

that can meet these special requirements. These various wire types will usually lay together in 

the same wiring runs and harnesses, or cross other wires. Since one wire length may pass 

through multiple areas of an aircraft with vastly different environmental conditions, the wire 

must be able to meet the most stringent of those application requirements. 

3.2.2 Commercial Maintenance and Operator Wiring Practices. 

Maintenance facilities and operators usually follow the instructions and recommendations of the 

OAM for a specific airframe. Some facilities attempt to decrease parts inventories through 

standard process initiatives and may substitute parts through that process. In areas where 

modifications are made to the EWIS, mixing of wire types will occur if substitute wire types are 

used. Many of the older aircraft have airframe wire that is no longer allowed in the new 14 CFR 

Part 25 aircraft and is discouraged from use in aerospace applications. When repairs are made to 

the EWIS, these wires or portions of these wires could be replaced with alternative wire types. 

3.2.3 Modification Facilities. 

Facilities that hold a Supplemental Type Certificate may perform modifications to the aircraft 

with different wire types than were originally used on the aircraft when approved by FAA 

authorities. 

3.2.4 Military Maintenance and Operation Wiring Practices. 

As with many military maintenance documents, NAVAIR 01-1A-505 and U.S. Air Force T.O. 

1-1A-14 “Installation Practice Aircraft Electric and Electronic Wiring” manuals and other 

documents (listed in appendix A) do not specify that mixing of dissimilar wire types can or 

cannot take place in the aircraft. However, there is wire substitution information contained in 

NAVAIR 01-1A-505.2 concerning wire replacement for repair and maintenance. For example, 

work package 006 contains very specific instructions for replacing M81381 aromatic polyimide 

insulated wire types with M22759 cross-linked ethylene-tetrafluoroethylene (XLETFE) insulated 

wire types for single conductor repair. For aircraft that were originally manufactured with 

polyimide insulated wires, the instructions in the work package tacitly call for an eventual 

mixing of wire types over time as old polyimide is replaced with fluorocarbon-based wire during 

maintenance and repair actions. 

The U.S. Air Force does not appear to have published policy related to specific replacement of 

wire across the board. However, specific platforms can and do make decisions, such that older 

wire types can be replaced with available alternative wire types. Over time, this will lead to the 

presence of mixed wire types in U.S. Air Force aircraft. 

The Naval Aerospace Vehicle Wiring Action Group guideline, D5-GI-1188, assists maintenance 

personnel with replacement of polyvinylchloride (PVC) and aromatic and aliphatic-type 

polyimide insulated wire types. The guidance specifies the replacement of PVC insulated wire 

3
and aromatic and aliphatic polyimide insulated wire with XLETFE insulated wire. The guideline 

also provides wire substitutions for canceled wire specifications and for certain common wire 

types stored in wiring shops. 

These directives and guidelines indicate that mixing of wire types in U.S. Navy and U.S. Air 

Force aircraft is a recognized practice that is necessary and acceptable. 

3.3 REVIEW OF SERVICE DATA. 

Review of field service data did not indicate that failures occur as a result of mixed wires. There 

were significant insulation abrasion failures reported that may or may not be attributed to mixed 

wire, but there was no indication by the repair actions that mixed wires were the issue (see 

appendix A). 

3.4 REVIEW OF PRIOR RESEARCH AND TEST DATA (INDUSTRY, GOVERNMENT, 

MILITARY, ETC.). 

Some parts of the military are presently looking at the issue of mixed wire, but the only formal 

report found is the Naval Avionic Center (NAC) report TR-2333 [2]. The results indicate that 

the dielectric characteristics of harder insulations are reduced significantly more than those of 

softer insulation types. In some cases, the withstand voltage capability was reduced nearly 50% 

from the initial values, but it should be understood that even at these reduced levels, the wire 

withstand voltage capability was still 15 times greater than the wire insulation-rated value. 

Another significant result from the report is that the withstand voltage began to level off between 

250 and 512 hours of vibration conditioning. It is unknown whether the withstand voltage would 

continue to be unchanged after 512 hours of vibration. Visual observations from the study 

indicate that the reduction in withstand voltage capability was probably due to wire-to-wire wear. 

3.5 DOCUMENTATION REVIEW SUMMARY. 

There is limited documentation in the commercial industry (OAMs, wire manufacturers, etc.), 

academia, military, and government agencies that define the current state of knowledge of the 

effects of mixed wire in the aircraft EWIS. Maintenance and service (accident/incident) reports 

examined for specific effects of the mixing of wire types yielded no data. Overall, the 

documentation indicates that it is standard practice to mix wire types in new aircraft, aged 

aircraft, and in repair actions, although the general consensus (ATSRAC WG-6 report [3]) is to 

refrain from mixing different wire types unless necessary. The review also indicates that only 

limited tests were performed to determine the long-term impact of mixing wire types in an 

aircraft. 

4. TEST PROGRAM. 

A limited test program was designed to expand on previous testing performed in this area and to 

answer a number of questions related to the effects of mixing wire types within the EWIS in an 

aircraft environment. 

4
The test program was developed from previous Raytheon testing experiences and a review of the 

test procedures from the NAC TR-2333 report and Douglas Corporation report MDC J1530/01 

[4]. Some of the fixtures and equipment from the NAC testing program were used for the test 

program. The basis of the tests was that physical interactions are accelerated by vibration of 

mixed wire bundles. The vibration causes the motion of the wires against each other to occur at 

a quick rate, accelerating the physical contact and degradation mechanisms. The mixed wire 

bundles were baselined to bundles with only one wire type. Foreign object debris and a known 

chemical were also used to simulate other aircraft environments. 

4.1 TEST PLAN. 

A test plan was established to evaluate the baseline wire bundles (one wire type) and the mixed 

wire combinations at specified intervals. The following summarizes the test plan: 

• Groups I and II 

− Baseline dry insulation resistance (500 Vdc, 1000 megohms pass/fail threshold, 1 

second dwell time) 

− Baseline dry dielectric withstand voltage (1000 Vac, 1 milliamp (mA) leakage 

current, 1 second dwell time) 

− Random vibration exposure (23.88 grms; see figure B-1 in appendix B), two or 

three subcycles: 

• Visual inspection on mounted bundles after each subcycle 

• Dry insulation resistance after each subcycle 

• Dry dielectric withstand voltage after each subcycle 

− Wet insulation resistance (500 Vdc, 1000 megohms pass/fail threshold, 1 minute 

dwell time) 

− Wet dielectric withstand voltage (1000 Vac, 1 mA leakage current, 1 minute 

dwell time) 

− Visual inspection of unassembled tested bundles 

• Group III 

− Crush test 

Group I consisted of 48 wire combinations that were subjected to a total of 500 hours of 

vibration conditioning, with the conditioning paused after 100 and 250 hours for the performance 

of visual and electrical evaluations. 

Group II was similar to group I, except only 24 of the original combinations were selected. One 

set of the 24 wire combinations was soaked in hydraulic fluid prior to vibration conditioning 

5
(group IIF), and a similar set was contaminated with metal shavings (group IIM). Since these 

bundles were contaminated, the vibration exposure was reduced to 250 hours, and a visual 

inspection was performed after 100 hours. 

Group III consisted of a crush test on the same 24 combinations as tested in group II. Single 

wires were placed perpendicular to each other, and a load was applied to determine which 

insulation exhibited the most damage. For each combination of wire selected, four tests were 

performed with a load of 80 pounds, and four tests with a load of 120 pounds. The wires were 

evaluated by quantifying the degree of permanent deformation to the insulation of each wire type 

in the pairs tested. (The complete details of the test plan are in appendix B.) 

4.2 SPECIMEN DESCRIPTION. 

The wire types chosen for this test program represent typical wire families used in aged aircraft, 

though there are various construction types within a wire family. For example, PVC/glass/nylon 

differs from PVC/nylon in that it uses glass fiber braid between the layers of insulation. Since 

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-W5086/2-22. 

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/ 

Glass 

10 

PI/PTFE 

11 

PI/PTFE 

Alloy 

The rationale for selecting the combinations for group I included: 

• Selecting a type that would give the most encompassing data when several wire types had 

similar characteristics (e.g., wire with copper alloy conductor is stiffer than wire with 

annealed copper conductor, and may lead to different results). 

• Excluding specific wire combinations that would not be expected in an application. For 

example, many of the older aircraft are wired using PVC/glass/nylon insulated wire and 

are repaired using the same wire type, but it is not typically used for modifications. Also, 

the use of PVC/glass/nylon in combination with polyimide, XPI, PTFE, or composite 

(wrapped aromatic polyimide (PI) and PTFE) insulated wire is expected to be minimal. 

• Selecting types with which aircraft are typically wired, including in specific applications 

and during modifications or repairs. For example, a combination of PVC/glass/nylon 

with the mineral-filled PTFE, which is often used as an abrasion-resistant wire 

construction in many aircraft, was included. The combination of PTFE and PI/PTFE 

composite insulated wire was excluded, since the abrasion resistance variety is more 

common. 

8
Forty-eight wire bundles were also tested in group II, but since two contamination variables 

(metal shavings and hydraulic fluid) were introduced, the number of different wire combinations 

tested for each contamination type had to be reduced to the twenty-four unshaded combinations 

shown in table 3. 

TABLE 3. WIRE COMBINATIONS TESTED IN GROUP II 

Wire 

Type 

1 

PVC/ 

G/N 

2 

PI 

3 

XPI 

Alloy 

4 

XLETFE 

7 

MFPTFE 

9 

PTFE/ 

Glass 

10 

PI/PTFE 

11 

PI/PTFE 

Alloy 

1 

PVC/ 

G/N 

2 

PI 

3 

XPI 

Alloy 

4 

XLETFE 

7 

MF-PTFE 

9 

PTFE/ 

Glass 

10 

PI/PTFE 

11 

PI/PTFE 

Alloy 

The rationale used in selecting the wire combinations for group II was similar to that used for 

group I, but also included 

• selecting the types most commonly used in aircraft applications. 

• removing XLETFE insulated copper alloy conductor wire since the difference between 

the alloy and annealed versions was evaluated in the first test group. 

• deleting combinations with the PTFE/glass fiber braid type insulated wire, except for the 

one mixed with XLETFE insulated wire. 

• removing combinations with the PI/PTFE alloy conductor wire, except for the ones with 

either XLETFE or the PI/PTFE annealed copper conductor type. 

4.5 CRUSH TEST WIRE COMBINATIONS. 

The group III crush test was performed on single wires of the same 24 combinations as shown in 

table 3. 

9
5. DISCUSSION AND RESULTS. 

Potential risks associated with simulation testing are common in most test situations. These risks 

include (1) whether the testing realistically simulates the actual conditions seen in operation, (2) 

whether there is control over as many variables as possible, and (3) the variability of test 

measurements and observations. To mitigate these risks, previous research, test data, and 

procedures were consulted prior to finalizing the test plan. For comparison, mixed wire bundles 

were tested with baseline nonmixed wire bundles. 

The primary scope of this program was to determine the impact of mixing different wire 

insulation types within the same bundle in an aircraft. The test data generated in this program 

included electrical measurements, wire-to-wire wear, wear from support components, wear from 

contaminants, and resistance to crushing. Summaries and comparisons of the test data permitted 

conclusions to be drawn as to the role the variables played in the interactions between the same 

wire and different wire types (The data generated for this test program is compiled in 

appendix C). 

5.1 GROUP I TEST RESULTS. 

5.1.1 Visual Observations on Mounted Bundles. 

Upon completion of 100, 250, and 500 hours of vibration exposure, the wire bundles were 

visually inspected while still mounted on the test fixtures. General observations after 100 hours 

of vibration included rotation of the heads of the straps; twisted pairs separating from the 

bundles; wear marks on the fixtures from wires, straps; and lacing string; and slippage of bundles 

in the cushion clamps. After 250 hours of vibration, additional observations included the 

presence of white residue from wire insulation or cushion clamp, lacing string cutting into the 

insulation, and wearing of the black wire stripe marking. The same types of conditions were 

observed after 500 hours of testing as after 250 hours, but the severity of the conditions had 

increased. (The complete results from the inspections are shown in appendix C.) 

5.1.2 Electrical Testing. 

Following 100, 250, and 500 hours of vibration exposure, the test bundles were electrically 

tested for insulation resistance (IR) and dielectric withstand voltage (DWV) in the dry condition. 

After 500 hours of vibration, the bundles were submerged in a saltwater bath for wet electrical 

testing. 

No dry IR or DWV failures were detected after 100 hours of vibration conditioning. However, 

failures were observed following 250 and 500 hours of vibration exposure. Not as many failures 

were detected during dry electrical testing as during wet testing. This might be due to the 

position of the wear on a wire, whether from other wires, support hardware, or the test fixture, 

could be such that it was isolated from other circuits. During the wet electrical testing, the 

individual wires were immersed in a saltwater bath so that the complete external surface of the 

wire could be tested for failures. For this analysis, a wire was not considered to have failed if it 

passed the DWV test, even if the IR was below the selected pass/fail threshold. No electrical 

10
failures were detected on the PVC/glass/nylon, PI, XLETFE, or PI/PTFE alloy wire types (codes 

1, 2, 4, and 11 in table 1) in either the mixed or nonmixed bundles. 

Only one dry electrical test failure was confirmed by wet electrical testing; however, all wet 

electrical failures were confirmed through visual examination of the test bundles. For this 

reason, the dry electrical results were considered suspect. Occasional DWV failures related to 

wire aging is expected. This was not considered significant unless several instances occurred in 

one bundle or moderate to severe wear was noted during visual examination. (A complete 

summary of the dry and wet IR and DWV failures is provided in appendix C, tables C-2 through 

C-4.) 

5.1.3 Wire-to-Wire Wear. 

The visual examination data from the unassembled bundles is compiled in appendix C, table C-5. 

The results are summarized by wire type in table C-6 of appendix C so that wire-to-wire wear 

data for each type, in mixed and nonmixed bundles, could be analyzed. Each column in 

table C-6 provides a comparison of the nonmixed bundle to the mixed bundle combinations 

selected. The table also identifies which bundles were slipping within the cushion clamps after 

100 hours of vibration, provides a damage rating for the wires rubbing against the fixture plate, 

and quantifies the electrical failures that were detected. 

A graphical representation of the group I wire-to-wire wear for each wire type in mixed and 

nonmixed configurations is provided in figures 1 through 10. The damage severity ratings of 0, 

1, 2, and 3 in the charts correspond to none, low, moderate, and severe ratings, respectively, and 

were assigned based upon subjective visual observations. No bars shown for a particular wire 

code indicates that the combination was not tested. 

0

1

2

3

1 2 3 4 5 6 7 9 10 11

with Wire Code

Severity of Damage (0 - 3)

Wear to wire

Wear from

clamps

wear from

plate

FIGURE 1. GROUP I TESTING: PVC/GLASS/NYLON (WIRE CODE 1) WIRE DAMAGE 

AFTER 500 HOURS OF VIBRATION CONDITIONING 

11
0

1

2

3

1 2 3 4 5 6 7 9 10 11

with Wire Code

Severity of Damage (0 - 3)

Wear to

wire

Wear from

clamps

wear from

plate

FIGURE 2. GROUP I TESTING: PI (WIRE CODE 2) WIRE DAMAGE AFTER 500 HOURS 

OF VIBRATION CONDITIONING 

0

1

2

3

1 2 3 4 5 6 7 9 10 11

with Wire Code

Severity of Damage (0 - 3)

Wear to wire

Wear from

clamps

wear from

plate

FIGURE 3. GROUP I TESTING: ALIPHATIC PI, ALLOY (WIRE CODE 3) WIRE 

DAMAGE AFTER 500 HOURS OF VIBRATION CONDITIONING 

12
0

1

2

3

1 2 3 4 5 6 7 9 10 11

with Wire Code

Severity of Damage (0 - 3)

Wear to wire

Wear from

clamps

wear from

plate

FIGURE 4. GROUP I TESTING: XLETFE (WIRE CODE 4) WIRE DAMAGE AFTER 500 

HOURS OF VIBRATION CONDITIONING 

0

1

2

3

1 2 3 4 5 6 7 9 10 11

with Wire Code

Severity of Damage (0 - 3)

Wear to wire

Wear from

clamps

wear from

plate

FIGURE 5. GROUP I TESTING: XLETFE, ALLOY (WIRE CODE 5) WIRE DAMAGE 

AFTER 500 HOURS OF VIBRATION CONDITIONING 

13
0

1

2

3

1 2 3 4 5 6 7 9 10 11

with Wire Code

Severity of Damage (0 - 3)

Wear to wire

Wear from

clamps

wear from

plate

FIGURE 6. GROUP I TESTING: PTFE (WIRE CODE 6) WIRE DAMAGE AFTER 500 

HOURS OF VIBRATION CONDITIONING 

0

1

2

3

1 2 3 4 5 6 7 9 10 11

with Wire Code

Severity of Damage (0 - 3)

Wear to wire

Wear from

clamps

wear from

plate

FIGURE 7. GROUP I TESTING: PTFE, MINERAL-FILLED (WIRE CODE 7) WIRE 

DAMAGE AFTER 500 HOURS OF VIBRATION CONDITIONING 

14
0

1

2

3

1 2 3 4 5 6 7 9 10 11

with Wire Code

Severity of Damage (0 - 3)

Wear to wire

Wear from

clamps

wear from

plate

FIGURE 8. GROUP I TESTING: PTFE/GLASS BRAID (WIRE CODE 9) WIRE DAMAGE 

AFTER 500 HOURS OF VIBRATION CONDITIONING 

0

1

2

3

1 2 3 4 5 6 7 9 10 11

with Wire Code

Severity of Damage (0 - 3)

Wear to wire

Wear from

clamps

wear from

plate

FIGURE 9. GROUP I TESTING: PI/PTFE (WIRE CODE 10) WIRE DAMAGE AFTER 500 

HOURS OF VIBRATION CONDITIONING 

15
0

1

2

3

1 2 3 4 5 6 7 9 10 11

with Wire Code

Severity of Damage (0 - 3)

Wear to

wire

Wear from

clamps

wear from

plate

FIGURE 10. GROUP I TESTING: PI/PTFE, ALLOY (WIRE CODE 11) WIRE DAMAGE 

AFTER 500 HOURS OF VIBRATION CONDITIONING 

Figure 1 indicates that negligible wire-to-wire wear occurs with PVC/glass/nylon wire, whether 

in a mixed or nonmixed bundle. 

Figure 2 indicates that PI wire consistently exhibits low wire-to-wire wear whether in a mixed or 

nonmixed bundle. 

Figure 3 indicates that XPI alloy wire exhibits moderate wire-to-wire wear in the nonmixed and 

mixed bundles, except in combinations with PTFE/glass (code 9), PI/PTFE (code 10), and 

PI/PTFE alloy (code 11), where a low amount of wear was observed. 

Figure 4 indicates that XLETFE wire has negligible wire-to-wire wear in the nonmixed and 

mixed bundles, except in combination with PVC/glass/nylon, where a low level of wear was 

noted. 

Figure 5 indicates that XLETFE alloy wire exhibits low wire-to-wire wear in the nonmixed 

bundle and in combination with PVC/glass/nylon (code 1) and PI (code 2). Negligible wear was 

observed when mixed with other wire types. 

Figure 6 indicates that PTFE wire exhibits low wire-to-wire wear when mixed with XPI wire 

(code 3), and negligible wear in all other combinations and in the nonmixed bundle. 

Figure 7 indicates that mineral-filled PTFE wire exhibits negligible or very low wire-to-wire 

wear in the nonmixed and mixed bundles. 

Figure 8 indicates that negligible wire-to-wire wear was observed on PTFE/glass wire, whether 

in mixed or nonmixed bundles. 

16
Figure 9 indicates that PI/PTFE exhibits low wire-to-wire wear when mixed with PI wire 

(code 2) only. This is likely caused by the PI insulation being more abrasive than the outer 

PTFE layer of the PI/PTFE wire. In the nonmixed bundle, and in all other combinations, 

negligible wear was observed. 

Figure 10 indicates that there was negligible wire-to-wire wear of PI/PTFE alloy in the nonmixed 

and mixed bundles. The slight difference in the results between the same insulation types in 

figures 9 and 10 may be due to the subjectivity of the visual examinations. 

Figure 11 provides a summary of five mixed wire bundle combinations in which one of the wires 

exhibited more severe wire-to-wire wear than in the nonmixed bundle. The wire types exhibiting 

more wear are XLETFE, PTFE, MF-PTFE, and PI/PTFE (codes 4, 6, 7, and 10, respectively). 

However, in these combinations, the differences in wear were slight and could be attributed to 

the subjectivity of the data. The following observations were made on these combinations: 

• 1, 4 (PVC/glass/nylon, XLETFE): The XLETFE exhibited more damage when mixed in 

a bundle with the glass fiber with nylon than in the nonmixed bundle. 

• 3, 6 and 3, 7 (XPI, PTFE and XPI, MF-PTFE): The XPI caused a little more damage on 

both of the PTFE insulated wire types in the mixed bundles, but the damage was slightly 

less on the abrasion-resistant MF-PTFE. Neither of the PTFE wire types caused 

additional damage to the XPI wire. The XPI had poor resistance to abrasion regardless of 

the other wire type. 

• 5, 7 (XLETFE alloy, MF-ETFE): The XLETFE alloy showed slightly less damage when 

mixed with MF-PTFE than in its baseline bundle, but the MF-PTFE showed slightly 

more damage in the mixed configuration. 

• 2, 10 (PI, PI/PTFE): The PI/PTFE showed a little more damage in the mixed 

configuration due to the PTFE outer coating being softer than the PI coating. 

0

1

2

3

1,4 3,6 3,7 5,7 2,10

Combinations (wire codes)

Severity of Damage (0-3)

Damage to First

Wire

Damage to Second

Wire

First Wire baseline

Second Wire

Baseline

FIGURE 11. WIRE INTERACTIONS IN GROUP I MIXED BUNDLES 

17
Overall, the results indicated that within the subjectivity of the data, wire-to-wire wear is not 

significant in mixed or nonmixed bundles on the wire types tested, with the possible exception of 

XPI wire (code 3) that exhibited moderate wear in both the mixed and nonmixed bundles (see 

figures 12 and 13). The vibration level chosen for the program is similar to the high vibration 

levels expected in U.S. Navy aircraft, so it can be presumed that at lower levels, the wear would 

be less. The vibration profile used in this test program may be different from the vibration levels 

experienced by the EWIS in commercial aircraft. 

FIGURE 12. MODERATE WIRE-TOWIRE WEAR ON GROUP I XPI IN 

BUNDLE MIXED WITH PTFE 

FIGURE 13. MODERATE WIRE-TOWIRE WEAR IN GROUP I NONMIXED 

XPI BUNDLE 

5.1.4 Wire Wear From Clamps. 

The visual examination data from the unassembled bundles are also summarized in appendix C, 

table C-6 so that the data regarding wire wear from the clamps for each wire type could be 

analyzed. Each column in table C-6 provides a comparison of the nonmixed bundle to the mixed 

bundle combinations selected. The table also indicates whether the bundle was slipping within 

the cushion clamps after 100 hours of vibration, provides a damage rating for the wires rubbing 

against the fixture plate, and quantifies the electrical failures. 

The graphical representation of the wire wear from clamps in mixed and nonmixed conditions 

for each wire type is shown in figures 1 through 10. 

Figures 1, 4, and 5 show that only the PVC/glass/nylon, XLETFE, and XLETFE alloy wire types 

(codes 1, 4, and 5, respectively) exhibited more wear from the clamps in certain mixed bundles 

than in the nonmixed bundle. It was also noted that the XPI, PTFE, MF-PTFE, PTFE/glass, 

PI/PTFE, and PI/PTFE alloy wires (codes 3, 6, 7, 9, 10, and 11) all exhibited moderate or severe 

wear from the clamps, but the wear was similar in the mixed and nonmixed bundles (see figures 

14 and 15 and additional figures D-1 through D-7 in appendix D). 

The one XPI wire that failed the wet DWV test was determined to be from a combination of 

wear from wire-to-wire interaction and wear from the clamps in the nonmixed bundle (see 

figure 14). 

18
FIGURE 14. MODERATE WIRE WEAR 

FROM CLAMPS ON NONMIXED XPI 

BUNDLE IN GROUP I 

FIGURE 15. MODERATE WIRE WEAR 

FROM CLAMP ON PI/PTFE AND 

XPI IN GROUP I 

The wire types with the most electrical failures were the PTFE/glass and PTFE (codes 9 and 6, 

respectively); however, all the failures were attributed to the severe wear from the clamps (see 

figures D-1, D-2, D-3, and D-5 in appendix D). 

The PI/PTFE wire (code 10) exhibited one DWV failure in a bundle mixed with MF-PTFE 

(code 7), which was attributed to moderate wear from the clamps (see appendix D, figure D-8) 

and wear from the vibration fixture plate. No wire-to-wire wear was evident in the bundle. 

Data was also plotted to analyze whether the clamp diameter and bundle diameter difference or 

slippage in the clamps after 100 hours of vibration exposure had a direct correlation to the 

severity of wire-to-wire or wire from clamp damage. 

Figure 16 indicates that a higher difference between the bundle and clamp diameters was not the 

only factor in determining the severity of the wire-to-wire wear. The figure also indicates that 

slipping in the clamps did not cause the wire-to-wire damage to be more severe. 

0

1

2

3

0 0.01 0.02 0.03 0.04 0.05 0.06 0.07

Clamp and bundle diameter difference (in.) 

Severity of Damage

No slippage

Slipped

FIGURE 16. GROUP I: TIGHTNESS OF CLAMP VS WEAR FROM WIRE 

19
Figure 17 indicates that a higher difference between the bundle and clamp diameters was not the 

only factor in determining the severity of the wire wear from the clamps. The figure also 

indicates that slipping in the clamps did not necessarily cause the wire wear from clamps to be 

more severe. 

0

1

2

3

0 0.01 0.02 0.03 0.04 0.05 0.06 0.07

Clamp and bundle diameter difference (in.) 

Severity of Damage

No slippage

Slipped

FIGURE 17. GROUP I: TIGHTNESS OF CLAMP VS WEAR FROM CLAMP 

These results were not expected, since it is generally an industry standard practice to tightly 

clamp wire bundles to minimize wire movement and wear from the clamps and other wires. 

More investigation is needed to determine the appropriate level of clamping required to 

minimize wire wear. 

5.1.5 Wire Wear From Straps and Lacing String. 

Visual examination results from unassembled bundles were also reviewed to determine the 

amount of damage that the wires sustained from the straps and lacing string. (A summary of the 

results is provided in appendix C, table C-5.) 

The results indicate that all the wire types displayed little or no wear at the straps, whether the 

bundles were nonmixed or mixed wire types. The PI wire (code 2) had a little wear when mixed 

with PTFE/glass (code 9), whereas there was none in the PI nonmixed bundle. The XLETFE 

alloy wire (code 5) had a little wear with the XPI, PTFE, and PI/PTFE wire type (codes 3, 6, and 

10, respectively), but none in the nonmixed. The PI/PTFE wire (code 10) had a little wear with 

the XPI, XLETFE, XLETFE alloy, and MF-PTFE wire types (codes 3, 4, 5, and 7,respectively), 

but none in the nonmixed. 

Only the PI, MF-PTFE, and PI/PTFE alloy wire types (codes 2, 7, and 11, respectively) showed 

any wear from the lacing string, and this was just in one case each in a mixed wire bundle. 

Overall, within the subjectivity of the visual examinations performed, the results indicate no 

significant wire wear occurred from the straps or lacing string in group I. 

20
5.1.6 Wire Wear From Vibration Fixture Plate. 

A number of wire types suffered abrasion from the aluminum test fixture during vibration, which 

may have contributed to electrical failures. Figures 1 through 10 provide a graphical 

representation of the wire wear from the plate for each wire type in the mixed and nonmixed 

configurations. 

The two electrical failures detected on the XLETFE alloy wire (code 5) in the nonmixed bundle 

were attributed to the severe wire wear from rubbing against the vibration fixture (see appendix 

D, figure D-9). A little wire-to-wire wear was also observed on this wire type in the nonmixed 

configuration. 

One electrical failure was also detected on the XLETFE alloy wire (code 5) in a bundle mixed 

with MF-PTFE (code 7), but visual examination of the bundle indicated that the failure was 

caused by wire wear from the plate or clamps since no wire-to-wire wear was noted. 

5.1.7 Wear of Support Components. 

The clamps were the only support components (clamps, straps, and lacing string) that exhibited 

moderate wear. In these cases, either PVC/glass/nylon or PTFE/glass wires were in the bundles 

(see figures 18 and 19). This might be explained by the abrasive nature of the glass component 

within the PTFE/glass insulation and the slightly harder outer coating of the PVC/glass/nylon 

wire. 

FIGURE 18. MODERATE WEAR ON 

CLAMP FROM PVC/GLASS/NYLON 

AND MF-PTFE GROUP I BUNDLE 

FIGURE 19. MODERATE WEAR OF 

CLAMP FROM NONMIXED 

PTFE/GLASS BUNDLE IN GROUP I 

5.1.8 Wear of Single Wires vs Twisted Pairs. 

It was noted that nearly twice as many wet electrical failures were detected on twisted pairs than 

single wires in group I. This was likely due to the high points of the twisted pairs being 

subjected to concentrated frictional forces from wires rubbing against each other. 

21
5.2 GROUP II TEST RESULTS. 

5.2.1 Visual Observations. 

Upon completion of 100 and 250 hours of vibration exposure, the wire bundles were visually 

inspected while still mounted on the test fixtures. General observations after 100 hours of 

vibration included rotation of the heads of the straps; twisted pairs separating from the bundles; 

wear marks on the fixtures from wires, straps, and lacing string; the presence of residue on the 

bundles from the clamp or wire insulation; slippage of bundles in the cushion clamps; and 

splatter marks on bundles from the fluid contamination. After 250 hours of vibration, additional 

observations included lacing string cutting into insulation and wearing of the black wire stripe 

marking. The results from the inspection are shown in appendix C, table C-7. 

5.2.2 Electrical Testing. 

No dry insulation resistance or DWV failures were detected after 100 hours of vibration 

conditioning in group II. Furthermore, no dry DWV failures were observed following 250 hours 

of vibration exposure. However, some wires failed to meet the IR pass/fail threshold selected for 

the program. As in group I, a wire was not considered to have failed if it passed the DWV test, 

even if IR did not exceed the selected pass/fail threshold. Electrical failures were detected on the 

PTFE/glass and PI/PTFE wires only (codes 7 and 10, respectively). (A complete summary of the 

dry and wet IR and DWV failures is provided in appendix C, tables C-8 and C-9. Specific 

electrical failures are discussed in conjunction with the wire wear paragraphs.) 

Only one dry DWV test failure was confirmed by wet testing; however, all wet DWV failures 

were confirmed through visual examination of the test bundles. For this reason, the dry electrical 

results are considered suspect. 

5.2.3 Wire-to-Wire Wear. 

The visual examination results of the group II unassembled bundles are compiled in appendix C, 

tables C-10 and C-11. The results are summarized in table C-12 so that the wire-to-wire wear 

data for each type, mixed and unmixed, could be analyzed and the different wire types could be 

compared. Each column in table C-12 provides a comparison of the nonmixed bundle to the 

mixed bundle combinations selected. The table also indicates whether the bundle was slipping 

within the cushion clamps after 100 hours of vibration, provides a damage rating for the wires 

rubbing against the fixture plate, and quantifies the electrical failures that were detected. 

5.2.3.1 Group IIF Fluid-Soaked Bundles. 

Figures 20 through 27 provide graphic representations of the wire-to-wire wear for each wire 

type in mixed and nonmixed bundles. 

Figure 20 indicates that negligible wire-to-wire wear occurs with PVC/glass/nylon wire, whether 

in a mixed or nonmixed bundle. 

22
0

1

2

3

1 2 3 4 5 6 7 9 10 11

with Wire Code

Severity of Damage (0 - 3)

Wear to wire

Wear from

clamps

wear from

plate

FIGURE 20. GROUP IIF TESTING: PVC/GLASS/NYLON (WIRE CODE 1) WIRE 

DAMAGE AFTER 250 HOURS OF VIBRATION CONDITIONING 

0

1

2

3

1 2 3 4 5 6 7 9 10 11

with Wire Code

Severity of Damage (0 - 3)

Wear to wire

Wear from

clamps

wear from

plate

FIGURE 21. GROUP IIF TESTING: PI (WIRE CODE 2) WIRE DAMAGE AFTER 250 

HOURS OF VIBRATION CONDITIONING 

23
0

1

2

3

1 2 3 4 5 6 7 9 10 11

with Wire Code

Severity of Damage (0 - 3)

Wear to wire

Wear from

clamps

wear from

plate

FIGURE 22. GROUP IIF TESTING: ALIPHATIC PI, ALLOY (WIRE CODE 3) WIRE 

DAMAGE AFTER 250 HOURS OF VIBRATION CONDITIONING 

0

1

2

3

1 2 3 4 5 6 7 9 10 11

with Wire Code

Severity of Damage (0 - 3)

Wear to

wire

Wear from

clamps

wear from

plate

FIGURE 23. GROUP IIF TESTING: XLETFE (WIRE CODE 4) WIRE DAMAGE AFTER 

250 HOURS OF VIBRATION CONDITIONING 

24
0

1

2

3

1 2 3 4 5 6 7 9 10 11

with Wire Code

Severity of Damage (0 - 3)

Wear to

wire

Wear from

clamps

wear from

plate

FIGURE 24. GROUP IIF TESTING: PTFE, MINERAL-FILLED (WIRE CODE 7) WIRE 

DAMAGE AFTER 250 HOURS OF VIBRATION CONDITIONING 

0

1

2

3

1 2 3 4 5 6 7 9 10 11

with Wire Code

Severity of Damage (0 - 3)

Wear to

wire

Wear from

clamps

wear from

plate

FIGURE 25. GROUP IIF TESTING: PTFE/GLASS BRAID (WIRE CODE 9) WIRE 

DAMAGE AFTER 250 HOURS OF VIBRATION CONDITIONING 

25
0

1

2

3

1 2 3 4 5 6 7 9 10 11

with Wire Code

Severity of Damage (0 - 3)

Wear to

wire

Wear from

clamps

wear from

plate

FIGURE 26. GROUP IIF TESTING: PI/PTFE (WIRE CODE 10) WIRE DAMAGE AFTER 

250 HOURS OF VIBRATION CONDITIONING 

0

1

2

3

1 2 3 4 5 6 7 9 10 11

with Wire Code

Severity of Damage (0 - 3)

Wear to wire

Wear from

clamps

wear from

plate

FIGURE 27. GROUP IIF TESTING: PI/PTFE, ALLOY (WIRE CODE 11) WIRE DAMAGE 

AFTER 250 HOURS OF VIBRATION CONDITIONING 

26
Figure 21 indicates moderate wire-to-wire wear of PI wire in the nonmixed bundle and moderate 

or low wear in the mixed bundles. 

Figure 22 indicates that XPI wire exhibits low wire-to-wire wear in all combinations except with 

XLETFE (code 4), in which case, the wear is moderate. 

Figure 23 indicates that negligible wire-to-wire wear was observed on XLETFE wire in the 

nonmixed and mixed bundles. 

Figure 24 indicates that MF-PTFE wire exhibits negligible wire-to-wire wear in the nonmixed 

bundle, but slightly more wear when mixed with PVC/glass/nylon (code 1), PI (code 2), or 

PI/PTFE wire (code 10). 

Figure 25 indicates that PTFE/glass wire exhibits moderate wire-to-wire wear in the nonmixed 

condition, but low or negligible wear in the other combinations tested. 

Figure 26 indicates that negligible wear was observed in the PI/PTFE nonmixed bundle, and low 

wear when mixed with XPI (code 3) or PI/PTFE (code 10) wire. 

Figure 27 indicates that PI/PTFE alloy wire has negligible wire-to-wire wear in the nonmixed 

bundle, but slightly more when mixed with XLETFE or PI/PTFE. 

Figure 28 provides a summary of seven mixed wire bundle combinations from Group IIF in 

which at least one of the wires exhibited more severe wire-to-wire wear than in the nonmixed 

bundle. These wire types are XPI, MF-PTFE, PI/PTFE, and PI/PTFE alloy wire types (codes 3, 

7, 10, and 11, respectively). The wear on the XPI wire type (code 3) was moderate when mixed 

with XLETFE (code 4) (see figure D-10 in appendix D) compared to a low amount of wear in 

the nonmixed bundle. The wear on the MF-PTFE, PI/PTFE, and PI/PTFE alloy wires was low in 

both the mixed and nonmixed conditions. These combinations are discussed below. 

• 3, 4 (XPI, XLETFE): XPI is slightly more damaged in the mixed configuration than in 

the baseline bundle. 

• 1, 7 (PVC/glass/nylon, MF-PTFE): Both wires showed very little damage, but the MFPTFE had slightly more damage in the mixed bundle. 

• 2, 7 (PI, MF-PTFE): MF-PTFE is damage more than in its baseline, but the damage 

rating on the PI is higher for both the mixed and nonmixed bundles. 

• 7, 10 (MF-PTFE, PI/PTFE): Both wires showed very little damage, but the MF-PTFE 

had slightly more damage in the mixed bundle. 

• 3, 10 (XPI, PI/PTFE): XPI in the mixed configuration exhibited slightly less damage 

than in the nonmixed bundle, but PI/PTFE suffered slightly more than in the nonmixed 

bundle. 

27
• 4, 11 (XLETFE, PI/PTFE alloy): Both wires showed very little damage, but the PI/PTFE 

alloy had slightly more damage in the mixed bundle. 

• 10, 11 (PI/PTFE, PI/PTFE alloy): Both wire types showed a slight increase in the 

damage when mixed together. When compared to each other, the two wire types showed 

similar wear, whether in the mixed or nonmixed bundles. 

0

1

2

3

4,3 1,7 2,7 10,7 3,10 4,11 10,11

Combinations (wire codes)

Severity of Damage (0-3)

Damage to First

Wire

Damage to Second

Wire

First Wire baseline

Second Wire

Baseline

FIGURE 28. WIRE INTERACTIONS IN GROUP IIF MIXED BUNDLES 

Overall, PI, XPI, and PTFE/glass wire types (codes 2, 3, and 9, respectively) exhibited moderate 

wear on the bundles soaked in hydraulic fluid, but the wear was similar or less severe in the 

mixed bundle than in the nonmixed bundle for PI and PTFE/glass wires (see figures 21, 25, 29, 

and 30, and figure D-11 in appendix D). The wear on the XPI wire in the bundle with XLETFE 

was slightly worse than in the nonmixed bundle (see figure 22). 

FIGURE 29. MODERATE WIRE-TOWIRE WEAR IN GROUP IIF 

NONMIXED PI BUNDLE 

FIGURE 30. MODERATE WIRE-TOWIRE WEAR ON PI WHEN MIXED 

WITH MF-PTFE IN GROUP IIF 

28
5.2.3.2 Group IIM Metal Shavings Bundles. 

For the bundles containing metal shavings, figures 31 through 38 provide graphical 

representations of the wire-to-wire wear for each wire type when mixed with other types. 

0

1

2

3

1 2 3 4 5 6 7 9 10 11

with Wire Code

Severity of Damage (0 - 3)

Wear to wire

Wear from

clamps

wear from

plate

FIGURE 31. GROUP IIM TESTING: PVC/GLASS/NYLON (WIRE CODE 1) WIRE 

DAMAGE AFTER 250 HOURS OF VIBRATION CONDITIONING 

0

1

2

3

1 2 3 4 5 6 7 9 10 11

with Wire Code

Severity of Damage (0 - 3)

Wear to wire

Wear from

clamps

wear from

plate

FIGURE 32. GROUP IIM TESTING: PI (WIRE CODE 2) WIRE DAMAGE AFTER 250 

HOURS OF VIBRATION CONDITIONING 

29
0

1

2

3

1 2 3 4 5 6 7 9 10 11

with Wire Code

Severity of Damage (0 - 3)

Wear to

wire

Wear from

clamps

wear from

plate

FIGURE 33. GROUP IIM TESTING: ALIPHATIC PI, ALLOY (WIRE CODE 3) WIRE 

DAMAGE AFTER 250 HOURS OF VIBRATION CONDITIONING 

0

1

2

3

1 2 3 4 5 6 7 9 10 11

with Wire Code

Severity of Damage (0 - 3)

Wear to

wire

Wear from

clamps

wear from

plate

FIGURE 34. GROUP IIM TESTING: XLETFE (WIRE CODE 4) WIRE DAMAGE AFTER 

250 HOURS OF VIBRATION CONDITIONING 

30
0

1

2

3

1 2 3 4 5 6 7 9 10 11

with Wire Code

Severity of Damage (0 - 3)

Wear to

wire

Wear from

clamps

wear from

plate

FIGURE 35. GROUP IIM TESTING: PTFE, MINERAL-FILLED (WIRE CODE 7) WIRE 

DAMAGE AFTER 250 HOURS OF VIBRATION CONDITIONING 

0

1

2

3

1 2 3 4 5 6 7 9 10 11

with Wire Code

Severity of Damage (0 - 3)

Wear to wire

Wear from

clamps

wear from

plate

FIGURE 36. GROUP IIM TESTING: PTFE/GLASS BRAID (WIRE CODE 9) WIRE 

DAMAGE AFTER 250 HOURS OF VIBRATION CONDITIONING 

31
0

1

2

3

1 2 3 4 5 6 7 9 10 11

with Wire Code

Severity of Damage (0 - 3)

Wear to

wire

Wear from

clamps

wear from

plate

FIGURE 37. GROUP IIM TESTING: PI/PTFE (WIRE CODE 10) WIRE DAMAGE AFTER 

250 HOURS OF VIBRATION CONDITIONING 

0

1

2

3

1 2 3 4 5 6 7 9 10 11

with Wire Code

Severity of Damage (0 - 3)

Wear to

wire

Wear from

clamps

wear from

plate

FIGURE 38. GROUP IIM TESTING: PI/PTFE, ALLOY (WIRE CODE 11) WIRE DAMAGE 

AFTER 250 HOURS OF VIBRATION CONDITIONING 

Figure 31 indicates that PVC/glass/nylon exhibits very low wire-to-wire wear, whether in a 

nonmixed or mixed bundle. 

Figure 32 indicates that PI wire exhibits low wire-to-wire wear in the nonmixed and mixed 

bundle conditions. 

32
Figure 33 indicates that the XPI wire exhibits moderate wire-to-wire wear in the nonmixed 

condition, but less wear in combination with other wire types. 

Figure 34 indicates that low wire-to-wire wear was observed on XLETFE wire when mixed with 

the PI/PTFE wire types (codes 10 and 11), but slight or negligible wear was noted in 

combination with other wire types and in the nonmixed bundle. 

Figure 35 indicates that MF-PTFE wire exhibits low wear in both the mixed and nonmixed 

bundles. 

Figure 36 indicates that PTFE/glass wire consistently exhibits low wear in both the mixed and 

nonmixed bundles. 

Figure 37 indicates that the wire-to-wire wear of PI/PTFE wire is very low or negligible in all 

bundles. 

Figure 38 indicates that the wear of PI/PTFE wire is low when mixed with XLETFE (code 4), 

but negligible or very low in other combinations tested. 

Figure 39 provides a summary of six mixed wire bundle combinations from Group IIM in which 

one or both of the wire types exhibited more severe wire-to-wire wear than in the nonmixed 

bundle. Although the level of damage of one or both wire types in these combinations was 

worse in the mixed bundle than in the nonmixed bundle, the overall level was of damage was 

low. These combinations are discussed below. 

• 1, 4 (PVC/glass/nylon, XLETFE): XLETFE was adversely affected by the harder 

PVC/glass/nylon wire, but the damage was only slightly worse than in the nonmixed 

bundle. 

• 3, 4 (XPI, XLETFE): XLETFE exhibited only slightly more damage when mixed with 

XPI than in its baseline bundle. The XPI exhibited a lower level damage in this mixed 

bundle than in the baseline bundle. 

• 7, 4 (MF-PTFE, XLETFE): XLETFE exhibited slightly more damage when mixed with 

MF-PTFE than in its baseline bundle. The MF-PTFE showed a similar level of damage 

in both the nonmixed bundle and this mixed combination. 

• 9, 4 (PTFE/glass, XLETFE): The XLETFE reacted similarly with PTFE/glass as it did 

with MF-PTFE and PVC/glass/nylon. 

• 10, 4 and 11, 4 (PI/PTFE, XLETFE and PI/PTFE alloy, XLETFE): The XLETFE had 

slightly more wear when mixed with either PI/PTFE wire type than in the baseline 

bundle. The PI/PTFE alloy was damaged slightly more than in the baseline bundle. The 

alloy wire was damaged slightly more by the XLETFE than was the annealed copper 

conductor wire. 

33
• 10, 11 (PI/PTFE, PI/PTFE alloy): The alloy conductor wire was damage slightly more 

when mixed with annealed copper conductor wire than in the baseline, but the annealed 

copper conductor wire exhibited a similar level of damage. 

0

1

2

3

1, 4 3,4 7,4 9,4 10,4 11,4 10,11

Combinations (wire codes)

Severity of Damage (0-3)

Damage to First

Wire

Damage to Second

Wire

First Wire baseline

Second Wire

Baseline

FIGURE 39. WIRE INTERACTIONS IN GROUP IIM MIXED BUNDLES 

Overall, only the XLETFE (code 4) and PI/PTFE alloy (code 11) wire types exhibited more wear 

in mixed bundles contaminated with metal than in nonmixed bundles (see figures 34 and 38), but 

even then the amount of wear was slight. In addition, the XPI wire (code 3) was the only 

nonmixed bundle that exhibited moderate wire-to-wire wear in the metal contaminated bundles 

(see figures 33 and 40). The same wire type showed little wear in the mixed configurations. 

FIGURE 40. MODERATE WIRE-TO-WIRE WEAR ON XPI IN NONMIXED 

GROUP IIM BUNDLE 

34
5.2.4 Wire Wear From Clamps. 

The visual examination results from the unassembled bundles were also summarized in 

appendix C, table C-12 so that the data regarding wire wear from the clamps could be analyzed. 

Each column in table C-12 provides a comparison of the nonmixed bundle to the mixed bundle 

combinations selected. The table also indicates whether the bundle was slipping within the 

cushion clamps after 100 hours of vibration, provides a damage rating for the wires rubbing 

against the fixture plate, and quantifies the electrical failures that were noted. 

5.2.4.1 Group IIF Fluid-Soaked Bundles. 

The only electrical failures detected in a fluid-contaminated bundle were on PI/PTFE wires 

(code 10) that were mixed with XPI wires (code 3). Although a little wire-to-wire and wire-tofixture plate wear was noted, the failures were attributed to the severe wear from the clamps, as 

shown in figure 41. 

FIGURE 41. SEVERE WEAR ON PI/PTFE FROM CLAMP WHEN MIXED WITH 

XPI IN GROUP IIF 

The XPI, XLETFE, PI/PTFE, and PI/PTFE alloy wire types (codes 3, 4, 10, and 11, respectively) 

each exhibited more wear from clamps in mixed wire bundles than in the associated nonmixed 

wire bundle. The XPI wire type exhibited moderate wear from clamps when mixed with 

XLETFE, as opposed to a little wear in the nonmixed configuration. 

Data was plotted to analyze whether the clamp diameter and bundle diameter difference or 

slippage in the clamps that was documented after 100 hours of vibration exposure had a direct 

correlation to the severity of wire-to-wire or wire-from-clamp damage. 

Figure 42 indicates that a higher difference between the bundle and clamp diameters was not the 

only factor in determining the severity of the wire-to-wire wear in Group IIF, but it does 

correlate somewhat. The figure also indicates that slipping in the clamps did not necessarily 

cause the wire-to-wire damage to be more severe. The wire type was probably a factor as well. 

Figure 43 indicates that a higher difference between the bundle and clamp diameters was not the 

only factor in determining the severity of the wire wear from the clamps in Group IIF. The 

35
figure also indicates that slipping in the clamps did not necessarily cause the wire wear from 

clamps to be more severe. 

0

1

2

3

0 0.01 0.02 0.03 0.04 0.05 0.06 0.07

Clamp and bundle diameter difference (in.) 

Severity of Damage

No slippage

Slipped

FIGURE 42. GROUP IIF: TIGHTNESS OF CLAMP VS WEAR FROM WIRE 

0

1

2

3

0 0.01 0.02 0.03 0.04 0.05 0.06 0.07

Clamp and bundle diameter difference (in.) 

Severity of Damage

No slippage

Slipped

FIGURE 43. GROUP IIF: TIGHTNESS OF CLAMP VS WIRE WEAR FROM CLAMP 

5.2.4.2 Group IIM Metal Shavings Bundles. 

The only wet electrical failures on the bundles contaminated with the metal shavings were on a 

nonmixed bundle of PTFE/glass wires (code 9). This bundle exhibited severe wear from the 

clamps (see figure 44), and showed signs of a little wear from the vibration plate and wire-towire interaction. 

36
FIGURE 44. SEVERE WEAR OF PTFE/GLASS WIRE FROM CLAMP IN GROUP IIM 

NONMIXED BUNDLE 

Data was plotted to analyze whether the clamp diameter and bundle diameter difference, or 

slippage in the clamps that was documented after 100 hours of vibration exposure, had a direct 

correlation to the severity of wire-to-wire or wire from clamp damage in group II. 

Figures 45 and 46 indicate that for the wire bundles that did not slip within the clamps, the 

severity of the wire damage increased as the difference between the clamp and bundle diameters 

increased. However, the figures did not show the same direct correlation for the bundles that did 

slip in the clamps. 

0

1

2

3

0 0.01 0.02 0.03 0.04 0.05 0.06 0.07

Clamp and bundle diameter difference (in.) 

Severity of Damage

No slippage

Slipped

FIGURE 45. GROUP IIM: TIGHTNESS OF CLAMP VS WEAR FROM WIRE 

37
0

1

2

3

0 0.01 0.02 0.03 0.04 0.05 0.06 0.07

Clamp and bundle diameter difference (in.) 

Severity of Damage

No slippage

Slipped

FIGURE 46. GROUP IIM: TIGHTNESS OF CLAMP VS WIRE WEAR FROM CLAMP 

5.2.5 Wire Wear From Straps and Lacing String.

Posttest visual examination results were also reviewed to determine the amount of damage that 

the wires sustained from the straps and lacing string. A summary of the results is provided in 

appendix C, tables C-10 and C-11 and are discussed in the following sections. 

5.2.5.1 Wear From Straps. 

5.2.5.1.1 Group IIF. 

Appendix C, table C-10 visual inspection results from the unassembled bundles indicate that the 

PI, XPI, and PI/PTFE wires (codes 2, 3, and 10, respectively) were the only types to display 

moderate wear from straps in mixed wire bundles that had been soaked in hydraulic fluid (see 

figures 47 and 48). The PI wire also exhibited moderate wear in the nonmixed bundle. All the 

other types displayed little or no wear at the straps in mixed and nonmixed bundles. 

XPI wires (code 3) showed no wear from straps in the nonmixed bundle, but did show a little or 

moderate wear when mixed in bundles with PI, MF-PTFE, and PI/PTFE (see figure 47). 

PI/PTFE wires (code 10) showed less wear in the nonmixed bundle than in bundles mixed with 

XPI and MF-PTFE (see figures 47 and 48). 

38
FIGURE 47. MODERATE WEAR OF XPI 

AND PI/PTFE FROM STRAP IN 

GROUP IIF 

FIGURE 48. MODERATE WEAR OF 

PI/PTFE FROM STRAP WHEN MIXED 

WITH MF-PTFE IN GROUP IIF 

5.2.5.1.2 Group IIM. 

Table C-11 in appendix C shows that none of the bundles with metal shavings exhibited 

moderate or severe wear from the straps. Only the PI/PTFE wire (code 10) had slightly more 

wear when mixed with PI, XPI, XLETFE, MF-PTFE, and PTFE/glass (codes 2, 3, 4, 7, and 9, 

respectively) than in the nonmixed condition. 

5.2.5.2 Wear From Lacing String. 

5.2.5.2.1 Group IIF. 

Of the fluid-soaked bundles, only the PI wires (code 2) exhibited wear from the lacing string (see 

figure 49 and appendix C, table C-12). A little wear was noted for the nonmixed bundle, 

whereas moderate wear was noted when mixed with MF-PTFE. 

5.2.5.2.2 Group IIM. 

Of the metal contaminated bundles, the MF-PTFE wires (code 7) were the only ones that showed 

slight wear from the lacing string. The metal shavings themselves may have induced this wear 

by lodging between the wire and string. 

5.2.6 Wire Wear From Vibration Fixture. 

One PI/PTFE wire (code 10), in a bundle mixed with PI/PTFE alloy wire (code 11) and 

contaminated with metal shavings, failed wet electrical testing. This bundle did exhibit some 

wear from the plate, and some wire-to-wire wear, but the cause of the failure could not be 

determined. A small mark, possibly a burn mark, was noted in an area that was inside a clamp, 

so it is possible that a metal shaving penetrated the insulation, weakening the insulation system. 

39
FIGURE 49. MODERATE WEAR ON PI FROM LACING STRING WHEN MIXED 

WITH MF-PTFE IN GROUP IIF 

5.2.7 Wear on Support Components. 

The clamps were the only support components that exhibited wear with a moderate or severe 

rating, and in all but one case, one of the wire types was PVC/glass/nylon, MF-PTFE, or 

PTFE/glass. The one case that did not include one of those wire types was the nonmixed bundle 

of PI/PTFE alloy wires, which caused severe damage to the clamp. 

The straps exhibited only slight wear from several of the wire combinations, but the lacing string 

did not appear to cause wear on any of the wires in the bundles. 

5.2.8 Wear of Single Wires Versus Twisted Pairs. 

It was noted that the same number of wet electrical failures were detected on twisted pairs as on 

single wires in group II. 

5.3 TEST GROUPS I AND II COMPARISON. 

The results indicate that in the mixed wire bundles, moderate wire-to-wire wear occurred on 

more bundles contaminated with hydraulic fluid than with metal shavings. This condition was 

most pronounced on the PI and XPI wire types (codes 2 and 3, respectively). One explanation 

for this may be that many of the metal shavings in the unrestricted sections of the bundles fell out 

of the bundles during vibration conditioning. Another explanation may be that in the areas of the 

clamps, tie straps, and lacing string, the wires were restricted enough to prevent significant 

movement and interaction of the wires against the metal shavings. Still another could be that the 

hydraulic fluid, by swelling the insulation surface and softening the insulation, thereby reduced 

the resistance to abrasive forces during vibration. 

Some wire combinations in groups II exhibited slipping in clamps after 100 hours of vibration, 

whereas no slipping was noted for the same combinations in group I after the same vibration 

conditioning. 

40
The number of mixed wire bundles that showed more damage than the associated baseline 

bundles was greater in groups II than in group I; however, most of the combinations displaying 

this characteristic were different in groups I and II. There was more similarity between groups 

IIF and IIM. 

Seventy-seven percent of the group I bundles did not slip in the clamps after 100 hours of 

vibration exposure, whereas the numbers for groups IIM and IIF were 38% and 25%, 

respectively. 

In both groups I and II, the sections of the wire bundles that were mounted to stationary plates 

did not exhibit notable wire or clamp damage. 

5.4 GROUP III CRUSH TEST RESULTS. 

The crush test performed was a variation to the dynamic cut-through test that is define in SAE 

AS4373, method 703 [5]. In this crush test, a defined load was applied to compress two 

perpendicular wires, rather than compressing a blade against a single wire. The hardness of the 

second wire directly affects the amount of damage suffered by the first wire. 

The testing was performed on the same 24 wire combinations as selected for group II. The 

complete results from the test are provided in appendix C, table C-13. 

The results indicate that for the wire combinations tested, the MF-PTFE wire (code 7) always 

had the most damage in the pairs, and the PVC/glass/nylon, PI, and PTFE/glass wires (codes 1, 

2, and 9, respectively) always had the least damage. It should be noted, however, that the 

PVC/glass/nylon and PTFE/glass were only tested in two mixed combinations each. The glass 

fiber braid has an extremely high modulus and provides protection against this type of force. 

The glass fiber braid even provides protection when a blade is used in the standard dynamic cutthrough test method. 

In certain pairings, the XPI, MF-PTFE, PI/PTFE, and PI/PTFE alloy wires (codes 3, 7, 10, and 

11, respectively) each showed damage through the insulation, exposing the conductor, when 

using the 80-pound load (see figures 50 and 51 and figures D-12 and D-13 in appendix D). 

When the load was increased to 120 pounds, the XLETFE wire (code 4) also exhibited damage 

through the insulation to the conductor (see figure 52). The most severe damage was seen in the 

pairing of PI/PTFE alloy wire with itself (see figure 53). The alloy conductor is harder than the 

annealed copper conductor, and does not deform as easily, causing an increase in damage to the 

insulation. 

The crush test was not performed at elevated temperature or after a heat aging test. Two 

scenarios where an elevated temperature may be a problem are (1) when a substitute wire has a 

lower or higher temperature rating and (2) blocking to a lower temperature-rated wire would 

decrease flexibility. 

41
FIGURE 50. MF-PTFE WIRE 

DAMAGED FROM PI WIRE IN THE 

80-POUND CRUSH TEST 

FIGURE 51. PI/PTFE ALLOY WIRE 

DAMAGED FROM PI/PTFE WIRE IN 

THE 80-POUND CRUSH TEST 

FIGURE 52. XLETFE WIRE 

DAMAGED BY PI WIRE IN THE 

120-POUND CRUSH TEST 

FIGURE 53. PI/PTFE ALLOY WIRE 

DAMAGED BY SAME WIRE TYPE IN 

THE 120-POUND CRUSH TEST 

5.5 COMPARISON TO PREVIOUS DATA. 

Whereas the NAC TR-2333 program used reduction in voltage capability as a parameter for 

evaluating the wires, this program selected a DWV pass/fail threshold, so electrical testing 

results could not be directly compared. This program also used visual examinations as the 

primary tool for determining the severity of wear to the wires or support components. 

42
6. SUMMARY AND RECOMMENDATIONS.

6.1 SUMMARY.

None of the documents reviewed specifically addressed or restricted mixing of dissimilar wire 

types in bundles, but regulations stipulated that the wires selected must meet the environmental, 

application, interface, and design requirements. The results indicated that there is not 

significantly more insulation wear in mixed wire bundles than in nonmixed wire bundles. The 

results of this program did not corroborate the general finding of the Naval Avionics Center TR2333. Since the two test programs did evaluate different insulation types, a direct comparison 

could not be made. 

None of the electrical failures were attributed to the mixing of wire types in the bundles. All 

failures were due to damage caused by rubbing against the plate or movement in the clamps 

during vibration. The fluids and metal shavings appeared to have some impact on the wire-towire wear. For most wire types, hydraulic fluid and particulate contamination promoted wear of 

the wires. No significant difference was noted when comparing results from annealed copper 

conductor and copper alloy conductor wires with the same insulation type. 

Softer insulation types suffered more damage in the crush test; however, wire with harder copper 

alloy conductors exhibited greater damage than wire with softer annealed copper conductor wires 

of the same insulation type. Cross-linked aliphatic polyimide wire exhibited significant levels of 

wire-to-wire wear in mixed and nonmixed bundles and in contaminated and uncontaminated 

bundles. Polyimide and polytetrafluoroethylene glass wires exhibited significant wire-to-wire 

wear in nonmixed, fluid-contaminated bundles. Polyimide wires were the only types that 

exhibited some wire-to-wire damage in all uncontaminated combinations. 

More damage was caused by straps than by lacing string in the contaminated bundles. There was 

little damage from straps or clamps on uncontaminated bundles. No significant differences in 

wire-to-wire wear or from clamp wear was noted when comparing the curved end of the bundle 

to the straight end configuration. More damage to adjacent wires was caused by twisted pairs of 

wires than by single-end wires. 

6.2 RECOMMENDATIONS.

Special precautions need to be considered when using many wire types (XPI, soft exterior types 

such as PTFE, MF-PTFE, and PI/PTFE, and glass braid covered types such as PTFE/glass) to 

prevent wear from clamps or from the structure. Frequent maintenance inspection schedules 

should be considered for aged aircraft if these precautions have not been taken. 

Current clamping practices should be evaluated and alternative methods investigated to minimize 

damage to wire in aerospace applications. 

Routine inspection schedules for aged aircraft should include wire-to-wire wear inspections for 

XPI wire. In addition, PI and PTFE/glass wire types should be routinely inspected for wire-towire wear in fluid-contaminated areas. 

43
Routine inspection schedules for aged aircraft should include clamp to wire tightness 

inspections. Building up bundles to the clamp diameter should be considered as needed. 

The following additional testing options should be considered to further understand the 

degradation characteristics of mixed wire in the EWIS: 

• Subject test bundles to both fluid and metal shavings contamination 

• Test bundles with and without twisted pairs 

• Actively monitor during vibration testing 

• Use tape wrap inside the cushion clamp if it does not fit snugly on the wire bundle 

• Heat aging of wires prior to testing 

• Crush test at elevated temperature 

• Abrasion cut through testing 

• Flex bending of bundles 

• Alternative clamping practices 

7. RELATED DOCUMENTATION. 

a. Industry Standards 

• AS50881, SAE Aerospace Standard, Wiring, Aerospace Vehicle 

• AS22759, SAE Aerospace Standard, Wire, Electrical, Fluoropolymer-Insulated, 

Copper or Copper Alloy 

• AC 43.13-1B, Department of Transportation, Federal Aviation Administration, 

Advisory Circular: Acceptable Methods, Techniques, and Practices. Aircraft 

Inspection and Repair 

• ANM-01-04, Department for Transportation, Federal Aviation Administration, 

Policy Statement, System Wiring Policy for Certification of 14 CFR Part 25 

Airplanes 

• Advancement Handbook for Aviation Electricians Mate of 15 October 2001 

• SAE ARP4404A, Aerospace Recommended Practice, Aircraft Electrical 

Installation 

• 14 CFR Part 25, Department of Transportation, Federal Aviation Administration 

• SAE AS4373, Test Methods for Insulated Electric Wire 

b. Military Standards 

• MIL-W-81044, Military Specification, Wire, Electric, Crosslinked Polyalkene, 

Crosslinked Alkene-Imide Polymer, or Polyarylene Insulated, Copper or Copper 

Alloy 

44
• MIL-W-5086, Military Specification, Wire, Electric, Polyvinyl Chloride 

Insulated, Copper or Copper Alloy 

• ITSS (MATMEP) F/A-18 Duty Area (MOS 6337), Aircraft Electrical Technician 

• MIL-HDBK-5400, Electronic Equipment, Aerospace, General Specification For 

• MIL-HDBK-454, General Guidelines for Electronic Equipment 

• MIL-W-5088L, Military Specification, Wiring, Aerospace Vehicle 

• NAVAIR 01-1A-505, Technical Manual, Installation Practices, Aircraft Electric 

and Electronic Wiring 

• Air Force T.O. 1-1A-14, Technical Manual, Installation Practices, Aircraft 

Electric and Electronic Wiring 

• NAVWAG Guideline D5-GI-1188 

c. Aircraft Manufacturer Specifications 

• Airbus Industrie Manual 20-33-10, Electrical Standard Practices 

• Boeing Standard D6-54446, 20-00-14, Wiring Practices Manual 

• Boeing Specification Support Standard BSS 7324F, Procedure for Testing 

Electrical Wire and Cable 

d. Miscellaneous Documentation

• Raytheon—Indianapolis and FAA report Aircraft Wire System, 

Recommendations for a TSO to Address Minimum Safety Performance of 30 

June 2003 

• Naval Avionics Center Report TR-2333, Testing of Selected Aircraft Electrical 

Wire Insulations 

• McDonnell Douglas Corporation report MDC J1530: 09/73, Engineering Report, 

Vibration of DC-10 Wire Bundles 

• McDonnell Douglas Corporation report MDC J1530/01: 08/74, Engineering 

Report, Vibration of DC-10 Wire Bundles 

• McDonnell Douglas Corporation report MDC J6573: 04/76, Interim Engineering 

Methods Authorization Report 

• McDonnell Douglas Corporation report MDC J6998: 09/76, Final Engineering 

Methods Authorization Report, Aircraft Wire Containment 

45
• ASTRAC HWG ESWPM 10/31/02 

• McDonnell Aircraft Company Report MDC B0482, Performance Comparison of 

M81381/9, M22759/19, M22759/33, and Non-MIL Spec Wire and Cable 

• ASTRAC Task 6: Wire Systems Certification Requirements Harmonization 

Working Group Final Report 

• ASTRAC Transport Aircraft Intrusive Inspection Project, An Analysis of the 

Wire Installations of Six Decommissioned Aircraft 

8. REFERENCES. 

1. ATSRAC Transport Aircraft Intrusive Inspection Project (An Analysis of the Wire 

Installations of Six Decommissioned Aircraft), section, Research Recommendations of 

the Intrusive Inspection Working Group, 29 December 2000. 

2. NAC Report TR-2333, “Testing of Selected Aircraft Electrical Wire Insulations,” 8 June 

1983. 

3. ATSRAC Task 6 Report, “Wire Systems Certification Requirements Harmonization 

Working Group,” 29 October 2002. 

4. Douglas Aircraft Company, Engineering Report MDC-J1530/01, “Vibration of DC-10 

Wire Bundles,” 19 August 1974. 

5. SAE AS4373, “Test Methods for Insulated Electric Wire, Method 703, Dynamic CutThrough.” 

46
APPENDIX A—REGULATIONS, STANDARD PRCTICES, AND 

PREVIOUS TEST DOCUMENTATION 

Note: Titles of documents and page numbers are in boldface type. Information from documents 

is in regular type without quotations. Raytheon remarks and summaries of specific information 

are noted as a “comment.” 

I. REGULATIONS, PROPOSED REGULATIONS, AND DESIGN SPECIFICATIONS

1. ADVISORY CIRCULAR AC 43.13-1B: ACCEPTABLE METHODS, TECHNIQUES, 

AND PRACTICES. AIRCRAFT INSPECTION AND REPAIR SEPTEMBER 8, 1998, 

DEPARTMENT OF TRANSPORTATION, FEDERAL AVIATION ADMINISTRATION

Page 11-24 

a. Mechanical Strength of Wires. If it is desirable to use wire sizes smaller than #20, particular 

attention should be given to the mechanical strength and installation handling of these wires, e.g., 

vibration, flexing, and termination. Wire containing less than 19 strands must not be used. 

Consideration should be given to the use of high-strength alloy conductors in small gauge wires 

to increase mechanical strength. As a general practice, wires smaller than size #20 should be 

provided with additional clamps and be grouped with at least three other wires. They should also 

have additional support at terminations, such as connector grommets, strain relief clamps, 

shrinkable sleeving, or telescoping bushings. They should not be used in applications where they 

will be subjected to excessive vibration, repeated bending, or frequent disconnection from screw 

termination. 

Page 11-35 

Installation Precautions for Small Wires. As a general practice, wires smaller than size #20 must 

be provided with additional clamps, grouped with at least three other wires, and have additional 

support at terminations, such as connector grommets, strain-relief clamps, shrinkable sleeving, or 

telescoping bushings. They should not be used in applications where they will be subjected to 

excessive vibration, repeated bending, or frequent disconnection from screw terminations. 

Page 11-36 

11-78. SUBSTITUTIONS. In the repair and modification of existing aircraft, when a 

replacement wire is required, the maintenance manual for that aircraft must first be reviewed to 

determine if the original aircraft manufacturer (OAM) has approved any substitution. If not, then 

the OAM must be contacted for an acceptable replacement. 

a. MIL-W-5088L Wiring, Aerospace Vehicle, Appendix A lists wire types that have been 

approved for military aerospace applications in open and protected wiring applications. These 

wires could potentially be used for substitution when approved by the OAM. 

A-1
Pages 11-45 through 11-46 

11-97. WIRING REPLACEMENTS. Wiring must be replaced with equivalent wire (see 

paragraph 11-78) when found to have any of the following defects: 

a. Wiring that has been subjected to chafing or fraying, that has been severely damaged, or that 

primary insulation is suspected of being penetrated. 

b. Wiring on which the outer insulation is brittle to the point that slight flexing causes it to 

crack. 

c. Wiring having weather-cracked outer insulation. 

d. Wiring that is known to have been exposed to electrolyte or on which the insulation appears 

to be, or is suspected of being, in an initial stage of deterioration due to the effects of electrolyte. 

e. Check wiring that shows evidence of overheating (even if only to a minor degree) for the 

cause of the overheating. 

f. Wiring on which the insulation has become saturated with engine oil, hydraulic fluid, or 

another lubricant. 

g. Wiring that bears evidence of having been crushed or severely kinked. 

h. Shielded wiring on which the metallic shield is frayed and/or corroded. Cleaning agents or 

preservatives should not be used to minimize the effects of corrosion or deterioration of wire 

shields. 

i. Wiring showing evidence of breaks, cracks, dirt, or moisture in the plastic sleeves placed over 

wire splices or terminal lugs. 

j. Sections of wire in which splices occur at less than 10-foot intervals, unless specifically 

authorized, due to parallel connections, locations, or inaccessibility. 

k. When replacing wiring or coaxial cables, identify them properly at both equipment power 

source ends. 

l. Testing of the electrical and chemical integrity of the insulation of sample wires taken from 

areas of the aircraft that have experienced wiring problems in the past, can be used to supplement 

visual examination of the wire. The test for chemical integrity should be specific for the 

degradation mode of the insulation. If the samples fail either the electrical or chemical integrity 

tests, then the wiring in the area surrounding the sampling area is a candidate for replacement. 

2. ADVANCEMENT HANDBOOK FOR AVIATION ELECTRICIANS MATE (AE), 

10/15/2001 

Comment: There is no information pertaining to mixing of dissimilar wire types in bundles. 

A-2 
3. DEPARTMENT OF TRANSPORTATION, FEDERAL AVIATION 

ADMINISTRATION, POLICY STATEMENT NUMBER ANM-01-04; SYSTEM WIRING 

POLICY FOR CERTIFICATION OF PART 25 AIRPLANES: 01/28/02 

Bullet in paragraph 4 of section titled “Disposition of Comments” 

Comment: Issues relating to the mixing of wire types are not addressed. Mixing of wire types is 

not addressed in this policy statement. Wires in a bundle must be securely clamped and bound 

and be compatible with their environment (i.e., vibration, temperature, etc.). These details are 

addressed in the design and installation requirements of the wire. These requirements are called 

out in the installation drawings. 

4. ITSS (MATMEP) F/A-18 DUTY AREA, AIRCRAFT ELECTRICAL TECHNICIAN 

(MOS 6337): 08/2002 

Comment: There is no information pertaining to mixing of dissimilar wire types in bundles. 

5. MIL-E-5400T, ELECTRONIC EQUIPMENT, AEROSPACE, GENERAL 

SPECIFICATION FOR: 11/16/79 

Comment: There is no information pertaining to mixing of dissimilar wire types in bundles. 

6. MIL-HDBK-5400, ELECTRONIC EQUIPMENT, AIRBORNE, GENERAL 

GUIDELINES FOR: 11/30/95 

Comment: There is no information pertaining to mixing of dissimilar wire types in bundles. 

7. MIL-HDBK-454, GENERAL GUIDELINES FOR ELECTRONIC EQUIPMENT, 

(GUIDELINE 71): 11/03/2000 

Comment: There is no information pertaining to mixing of dissimilar wire types in bundles. 

8. MIL-W-5088L, WIRING, AEROSPACE VEHICLE: 05/10/91 

(Same as SAE AS50881A: 04/01/2000) 

3.3.4 Commonality. An objective in the selection of parts shall be to maximize commonality 

and minimize the variety of wiring components and related servicing tools required in the 

construction, installation, and maintenance of the electrical wiring system. 

9. SAE ARP4404 REV A, AIRCRAFT ELECTRICAL INSTALLATIONS: 07/01/2002 

PAGES 52-53 

9.1 General 

The selection of proper type and size of wire for any aircraft circuit is as important as selecting 

the proper protector for the wire. Improper wire selection, either as to type, size, or poor wire 

routing can make an otherwise good electrical system unsafe. 

A-3 
AS50881 covers aspects of wire selection for military aerospace vehicles and is normally used as 

a guide for many commercial programs. This document is maintained on a current basis through 

coordinated industry and military activities and should be used as a reference. Detail data is 

included for current ratings, altitude derating, corona considerations, and list of approved wire 

types. 

9.2 Wire Type Selection 

SAE AS4372 and SAE AS4373 are recommended for the evaluation and proposed selection of 

wire constructions not listed in AS50881 

In the repair and modification of existing aircraft, when replacement wire is required, the 

maintenance manual for that aircraft should first be reviewed to determine if the original aircraft 

manufacturer (OAM) has approved any substitution. If not, then OAM must be contacted for an 

acceptable replacement. 

10. ATSRAC STATEMENT OF CONCERN REGARDING WIRE SEPARATION 

DESIGN CRITERIA, KENT V. HOLLINGER 

08/21/2002

Comment: There is no information pertaining to mixing of dissimilar wire types in bundles. 

11. ATSRAC TASK 6: WIRE SYSTEMS, CERTIFICATION REQUIREMENTS, 

HARMONIZATION WORKING GROUP: FINAL REPORT TO ASTRAC: 10/29/2002 

Page B-7 (iv) 

Wire installed in the same bundle shall be able to withstand the wire-to-wire abrasion. The 

Routing of wires with dissimilar insulation, within the same bundle, is not generally 

recommended, particularly when relative motion and abrasion between wires having dissimilar 

insulation could occur. 

12. AIRCRAFT CIRCULAR, DEVELOPMENT OF ELECTRICAL STANDARD 

WIRING DOCUMENTATION: 10/28/02 

Appendix A and Appendix B. 

Comment: Tables in each Appendix include the following Major Topic: 

WIRE AND CABLE TYPES 

The principle material component of airplane wiring; includes type identification and basic 

description; alternative wire types (replacements, substitutions). 

13. FINAL REPORT, ATSRAC HWG TASK 7, ELECTRICAL STANDARD WIRE 

PRACTICES MANUAL (ESWPM): 10/31/02

Appendix IV 

A-4 
Comment: Table in this Appendix includes the following Major Topic: 

WIRE AND CABLE TYPES 

The principle material component of airplane wiring; includes type identification and basic 

description; alternative wire types (replacements, substitutions). 

14. DEPARTMENT OF TRANSPORTATION, FEDERAL AVIATION ADMINISTRATION 

14 CFR PART 25: 

25.1353 Electrical equipment and installations. 

(a) Electrical equipment, controls and wiring must be installed so that operation of any one 

unit or system of units will not adversely affect the simultaneous operation of any other 

electrical unit or system essential to the safe operation

(b) Cables must be grouped, routed, and spaced so that damage to essential circuits will be 

minimized if there are faults in heavy current-carrying cables 

15. BOEING SPECIFICATION SUPPORT STANDARD BSS 7324F OF 02-DEC-1998, 

PARA 7.57 WIRE-TO-WIRE ABRASION 

Comment: Some aircraft wire types are required to withstand a minimum number of wire-towire rubbing cycles without insulation failure. The number of cycles to failure vary with wire 

type and compression weight. Cycles to failure range from 6,150,000 to 18,500,000 cycles, and 

compression weight varies from 1 to 5 pounds depending on the wire type and insulation 

thickness. Wire-to-wire abrasion between two different types of wires is not required. 

16. MCDONNELL AIRCRAFT COMPANY REPORT MDC B0482 OF 16 DECEMBER 

1987 PARA 3.5.12 

Comment: An abrasion comparison between various wire types was performed. The abrasion 

test consisted of a rubbing action using a small diameter rod compressed on the insulation with 

three different weight values. There was no wire-to-wire abrasion between two different types of 

wires. 

II. AIRCRAFT WIRING PRACTICES DOCUMENTS

1. NAVAIR 01-1A-505.2, TECHNICAL MANUAL: INSTALLATION PRACTICES FOR 

AIRCRAFT ELECTRIC AND ELECTRONIC WIRING: 09/01/1996 

Work Package 004, Wire Selection, Page 3 

6. COMMONALITY. An objective in the selection of parts shall be to maximize commonality 

and minimize the variety of wiring components and related servicing tools required in the 

construction, installation, and maintenance of the electrical wiring system. 

A-5 
Work Package 006, Single Conductor Wire Repair, Page 3 

WARNING: If M81381 type wire is damaged along its length, the damaged area must be 

removed and replaced with appropriate M22759, refer to table 1. 

Work Package 006, Single Conductor Wire Repair, Page 5 

Comment: Table 1 (not repeated here) provides specific MIL-W-81381 to MIL-W-22759 

Replacement wires. 

2. T.O. 1-1A-14 TECHNICAL MANUAL: INSTALLATION PRACTICES FOR 

AIRCRAFT ELECTRIC AND ELECTRONIC WIRING, PAGE 14-3 

14-7. Wire Separation. 

Military Specification MIL-W-5088 restricts the grouping or bundling of certain wires, such as 

electrically unprotected power wiring, and wiring to duplicate vital equipment. Do not add such 

wires to existing bundles unless specifically authorized. 

3. BOEING STANDARD WIRING PRACTICES MANUAL (DOCUMENT D6-54446, 20-

00-14) PAGES 1-9 [Proprietary] 

Comment: Tables 1-7 (not repeated here because of proprietary reasons) provide standard wire 

type replacements permitted for wires. No specific information pertaining to mixing of 

dissimilar wire types was discovered. The Boeing document contained a plethora of substitution 

tables, which allow the substitution of various wire types and show interchangeability for 

general-purpose BMS 13-48 and BMS 13-60 wire types. The tables also showed other generalpurpose wire types that can be replaced by BMS 13-48 and BMS 13-60 wire types. As with 

military wiring practice documents, the promotion of wire mixing in bundles is evident through 

repair and maintenance guidelines and actions. 

4. AIRBUS INDUSTRIE, ELECTRICAL STANDARD PRACTICES MANUAL 

(20-33-10): 10/01/02 

Comment: There is no information pertaining to mixing of dissimilar wire types in bundles.

III. TEST DOCUMENTATION (FORMAL AND INFORMAL)

1. ENG. REPORT, VIBRATION OF DC-10 WIRE BUNDLES, MDC J1530: 09/73 

ENG. REPORT, VIBRATION OF DC-10 WIRE BUNDLES, MDC J1530/01: 08/74 

EMA REPORT, WIRE CONTAINMENT, MDC J6573: 04/76 

FINAL EMA REPORT, AIRCRAFT WIRE, MDC J6998: 09/76 

Comment: The MDC test reports were written in response to wire bundle containment problems 

observed on DC-10 aircraft due to high vibration environments. Reports discuss wire damage by 

containment devices as well as drifting of plastic straps and tying tape. Most (if not all) wire 

A-6 
bundles designed for the test programs use a single wire type. Mixing of wire types into a single 

bundle is not addressed. 

2. INTERVIEW WITH PRINCIPLE TECHNOLOGIST MR. GEORGE SELENSKI AT 

AIR FORCE RELIABILITY LABORATORY WPAFB, OHIO. 

Comment: The U.S. Air Force has allowed composite and aromatic polyimide insulated wire to 

be used together in particular instances, and they do not have specific data at this time to indicate 

that this combination is detrimental to the performance of those applications. Decisions to make 

wire substitutions, which may result in combinations of wire types, are made by the system 

program director on a case-by-case basis. 

3. NAVAL VEHICLE AIRCRAFT WIRING ACTION GROUP (NAVWAG) WIRE 

SUBSTITUTION CHART 

Comment: The Naval Vehicle Aircraft Wiring Action Group (NAVWAG) published a wire 

substitution chart for all wire being used in the fleets in order to permit standardization of wire 

types in cable repair shops. This action has permitted mixed wires to be used in U.S. Navy 

aircraft. No field failures have been reported. 

4. NAVAL AVIONIC CENTER (NAC) AND RAYTHEON RECOMMENDATIONS TO 

NAVAIR FOR WIRE SUBSTITUTION OF CANCELED WIRE SPECIFICATIONS 

Comment: In December 2000 Raytheon recommended MIL-W-22759/32 wire be used as a 

replacement for the cancelled MIL-W-81044/18 wire. Prior to this time similar NAC 

recommendations were made for cancelled MIL-W-5086 wire and wires with known application 

problems such as MIL-W-81381 wire. 

5. INTERVIEWS WITH LOCKHEED MARIETTA SENIOR WIRE ENGINEER 

Comment: Lockheed Marietta has conducted numerous vibration tests (sometime with 

temperature) for various aircraft (C-130, C-141, C-5, F-22, P3 and L-1011) as new wires were 

developed in order to substantiate the use of the new wires in combination with the original wire 

types. No formal reports were written. Over 2 million rubs were performed to get one failure. 

Lockheed Marietta concluded that mixed wires was not an issue. 

6. FIELD DATA ANALYSIS FROM RAYTHEON REPORT “AIRCRAFT WIRE 

SYSTEM RECOMMENDATIONS FOR A TSO TO ADDRESS MINIMUM SAFETY 

PERFORMANCE” JUNE 30, 2003 

The field data from the following databases were reviewed for possible mixed wire incidents. 

There were reported cases of abraded wires, but no indication the abrasions may have been 

caused by mixing of various wire types. 

A-7 
TABLE A-1. FIELD DATA SOURCES

Field Data 

Description 1

Time Frame Data 

was Collected Source of Information 2, 3

NTSB Aviation Accident 

Incident Data System 

1983 – July 2002 https://nasdac.faa.gov/pls/nasdac/ 1, 2

NTSB Aviation Safety 

Reporting System 

1988 – July 2002 https://nasdac.faa.gov/pls/nasdac/ 1,2

Service Difficulty 

Reports (SDRs) 

October 2000 – July 2002 http://av-info.faa.gov/ 3

Airworthiness Directives 

(ADs) 

1979 – July 2002 http://av-info.faa.gov/

Navy Safety Info 1/10/97 to 5/2/01 Information obtained from Cmdr. Bowers 

Miscellaneous and 

ATSRAC Info 

October 1978 – August 2000 Information obtained from the intrusive 

inspection final report and other various 

sources 

NALDA Cable and 

Connector Shop 

January 1996 - July 2002 NALDA 3M Data 

NALDA Electrical Shop January 1996 - July 2002 NALDA 3M Data 

Notes: 

1. During the investigation several web sites were under construction and may no longer be directly accessible 

since the time that the data was gathered. 

2. www.ntsb.gov/ntsb/query.asp was used as an alternate source for backup information. 

3. Several incident reports, which were not on the NTSB website contained information deemed useable and were 

included in this database. 

7. NAC PUBLICATION TR-2333 “TESTING OF SELECTED AIRCRAFT WIRES 

INSULATIONS” 8 JUNE 1983 

Page 2 

A particular wire type could be selected for use in a given part of an aircraft depending upon the 

combination of environmental and mechanical stresses encountered in that particular part of the 

airframe. None of the wires tested demonstrated acceptable qualities for optimum use in all 

areas of Navy aircraft. 

Page 4 

It is recommended that until a universal insulation is developed, a wire should be chosen based 

on its application. 

Comment: In vibration, three bundles of two wire types (15 wires of each type) were tested for 

100, 250, and 512 hours at the AV-8B aircraft cruising test level. One bundle contained 

M22759/16 and M22759/34 wire types, one contained M81381/11 and M22759/16 wire types, 

and one bundle contained M22759/32 and M81381/11 wire types. The wires were tested to 

failure to their maximum dielectric voltage withstand capability. 

A-8 
Comment: Statistically, the results indicated, in general, that harder insulation dielectric 

characteristics are reduced significantly more than the softer insulation. In some cases, the 

reduced voltage capability is nearly 50% from the initial values, but it should be recognized even 

at these reduced levels the wire voltage is still 15 time greater than its rated value. The most 

significant result is that, as the vibration time is continued, the withstand voltage begins to level 

off after 250 hours. It is unknown whether the voltage would continue to stay the same after 512 

hours. Visual observations indicate the reduction in voltage capability is probably due to wireto-wire wear. 

8. RAYTHEON INDIANAPOLIS DESIGN AND AIRCRAFT INSPECTION 

EXPERIENCES 

Comment: Based on Raytheon Indianapolis and NAC wiring designs as well as previous 

military aircraft inspections, it is not uncommon to find two different wire types in the same 

bundles or adjacent bundles. The wire types are necessary as indicated in the NAC TR-2333 

report to meet all the extreme environmental zones in the aircraft. The designer has the option of 

using one wire type by protecting it more in the most extreme environmental zones, but this is 

seldom done for labor cost and weight reasons. 

A-9/A-10
APPENDIX B—TEST PROGRAM 

B.1. BACKGROUND. 

Questions have been raised related to the degradation effects of the insulations of different wire 

types in contact with each other. Chemicals, debris, and other environmental contamination are 

also expected to accelerate degradation on certain insulation surfaces, as well as increase the 

coefficient of friction and cause surface wear. Since many of these wires are constructed with 

very stable polymer insulations, such as polytetrafluoroethylene, the actual chemical interaction 

between them is expected to be negligible. There are potential issues related to the mixing of 

wires with different conductor types as well. A stiffer wire and a harder subsurface to the 

insulations may accelerate the physical interaction of the different wire types. Raytheon has 

experience testing wire with all of these possible interactions. Previously generated test data has 

validated the possibility that these factors could affect the wire-to-wire interaction. 

B.2. TEST DESIGN. 

Physically conditioning wire bundles with vibration accelerates the interactions between the 

wires, such as abrasion and chaffing, and evaluates their characteristic behavior in mixed 

bundles. The magnitude depends on environmental factors such as temperature and humidity; 

chemical stresses with the presence of aircraft fluids; and physical stresses such as the presence 

of foreign matter, vibration, and shock. Three primary mechanisms by which the wire is 

damaged in a mixed state include: 

a. Abrasion and Chaffing. Abrasion is a primary action that will degrade the wire when a 

“sawing” motion is involved. Factors that have been speculated as having influence on 

this degradation mechanism include the hardness of one insulation compared to another, 

tape edges which bite into the another wire, and pigment and mineral fillers that will 

abrade another insulation. 

b. Cut Through. Cut through of the insulation, to expose the underlying conductor, is a 

mechanism that affects the wire integrity. This is the mechanism of one wire pushing 

aside or cutting into another wire by pressure or by the rigidity of the surrounding wires 

that forces the wire into a structural member or other sharp object. Cold flow is a 

mechanism closely related to cut through whereby the insulation will flow, leaving the 

wire less protected with insulation. 

c. Chemical Degradation. The presence of chemicals or debris could be the mechanism that 

is degrading the wire insulation, and the abrasion against another wire may continually 

expose fresh wire surfaces to the damaging effects. 

In addition to those listed, combinations of the above stresses may occur. 

B-1
Several specific conditioning stresses may affect the wire samples based on the above 

degradation mechanisms. These stresses include: 

a. Vibration. Vibration is a major issue in that it increases the overall exposure of the wire 

to cycles of wear. This stress will increase the abrading or sawing mechanisms that may 

be occurring between wires. Operation of aircraft engines and equipment subjects all 

electrical wiring interconnect systems (EWIS) components to some level of vibration. 

Damage to the support system (clamps and straps) or improper replacement of supports 

following maintenance actions can prevent vibration levels from being dampened 

properly and permit increased chafing due to undesirable contact between wire types. 

The introduction of chemicals, dirt, and debris can cause further damage to the EWIS 

when vibration is not restricted properly. 

b. Wire Flexure. Flexure of the wires, especially when twisted, such as in twisted 

conductors, may occur during maintenance and operation. The flexing will cause a force 

between the wires in the bundle to abrade or rub against each other. This may contribute 

to the degradation mechanism occurring between mixed or similar wire types. The 

introduction of chemicals, dirt, and debris can cause further damage to the EWIS when 

this flexure occurs. A flexure test will not be used in this test since it accelerates the 

same degradation mechanism as vibration. Flexure on its own may cause differences in 

the failure rates due to potential differences in the blocking that may occur within the 

conductors. Previous test data has shown that blocked conductor strands, which are 

bonded together, dramatically decrease the flex life of the wire. Having an insulated wire 

with a tin-coated conductor, which more easily blocks with exposure to high heat, mixed 

with an insulated nickel-coated conductor could result in premature failure of the wire. 

This is seen as a design flaw and is not specifically related to the interaction of the two 

wires. Therefore, testing for this interaction was not included in this test program. 

c. Wire-to-Wire Cut Through. Crushing two insulated wires together could cause the 

failure of one of the wires preferentially over another. Although this may not be a 

common failure mechanism, it does demonstrate differences in the physical 

characteristics of the materials. 

d. Wire Flexibility. Flexibility of the wires can affect the amount of stress that is imparted 

on specific wires within the bundle. Rigid wires have the potential of creating more force 

against other components or the structure since it cannot bend out of the way as easily. 

Wire with softer type insulations may be more likely to suffer physically when mixed 

with more rigid wires. The presence of mixed conductor types may cause the additional 

stress to occur between the wires if there is additional stress placed on the bundles, and if 

there is to be an alloy conductor wire mixed with annealed copper conductor wire. Since 

the alloy does not have the same elongation properties, a disproportionate amount of 

stress may be put on the alloy wire, increasing the chance of breakage. Furthermore, the 

additional hardness underneath the insulation may cause increased wear on the wire 

surface. 

B-2 
B.3. DESIGN OF TEST PROGRAM. 

The performance baseline used the same type wires in the same configuration and under the 

same stresses. Simulation testing was performed on the wire properties that are affected by the 

mixing of different wire types. The wire types that were focused upon in group I were the 

following: 

• PVC/glass/nylon 

• Wrapped aromatic polyimide (PI) 

• Cross-linked polyalkane-imide (XPI) 

• Extruded cross-linked ethylene tetrafluoroethylene (XLETFE) 

• Mineral-filled and extruded polytetrafluoroethylene (MF-PTFE and PTFE) 

• PTFE/glass outer braid 

• Wrapped aromatic polyimide/wrapped PTFE composite (PI/PTFE) 

• Annealed and alloy conductor 

Group II of the test plan incorporated some specific examples of interaction with common 

aircraft contamination: hydraulic fluid and metal shavings. Due to the limitations of this effort, 

this portion was not extensively tested, but previous data and selected testing was performed to 

generate conclusions and recommendations regarding the need for future testing. 

The wire bundle samples consisted of a variety of mixed wire combinations using the 

aforementioned wire types. The testing concentrated on the properties of the insulation of the 

wires, with the failure criteria being the loss of the integrity of the wire insulation, leading to the 

potential for direct electrical shorts. The wire-to-wire and bundle tests in tables B-1 and B-2, 

respectively, were decided upon for the program, with the concentration being on the wire 

bundles since that condition more closely simulates the actual environment of the aircraft. 

TABLE B-1. WIRE-TO-WIRE TESTS 

Test Purpose 

Crush To determine which wire insulation types are most 

susceptible to damage. One wire placed over another 

perpendicularly. 

TABLE B-2. BUNDLE TESTS 

Test Purpose 

Vibration Periodically perform visual and electrical evaluations to 

monitor failures. 

Vibration with foreign matter Periodically perform visual and electrical evaluations to 

monitor failures. 

Vibration with chemical 

contamination 

Periodically perform visual and electrical evaluations to 

monitor failures. 

B-3 
Vibration testing was performed with the wire bundles clamped onto fixtures that allowed the 

testing of 48 bundles concurrently. A vibration profile similar to the one documented in Naval 

Avionics Center (NAC) report TR-2333, “Testing of Selected Aircraft Electrical Wire 

Insulations,” dated 8 June 1983, was used for this program. Previous testing has shown that 

significant wire abrasion can be achieved within 500 hours using this method. 

Selection of the wire types took into consideration the differences that fillers can have in the 

PTFE construction by taking types that vary in filler content, and in the construction differences 

of extrusions versus tape-wrapped products. The PTFE insulated wire may behave differently 

than the PI/PTFE due to the rigidity of the polyimide underneath the PTFE wrap. Also, to test 

the theory that conductor differences could play a part in the interaction of wire types, two alloy 

constructions were tested. Three-way combinations were not expected to have more degradation 

than a two-wire interaction. 

The specific wire types tested are shown in table B-3. 

TABLE B-3. WIRE TYPES, SPECIFICATION OR COMMERCIAL EQUIVALENT 

Wire Code Wire Type Part Number 

1 PVC/glass/nylon MIL-W-5086/2-22-9 

2 PI BMS13-51T08C01G22-50 

3 XPI, alloy Spec 88A 

4 XLETFE BMS13-48T08C01G22 

5 XLETFE, alloy MIL-W-22759/42-24-9 

6 PTFE, extruded MIL-W-22759/9-22-9 

7 PTFE, extruded mineral-filled MIL-W-22759/8-22-9 

8 PTFE, tape wrap Not included in program 

9 PTFE/glass MIL-W-22759/1-22-9 

10 PI/PTFE BMS13-60T19C01G22 

11 PI/PTFE, alloy BMS13-60T04C1G22 

B.4. TEST PROCEDURES AND DATA COLLECTION. 

4.1 Group I. 

A total of 48 wire combinations were tested in group I, which consisted of bundles that were 

uncontaminated, and were subjected to 500 hours of vibration conditioning. The unshaded boxes 

shown in table B-4 were the combinations selected for group I of the program. 

B-4 
TABLE B-4. GROUP I TEST WIRE COMBINATIONS 

Wire 

Type 1 2 3 4 5 6 7 8 9 10 11 

1 

2 

3 

4 

5 

6 

7 

8 

9 

10 

11 

The shaded areas are duplicate or very implausible wire combinations that were not tested. Nonmineral-filled PTFE insulated wire is not normally approved for use in open wire harnesses; 

however, it was included in this study to baseline the PTFE with the mineral filler. Nylon can 

crack off the insulation, leaving behind glass braided PVC insulated wire. (Other wire types 

incorporate the use of glass braid in the outer layer of larger gauge sizes for mechanical 

protection.) It is anticipated that wire in this condition will be replaced at the same time that the 

new wire is added, eliminating the need to have a glass braid vibration test. Nylon, which cracks 

off the wire, can cause foreign object damage in the wire bundles that may accelerate the 

degradation. Fluids, metal shavings, and other debris may also accelerate the degradation of the 

wire. Coaxial cables generally have FEP, PTFE, or XLETFE insulations that would behave 

similarly to the wires listed in this test program; however, rubber types are not incorporated in 

this test program. Therefore, twisted pairs were tested in a limited fashion, since it is possible 

that these constructions would increase the stress placed on adjacent wire. The ultimate 

degradation mechanism for the two wire types, however, would be identical. 

B.4.1.1 Assembly of Bundles. 

Similar to the NAC TR-2333 testing, wire bundles consisted of 20 wires of the same or two 

different types of insulation. Each bundle consisted of 12 single wires and 4 twisted pairs that 

were cut to approximately 36 inches in length. For bundles containing two wire types, half of 

the singles and twisted pairs were of each wire type. The wires were installed so that each wire 

type would have single wires and twisted pairs located in the outer and inner portions of the 

bundles. Annealed copper type constructions were 22 gauge, whereas alloy type conductors 

were 24 or 22 gauge, indicative of the actual sizes used in the aircraft. One end of each wire was 

terminated with an electrical contact and installed in a connector. The unterminated end of each 

wire was dipped in RTV to prevent dielectric withstand voltage or insulation resistance failures 

from adjacent exposed conductors rather than wear from the vibration testing. Tiedown straps 

and lacing string were alternately used on the bundles to contain the wires, and MS21919 

cushion clamps were used to secure the bundles to the vibration fixtures. The clamps mounted 

on the vibrated center plates were 11 inches apart. The lacing string and the tiedown strap 

B-5 
installed on the bundle between those clamps were approximately 3 inches from the clamps. The 

lacing string and tiedown strap installed between the clamps on the stationary plates and the 

vibrating center plate were spaced at approximately 3-inch intervals. A bend was put into the 

nonterminated end of each bundle, and it was secured with cushion clamps to a stationary plate 

that was perpendicular to the vibrating center plate (see figures D-14 and D-15 in appendix D). 

In the NAC TR-2333 test program, a bend was placed in both ends of the bundle, but for this 

program, only one end contained a bend so that the impact of this configuration could be 

compared to that of a straight bundle. 

B.4.1.2 Environmental Conditioning and Electrical Testing. 

The bundles were subjected to the vibration profile shown in figure B-1. This profile is similar 

to the one that produced the insulation wear documented in NAC TR-2333. The vibration testing 

was stopped after 100, 250, and 500 cumulative hours for visual inspection and dry insulation 

resistance and dielectric withstand voltage testing. The bundles remained on the fixtures for the 

visual examination and dry electrical testing. After this testing had been completed, the bundles 

were removed from vibration fixtures and subjected to wet insulation resistance and dielectric 

withstand voltage testing. The clamps, tiedown straps, and lacing string were then removed to 

permit a more thorough visual inspection of the wires and surfaces of the support components 

that were in contact with the wires. 

FIGURE B-1. RANDOM VIBRATION PROFILE 

B-6 
B.4.1.3 Specific Tests. 

Detailed descriptions of the tests performed during the execution of the group I test program 

follow. 

a. Visual Inspection. After 100, 250, and 500 hours of vibration, the wire bundles were 

inspected while still mounted on the test fixtures. The inspections were designed to 

document things such as damage to the wires and support components; rotation of the 

heads of the tie wraps; twisted pairs separating from the bundles; wear marks on the 

fixtures from wires, straps, and lacing string; and slippage of bundles in the cushion 

clamps. 

b. Dry Electrical Testing. After 100, 250, and 500 hours of vibration conditioning, the 

fixtures and wire bundles were removed from the vibration table and subjected to dry 

electrical tests using a DITMCO test station. The parameters of the testing were as 

follows: 

• Insulation resistance: 

500 Vdc, 1000 megohms pass/fail threshold, 1 second dwell 

• Dielectric withstand voltage: 

1000 Vac (500 Vac/second ramp), 1 mA leakage current, 1 second dwell 

The unterminated end of each wire was dipped in RTV to prevent dielectric withstand 

voltage or insulation resistance failures from adjacent exposed conductors. 

c. Wet Electrical Testing. After being subjected to the 500 hours of vibration conditioning, 

visual examination, and dry electrical testing, the bundles were removed from the test 

fixtures and soaked for a minimum of 1 hour in a 5% sodium chloride water bath, then 

subjected to wet electrical testing using the following parameters: 

• Insulation resistance: 

500 Vdc, 1000 megohms pass/fail threshold, 1 minute dwell time 

• Dielectric withstand voltage: 

1000 Vac (500 Vac/second ramp), 1 mA leakage current, 1 minute dwell time 

d. Visual Inspection of Disassembled Bundles. Following the wet electrical testing, the 

clamps, tiedown straps, and lacing string were removed, and the wires were separated to 

allow for a more thorough inspection of the complete insulation surface. The inspections 

were designed to document outer wire wear from the clamps, plate, straps, and lacing 

string; inner bundle wire-to-wire wear; and wear on the clamps, straps; and lacing string. 

B-7 
B.4.2 Group II. 

Twenty-four of the original forty-eight wire bundle types were selected to be contaminated with 

fluid, and a similar set of twenty-four to be contaminated with metal shavings. The selected 

combinations are shown by the unshaded cells in table B-5. 

TABLE B-5. GROUP II TEST COMBINATIONS 

Wire 

Type 1 2 3 4 7 9 10 11 

1 

2 

3 

4 

7 

9 

10 

11 

B.4.2.1 Assembly of Bundles. 

The bundles were supported and clamped the same as in group I. 

B.4.2.2 Environmental Conditioning. 

The center sections of one set of the 24 wire combinations in table B-5 were soaked for 4 hours 

in Skydrol 500B4 hydraulic fluid, which meets Standard SAE AS1241, “Fire Resistant 

Phosphate Ester Hydraulic Fluid For Aircraft,” at a temperature of approximately 50°C, then 

allowed to drip dry. 

An equivalent set of wire bundles was contaminated with aluminum drill shavings by birdcaging the center section of the bundles before installing the clamps, tiedown straps, and lacing 

string to allow the shavings to become entrapped within the bundle. 

The bundles were subjected to the same vibration profile as in group I. The vibration testing was 

stopped after 100 and 250 cumulative hours for visual inspection and dry insulation resistance 

and dielectric withstand voltage testing. The bundles remained on the fixtures for the visual 

examination and dry electrical testing. After this testing was completed, the bundles were 

removed from the vibration fixtures and subjected to wet insulation resistance and dielectric 

withstand voltage testing. The clamps, tiedown straps, and lacing string were then removed to 

permit a more thorough visual inspection of the wires and surfaces of the support components 

that were in contact with the wires. 

B-8 
B.4.2.3 Specific Tests. 

Prior to the vibration conditioning, the bundles were subjected to dry insulation resistance and 

dielectric withstand voltage testing. No failures were noted. Following the environmental 

conditioning, the same tests were performed as in group I. 

a. Visual Inspection. After 100 and 250 hours of vibration, the wire bundles were inspected 

while still mounted on the test fixtures. The inspections were designed to document 

things such as damage to the wires and support components; rotation of the heads of the 

tie wraps; twisted pairs separating from the bundles; wear marks on the fixtures from 

wires, straps, and lacing string; and slippage of bundles in the cushion clamps. 

b. Dry Electrical Testing. After 100 and 250 hours of vibration conditioning, the fixtures 

and wire bundles were removed from the vibration table and subjected to dry electrical 

tests using a DITMCO test station. The parameters of the testing were as follows: 

• Insulation resistance: 

500 Vdc, 1000 megohms pass/fail threshold, 1-second dwell 

• Dielectric withstand voltage: 

1000 Vac (500 Vac/second ramp), 1 mA leakage current, 1-second dwell 

The unterminated end of each wire was dipped in RTV to prevent dielectric withstand 

voltage or insulation resistance failures from adjacent exposed conductors. 

c. Wet Electrical Testing. After being subjected to the 250 hours of vibration conditioning, 

visual examination, and dry electrical testing, the bundles were removed from the test 

fixtures and soaked for a minimum of 1 hour in a 5% sodium chloride water bath, then 

subjected to wet electrical testing using the following parameters: 

• Insulation resistance: 

500 Vdc, 1000 megohms pass/fail threshold, 1-minute dwell time 

• Dielectric withstand voltage: 

1000 Vac (500 Vac/second ramp), 1 mA leakage current, 1-minute dwell time 

d. Visual Inspection of Disassembled Bundles. Following the wet electrical testing, the 

clamps, tiedown straps, and lacing string were removed, and the wires were separated to 

allow for a more thorough inspection of the complete insulation surface. The inspections 

were designed to document outer wire wear from the clamps, plate, straps, and lacing 

string; inner bundle wire-to-wire wear; and wear on the clamps, straps, and lacing string. 

B-9 
B.4.3 Group III—Crush Test. 

Fourteen-inch lengths of untested wires were subjected to a crush test at room temperature to 

determine which wire insulations were more susceptible to damage. The test method was a 

variation to the standard dynamic cut through test, with the difference being that two 

perpendicular wires are compressed against each other instead of a blade being pressed on a 

wire. The same 24 wire combinations that were evaluated in group II were subjected to the crush 

test. For each combination of wires tested, eight crushes were performed at approximately 1/2-

inch intervals. Half of the crushes were performed with an 80-pound load applied and half with 

a 120-pound load. The wires were then evaluated for damage. 

B-10 
APPENDIX C—TEST DATA 

TABLE C-1. GROUP I VISUAL OBSERVATIONS ON MOUNTED BUNDLES 

On Bundle Number* 

Condition Observed 

After 100 hrs 

Vibration 

After 250 hrs 

Vibration 

After 500 hrs 

Vibration 

Twisted pairs separating 

from bundle 

Strap rubbing on center 

plate 

2-12, 14, 18, 22, 23, 

28, 31, 37-39, 41, 45-

47 

2-12, 14, 16, 18, 20, 

22, 23, 26, 28, 30, 

31, 35, 37-39, 41, 

45-47 

1, 2, 8-10, 14, 18, 

22, 28, 30, 31, 35, 

37-40, 45, 47 

Wire rubbing on plate 1, 2, 4-6, 8, 10, 12, 

14, 16-18, 20, 22, 25, 

27-33, 35-40, 42-47 

1, 2, 4-6, 8, 10, 12-

15, 17-22, 24, 25, 

27-33, 35-47 

1, 2, 4-6, 8, 10-12, 

14, 17-20, 22, 24, 

25, 27-33, 35-37, 39-

48 

White residue from clamp 

or wire insulation 

1, 13, 25, 36, 37, 48 1, 5, 8, 12, 13, 15, 

18, 20, 22, 24, 25, 

27, 29, 32, 36, 37, 

39, 48 

Bundle slipping in clamp 11-13, 23-25, 29, 35, 

36, 47, 48 

1, 2, 4, 5, 11-13, 17, 

20, 23-25, 29, 30, 

33, 35, 36, 47, 48 

All 

Lacing string cutting into 

wire 

5, 18, 22, 30, 41 1, 5, 18, 22, 30, 32, 

36, 41, 44, 48 

Wire stripe wearing off 16, 43, 45, 47 16, 43, 45, 47 

Clamp cutting insulation 1, 2, 12, 14, 25, 27, 

36, 39, 47, 48 

1, 2, 5, 12, 13, 17, 

28, 36, 37, 48 

Strap rubbing on flat side 

plate 

6, 9, 37, 43, 47 

*See table C-5 for wire types found in each bundle number. 

C-1 
TABLE C-2. GROUP I DRY ELECTRICAL FAILURES FOLLOWING 250 HOURS OF 

VIBRATION TESTING* 

Bundle 

No. 

Wire 

Codes 

Failed 

Cavity 

Wire 

Code 

Single or 

Pair IR (Ohms) DWV 

18 6, 5 J2-5 5 P 9.484 km pass Fail 

20 6, 6 J2-15 6 P 1.147 Fail 

 *No failures were noted after 100 hours of vibration.

TABLE C-3. GROUP I DRY ELECTRICAL FAILURES FOLLOWING 500 HOURS OF 

VIBRATION TESTING*

Bundle 

No. 

Wire 

Codes 

Failed 

Cavity 

Wire 

Code 

Single or 

Pair IR (Ohms) DWV 

13 7, 7 J2-10 7 P 6.520 km pass Fail 

15 10, 9 J2-8 10 S 13.82 km pass Fail 

16 3, 2 J2-8 3 S 7.405 km pass Fail 

17 10, 7 J2-8 10 S 5.192 km pass Fail 

19 11, 4 J2-8 11 S 5.739 km pass Fail 

20 6, 6 J2-8 6 S 8.234 km pass Fail 

*Dry electrical results are considered suspect. 

C-2 
TABLE C-4. GROUP I WET ELECTRICAL FAILURES FOLLOWING 500 HOURS OF 

VIBRATION TESTING 

Bundle 

No. 

Wire 

Codes 

Failed 

Cavity 

Wire 

Code 

Single or 

Pair IR (Ohms) 

DWV 

(Pass/Fail)

11 5, 5 J2-19 5 P 11.44 k Fail 

11 5, 5 J2-5 5 P 22.66 km pass Fail 

12 9, 9 J2-11 9 S 5.533 k Fail 

12 9, 9 J2-13 9 S 3.776 k Fail 

12 9, 9 J2-15 9 P 1.987 k Fail 

12 9, 9 J2-3 9 S 5.197 k Fail 

12 9, 9 J2-6 9 S 6.297 k Fail 

12 9, 9 J2-8 9 P 2.042 k Fail 

17 10, 7 J2-9 10 P low Fail 

20 6, 6 J2-10 6 P 4.210 k Fail 

20 6, 6 J2-14 6 P 5.301 k Fail 

20 6, 6 J2-15 6 P 4.946 k Fail 

20 6, 6 J2-17 6 S 6.705 k Fail 

20 6, 6 J2-20 6 P 3.049 k Fail 

20 6, 6 J2-4 6 P 12.18 k Fail 

20 6, 6 J2-5 6 P 4.874 k Fail 

20 6, 6 J2-7 6 S 9.451 k Fail 

20 6, 6 J2-9 6 P 7.489 k Fail 

21 3, 3 J2-7 3 S 11.14 km pass Fail 

24 9, 1 J2-19 9 P 7.167 k Fail 

24 9, 1 J2-9 9 P 3.247 km pass Fail 

25 9, 6 J1-19 6 P 1.611 k Fail 

25 9, 6 J1-20 6 P 2.052 k Fail 

25 9, 6 J1-21 9 S 4.210 k Fail 

25 9, 6 J1-25 9 P 1.025 k Fail 

25 9, 6 J1-27 6 S 5.881 k Fail 

25 9, 6 J1-29 6 P 6.681 k Fail 

25 9, 6 J1-30 6 P 6.483 k Fail 

25 9, 6 J1-32 9 S 5.346 k Fail 

29 7, 5 J1-20 5 P 814.6 km pass Fail 

36 9, 7 J1-24 9 P 1.711 k Fail 

36 9, 7 J1-26 7 S 3.816 k Fail 

36 9, 7 J1-28 7 S 4.379 k Fail 

36 9, 7 J1-34 9 P 533.7 Fail 

*All DWV failures were determined to be due to installation rather than wire-to-wire wear. 

C-3 
C-4

TABLE C-5. GROUP I POSTTEST VISUAL INSPECTION 

Bundle No. 1 2 3 4 5 6 7 8 9 10 11 12 

Wire Types 7/1 11/10 11/9 11/2 11/7 4/4 10/4 7/2 11/3 9/4 5/5 9/9 

Outer Bundle Wear From: 

Plate L/N N/N N/L L/N L/L L/L N/L L/N N/L L/N S/S L/L Clamps M/N M/M N/N M/L M/M N/N M/N L/N M/M L/N N/N S/S Straps L/N N/N N/L L/N L/L L/L L/L L/N L/N L/N N/N L/L String N/N N/N N/N N/L N/N N/N N/N N/N N/N N/N N/N N/N Photos Yes Yes No Yes No No No No No No Yes Yes 

Wire Wear: 

Single/Single N/N N/N N/N N/L N/N N/N N/N N/L N/L N/N L/L N/N Pair/Pair N/N N/N N/N N/L N/N N/N N/N N/L N/L N/N N/N N/N Pair/Single N/N N/N N/N N/N N/N N/N N/N N/L N/L N/N L/L N/N Photos No No No No No No No No No No No No 

Wear on Support: 

Clamps M N L L N N L L L L L M Straps N N L L N N L L L N N L String N N N N N N N N N N N N Photos Yes No No No No No No No No No No Yes 

 L =  M = 
C-5

TABLE C-5. GROUP I POSTTEST VISUAL INSPECTION (Continued)

Bundle No. 13 14 15 16 17 18 19 20 21 22 23 24 

Wire Types 7/7 11/11 10/9 3/2 10/7 6/5 11/4 6/6 3/3 7/6 10/5 9/1 

Outer Bundle Wear From: 

Plate M/M N/N N/L M/N L/N N/M M/N S/S N/N S/N N/N M/L Clamps S/S M/M L/N M/L M/M N/N M/N S/S M/M M/L M/N S/L Straps L/L L/L N/L N/N L/L L/L L/L L/L N/N L/L L/L N/N String N/N N/N N/N N/N N/N N/N N/N N/N N/N N/N N/N N/N Photos Yes Yes No Yes Yes Yes Yes Yes Yes Yes No Yes 

Wire Wear: 

Single/Single N/N N/N N/N M/L N/N N/N N/N N/N M/M N/N N/N N/N Pair/Pair N/N N/N N/N M/L N/N N/N N/N N/N M/M N/N N/N N/N Pair/Single N/N N/N N/N M/L N/N N/N N/N N/N M/M N/N N/N N/N Photos No No No No No No No No Yes No No No 

Wear on Support: 

Clamps L N L L L L L L L L L M Straps N L N N L L N L N L L N String N N N N N N N N N N N N Photos No No No No No No No No Yes No No No 
C-6

TABLE C-5. GROUP I POSTTEST VISUAL INSPECTION (Continued)

Bundle No. 25 26 27 28 29 30 31 32 33 34 35 36 

Wire Types 9/6 5/3 9/5 2/2 7/5 11/6 4/3 5/1 5/2 9/2 10/10 9/7 

Outer Bundle Wear From: 

Plate N/N N/N L/N N/N L/L L/M L/L L/L L/M N/M M/M N/N Clamps S/S N/M L/N L/L M/L N/N N/L L/N N/N N/N M/M S/S Straps L/L L/N N/N N/N L/N N/N L/N N/N N/N L/L N/N N/L String N/N N/N N/N N/N L/N L/N N/N N/N N/N N/N N/N N/N Photos Yes Yes No No Yes Yes No No No No No Yes 

Wire Wear: 

Single/Single N/N N/L N/N L/L N/N N/N N/M N/N L/L N/L N/N N/N Pair/Pair N/N N/M N/N L/L L/N N/N N/M L/N L/L N/L N/N N/N Pair/Single N/N N/M N/N L/L L/N N/N N/M N/N L/L N/L N/N N/N Photos No No No No No No Yes No No No No No 

Wear on Support: 

Clamps M L L L L N L L L L L M Straps N N N N N N N N N N N N String N N N N N N N N N N N N Photos No No No No No No No No No No No No 
C-7

TABLE C-5. GROUP I POSTTEST VISUAL INSPECTION (Continued) 

Bundle No. 37 38 39 40 41 42 43 44 45 46 47 48 

Wire Types 7/4 10/3 4/1 5/4 6/2 6/3 4/2 7/3 10/2 9/3 11/5 1/1 Outer Bundle Wear From: Plate N/N N/N L/N N/L S/N M/M L/N L/M L/L L/L L/N L/L Clamps L/N M/M L/N N/N N/N N/L N/N M/M M/L N/N L/N N/N Straps N/N L/N N/N N/N L/N L/N N/N L/N N/N L/N L/N N/N String N/N N/N N/N N/N N/N N/N N/N N/N N/N N/N N/N N/N Photos No Yes No No Yes No No Yes No No No No Wire Wear: Single/Single N/N N/L N/N N/N N/L N/M N/L L/M L/L N/L N/N N/N Pair/Pair N/N N/L N/N N/N N/L N/M N/L N/M L/L N/L N/N N/N Pair/Single N/N N/L L/N N/N N/L L/M N/L L/M L/L N/L N/N N/N Photos No No No No No Yes No No No No No No Wear on Support: Clamps L L L N N L L L L L N M Straps L N N N N N N L L N N N String N N N N N N N N N N N N Photos No No No No No No No No No No No No 
TABLE C-6. GROUP I SUMMARY OF RESULTS BY WIRE TYPE 

Wire Code 1 Group I 

With 

Code Bundle 

Clamp 

Diameter 

Bundle 

Diameter

Diameter 

Difference

Wear 

From 

Wire 

DWV, 

No. 

Failed 

Slip at 

100 

Hrs? 

Wear From 

Clamps 

Wear 

From 

Plate 

1 48 0.438 0.42 0.018 N Y N L 

2 

3 

4 39 0.375 0.35 0.025 N N N N 

5 32 0.375 0.336 0.039 N N N L 

6 

7 1 0.438 0.414 0.024 N N N N 

9 24 0.5 0.445 0.055 N Y L L 

10 

11 

 

Wire Code 2 Group I 

With 

Code Bundle 

Clamp 

Diameter 

Bundle 

Diameter

Diameter 

Difference

Wear 

From 

Wire 

DWV, 

No. 

Failed 

Slip at 

100 

Hrs? 

Wear From 

Clamps 

Wear 

From 

Plate 

1 

2 28 0.313 0.263 0.05 L N L N 

3 16 0.313 0.26 0.053 L N L N 

4 43 0.313 0.272 0.041 L N N N 

5 33 0.313 0.258 0.055 L N N M 

6 41 0.313 0.3 0.013 L N N N 

7 8 0.375 0.336 0.039 L N N N 

9 34 0.375 0.367 0.008 L N N M 

10 45 0.313 0.258 0.055 L N L L 

11 4 0.313 0.258 0.055 L,N N L N 

Key: N = No 

 Y = Yes 

 N = None 

 L = Low 

 M = Moderate 

 S = Severe 

C-8
TABLE C-6. GROUP I SUMMARY OF RESULTS BY WIRE TYPE (Continued) 

Wire Code 3 Group I 

With 

Code Bundle 

Bundle 

Diameter

Diameter 

Difference

Wear 

From 

Wire 

DWV, 

No. 

Failed

Clamp 

Diameter 

Slip at 

100 

Hrs? 

Wear 

From 

Clamps 

Wear 

From 

Plate 

1 

2 16 M N M M 

3 21 0.313 0.258 0.055 M 1 N M N 

4 31 0.313 0.269 0.044 M N L L 

5 26 0.313 0.255 0.058 M,L N M N 

6 42 0.313 0.297 0.016 M N L M 

7 44 0.375 0.333 0.042 M N M M 

9 46 0.375 0.364 0.011 L N N L 

10 38 0.375 0.375 0 L N M N 

11 9 0.313 0.255 0.058 L N M L 

 

Wire Code 4 Group I 

With 

Code Bundle 

Clamp 

Diameter 

Bundle 

Diameter

Diameter 

Difference

Wear 

From 

Wire 

DWV, 

No. 

Failed

Slip at 

100 

Hrs? 

Wear 

From 

Clamps 

Wear 

From 

Plate 

1 39 L N L L 

2 43 N N N L 

3 31 N N N L 

4 6 0.313 0.28 0.033 N N N L 

5 40 0.313 0.266 0.047 N N N L 

6 

7 37 0.438 0.394 0.044 N N N N 

9 10 0.375 0.375 0 N N N N 

10 7 0.313 0.266 0.047 N N N L 

11 19 0.313 0.266 0.047 N N N N 

Key: N = No 

 Y = Yes 

 N = None 

 L = Low 

 M = Moderate 

 S = Severe 

C-9
TABLE C-6. GROUP I SUMMARY OF RESULTS BY WIRE TYPE (Continued) 

Wire Code 5 Group I 

With 

Code Bundle 

Clamp 

Diameter 

Bundle 

Diameter

Diameter 

Difference

Wear 

From 

Wire 

DWV, 

No. 

Failed

Slip at 

100 

Hrs? 

Wear 

From 

Clamps 

Wear 

From 

Plate 

1 32 L,N N L L 

2 33 L,N N N L 

3 26 N N N N 

4 40 N N N N 

5 11 0.313 0.252 0.061 L,N 2 Y N S 

6 18 0.313 0.294 0.019 N N N M 

7 29 0.375 0.33 0.045 N 1 Y L L 

9 27 0.375 0.361 0.014 N N N N 

10 23 0.313 0.252 0.061 N Y N N 

11 47 0.313 0.252 0.061 N Y N N 

 

Wire Code 6 Group I 

With 

Code Bundle 

Clamp 

Diameter 

Bundle 

Diameter

Diameter 

Difference

Wear 

From 

Wire 

DWV, 

No. 

Failed

Slip at 

100 

Hrs? 

Wear 

From 

Clamps 

Wear 

From 

Plate 

1 

2 41 N N N S 

3 42 L N N M 

4 

5 18 N N N N 

6 20 0.375 0.336 0.039 N 9 N S S 

7 22 0.375 0.375 0 N N L N 

9 25 0.438 0.403 0.035 N 5 Y S N 

10 

11 30 0.313 0.294 0.019 N N N M 

Key: N = No 

 Y = Yes 

 N = None 

 L = Low 

 M = Moderate 

 S = Severe 

C-10
TABLE C-6. GROUP I SUMMARY OF RESULTS BY WIRE TYPE (Continued) 

Wire Code 7 Group I 

With Code Bundle 

Clamp 

Diameter 

Bundle 

Diameter

Diameter 

Difference

Wear 

From 

Wire 

DWV, 

No. 

Failed

Slip at 

100 

Hrs? 

Wear 

From 

Clamps 

Wear 

From 

Plate 

1 1 N N M L 

2 8 N N L L 

3 44 L,N N M L 

4 37 N N L N 

5 29 L,N Y M L 

6 22 N N M S 

7 13 0.438 0.409 0.029 N Y S M 

9 36 0.5 0.44 0.06 N 2 Y S N 

10 17 0.375 0.331 0.044 N N M N 

11 5 0.375 0.331 0.044 N N M L 

 

Wire Code 9 Group I 

With Code Bundle 

Clamp 

Diameter 

Bundle 

Diameter

Diameter 

Difference

Wear 

From 

Wire 

DWV, 

No. 

Failed

Slip at 

100 

Hrs? 

Wear 

From 

Clamps 

Wear 

From 

Plate 

1 24 N 2 Y S M 

2 34 N N N N 

3 46 N N N L 

4 10 N N L L 

5 27 N N L L 

6 25 N 3 Y S N 

7 36 N 2 Y S N 

9 12 0.5 0.47 0.03 N 6 Y S L 

10 15 0.375 0.361 0.014 N N N L 

11 3 0.375 0.361 0.014 N N N L 

Key: N = No 

 Y = Yes 

 N = None 

 L = Low 

 M = Moderate 

 S = Severe 

C-11
TABLE C-6. GROUP I SUMMARY OF RESULTS BY WIRE TYPE (Continued) 

Wire Code 10 Group I 

With 

Code Bundle 

Clamp 

Diameter 

Bundle 

Diameter

Diameter 

Difference

Wear 

From 

Wire 

DWV, 

No. 

Failed

Slip at 

100 

Hrs? 

Wear 

From 

Clamps 

Wear 

From 

Plate 

1 

2 45 L N M L 

3 38 N N M N 

4 7 N N M N 

5 23 N Y M N 

6 

7 17 N 1 N M L 

9 15 N N L N 

10 35 0.313 0.252 0.061 N Y M M 

11 2 0.313 0.252 0.061 N N M N 

 

Wire Code 11 Group I 

With 

Code Bundle 

Clamp 

Diameter 

Bundle 

Diameter

Diameter 

Difference

Wear 

From 

Wire 

DWV, 

No. 

Failed

Slip at 

100 

Hrs? 

Wear 

From 

Clamps 

Wear 

From 

Plate 

1 

2 4 N N M L 

3 9 N N M N 

4 19 N N M M 

5 47 N Y L L 

6 30 N N N L 

7 5 N N M L 

9 3 N N N N 

10 2 N N M N 

11 14 0.313 0.252 0.061 N N M N 

Key: N = No 

 Y = Yes 

 N = None 

 L = Low 

 M = Moderate 

 S = Severe 

C-12
TABLE C-7. GROUP II VISUAL OBSERVATIONS ON MOUNTED BUNDLES 

On Bundle Number* 

Condition Observed After 100 hrs After 250 hrs 

Twisted pairs separating from 

bundle 

All All 

Strap rubbing on plate 50, 54, 56-58, 62-64, 68-71, 75-

79, 81, 83, 85, 90, 91, 96 

Wire rubbing on plate 49, 50, 54-56, 59-66, 68-70, 72, 

75-85, 88-90, 96 

49, 50, 54-56, 59-64, 66, 69, 

73, 77, 80, 81, 83-86, 92, 96 

White, gray, or green residue 

from clamp or wire insulation 

49-54, 60, 61, 63-67, 72, 73, 84, 

85, 87, 96 

49, 51-55, 59, 60, 63, 66, 70, 

72, 73, 77, 84, 85, 87, 92, 94 

Bundle slipping in clamp 49, 50, 53, 55-57, 59-62, 64-69, 

71, 72, 74, 76-86, 88, 91, 95 

49-53, 55, 57, 59, 60-69, 71-

74, 76-84, 86, 88, 91, 92 

Lacing string cutting into wire 56 52, 56, 60 

Torn cushion clamp 59, 72 59, 72, 

Black splatter 58, 61, 62, 66, 67 49, 58, 61, 62, 66, 67, 84 

*See tables C-10 and C-11 for wire types found in each bundle number. 

TABLE C-8. GROUP II DRY ELECTRICAL FAILURES FOLLOWING 

250 HOURS OF VIBRATION TESTING* 

Bundle 

No. 

Wire 

Codes 

Failed 

Cavity 

Wire 

Code 

Single or 

Pair 

IR 

(Ohms) 

DWV 

(Pass/Fail) 

60 9, 9 J1-14 9 p 678.8 m Pass 

60 9, 9 J1-15 9 p 590.4 m Pass 

60 9, 9 J1-17 9 s 819.1 m Pass 

60 9, 9 J1-18 9 s 728.3 m Pass 

60 9, 9 J1-9 9 p 6.321 m Pass 

No failures were noted after 100 hours of vibration. 

*Dry electrical results are considered suspect. 

C-13
TABLE C-9. GROUP II WET ELECTRICAL FAILURES FOLLOWING 

250 HOURS OF VIBRATION TESTING 

Bundle 

No. 

Wire 

Codes 

Failed 

Cavity 

Wire 

Code 

Single or 

Pair 

IR 

(Ohms) 

DWV 

(Pass/Fail) 

49 7, 1 J1-12 1 S 976.4 m Pass 

49 7, 1 J1-14 1 P 379.5 m Pass 

49 7, 1 J1-15 1 P 189.3 m Pass 

50 10, 3 J1-18 10 S 8.6 k Fail 

50 10, 3 J1-19 10 P 6.917 k Fail 

50 10, 3 J1-20 10 P 7.289 k Fail 

60 9, 9 J1-15 9 P 738.2 m Pass 

60 9, 9 J1-9 9 P 830.6 m Pass 

63 4, 1 J1-12 1 S 398.5 m Pass 

63 4, 1 J1-14 1 P 354.4 m Pass 

63 4, 1 J1-15 1 P 428.3 m Pass 

63 4, 1 J1-5 1 P 735 m Pass 

72 1, 1 J1-17 1 S 519.7 m Pass 

72 1, 1 J1-18 1 S 998.3 m Pass 

84 9, 9 J2-12 9 S 6.372 k Fail 

84 9, 9 J2-19 9 P 5.381 k Fail 

84 9, 9 J2-5 9 P 44.48 m Pass 

95 11, 10 J2-13 10 S 814.2 km pass Fail 

For this program analysis, highlighted items are not considered failures since passed DWV. 

C-14
TABLE C-10. GROUP IIF POSTTESTING VISUAL INSPECTION 

Bundle No. 49 50 51 52 53 54 55 56 57 58 59 60 

Wire Types 7/1 10/3 10/9 2/2 10/7 4/2 11/4 7/2 10/2 7/4 11/11 9/9 Outer Bundle Wear From: Plate N/L L/N L/M L/L L/L N/N L/L L/N N/N N/N M/M L/L Clamps N/N S/M N/N M/M N/L L/M L/N L/L L/M N/N L/L L/L Straps L/N M/M L/L M/M M/L N/L L/N L/L L/M L/N L/L L/L String N/N N/N N/N L/L N/N N/N N/N N/M N/N N/N N/N N/N Photos No Yes Yes Yes Yes Yes No Yes No No Yes No Wire Wear: Single/Single N/N L/L N/N M/M N/L N/L N/N L/M N/L N/N N/N M/M Pair/Pair L/N L/L N/N M/M N/N N/N N/N L/M N/L N/N N/N M/M Pair/Single N/N L/L N/N M/M N/N N/N L/N L/M N/L N/N N/N M/M Photos No No No Yes No No No Yes No No No Yes Wear on Support: Clamps M L L L L L N L N L S M Straps N L N N N N N L N L N N String N N N N N N N N N N N N Photos Yes No No No No No No No No No Yes No 

C-15 
TABLE C-10. GROUP IIF POSTTESTING VISUAL INSPECTION (Continued) 

Bundle No. 61 62 63 64 65 66 67 68 69 70 71 72 

Wire Types 7/7 10/10 4/1 3/2 4/4 4/3 10/4 7/3 3/3 9/4 11/10 1/1 Outer Bundle Wear From: Plate M/M S/S M/L M/N N/N L/L N/N N/N L/L L/N N/L N/N Clamps L/L N/N N/N N/N N/N N/M L/N N/L N/N N/N N/N N/N Straps L/L L/L N/N L/L N/N N/N L/N L/L N/N N/N N/N N/N String N/N N/N N/N N/N N/N N/N N/N N/N N/N N/N N/N N/N Photos No Yes No Yes No No No No No No No No Wire Wear: Single/Single N/N N/N N/N L/L N/N N/M N/N N/L L/L N/N N/N N/N Pair/Pair N/N N/N N/N M/M N/N N/M N/N N/L L/L L/N L/L N/N Pair/Single N/N N/N N/N L/L N/N N/M N/N N/L L/L L/N L/L N/N Photos No No No No No No No No No No No No Wear on Support: Clamps L N M L L L L N N L N M Straps N L L L N N N L N N N N String N N N N N N N N N N N N Photos No No No No No No No No No No No No 

C-16
TABLE C-11. GROUP IIM POSTTESTING VISUAL INSPECTION 

Bundle No. 73 74 75 76 77 78 79 80 81 82 83 84 

Wire Types 7/1 10/3 10/9 2/2 10/7 4/2 11/4 7/2 10/2 7/4 11/11 9/9 Outer Bundle Wear From: Plate L/N L/N N/L N/N L/N N/N N/N N/N M/N N/N M/M L/L Clamps L/N L/L N/N L/L N/N N/L N/N N/N N/N N/N N/N S/S Straps L/N L/N L/N N/N L/L N/N L/N L/N L/N L/N L/L L/L String L/N N/N N/N N/N N/N N/N N/N L/N N/N N/N N/N N/N Metal Shavings 

N/N N/N N/N N/N N/N N/N N/N N/N N/N N/N N/N N/N 

Photos No No No No No No No No Yes No Yes Yes Wire Wear: Single/Single N/N N/L N/N L/L N/N N/L N/N N/L N/L N/N N/N N/N Pair/Pair N/N N/L N/N L/L N/N N/L N/N N/L N/L N/N N/N N/N Pair/Single N/N N/L N/N L/L N/N N/L N/N N/L N/L N/N N/N N/N From Shavings 

L/L N/N N/L L/L L/L N/N L/L N/L N/L L/L N/N L/L 

Photos No No No No No No No No No Yes No No Wear on Support: Clamps M L L L L L L S L L N M Straps L N N N L N L N N N L N String N N N N N N N N N N N N From Shavings 

N N N N N N N N N N N N 

Photos No No No No No No No Yes No No No No 

C-17
TABLE C-11. GROUP IIM POSTTESTING VISUAL INSPECTION (Continued) 

Bundle No. 85 86 87 88 89 90 91 92 93 94 95 96 

Wire Types 7/7 10/10 4/1 3/2 4/4 4/3 10/4 7/3 3/3 9/4 11/10 1/1 Outer Bundle Wear From: Plate L/L N/N N/N N/N N/N N/N N/N M/M M/M L/N N/L N/N Clamps M/M M/M N/N L/L N/N N/L L/N L/L L/L N/N N/N N/N Straps L/L N/N N/N N/N N/N N/N L/N N/N N/N N/N N/N N/N String N/N N/N N/N N/N N/N N/N N/N N/N N/N N/N N/N N/N Metal Shavings 

N/N N/N N/L N/N L/L L/L N/N N/N N/N L/N N/N N/N 

Photos Yes Yes No No Yes No No Yes Yes No No No Wire Wear: Single/Single N/N N/N N/N L/N N/N N/L N/N N/L M/M N/N N/N N/N Pair/Pair N/N N/N N/N L/N N/N N/L N/N N/L M/M N/N N/N N/N Pair/Single N/N N/N N/N L/N N/N N/L N/N N/L M/M N/N N/N N/N From Shavings 

L/L L/L L/L L/L N/N L/L N/L L/L N/N L/L L/L L/L 

Photos No No No No No No No Yes Yes No No No Wear on Support: Clamps L L L L L L L L L L N N Straps L N N N N L N N N N N N String N N N N N N N N N N N N From Shavings 

N N N N N N N N N L N N 

Photos No No No No No No No No No No No No 

C-18
TABLE C-12. GROUP II SUMMARY OF RESULTS BY WIRE TYPE 

 Wire Code 1 Group IIF Fluid Group IIM Metal 

With 

Code 

Clamp 

Diameter 

Bundle 

Diameter 

Diameter 

Difference Bundle 

Wear From 

Wire 

DWV, 

No. 

Failed 

Slip at 

100 

Hrs? 

Wear From 

Clamps

Wear From 

Plate Bundle 

Wear From 

Wire 

DWV, 

No. 

Failed 

Slip at 

100 

Hrs? 

Wear From 

Clamps

Wear From 

Plate 

1 0.438 0.42 0.018 72 N Y N N 96 N,L N N N 234 0.375 0.35 0.025 63 N N N L 87 N,L N N N 5 0.375 0.336 0.039 67 0.438 0.414 0.024 49 N Y N L 73 N,L N N N 9 0.5 0.445 0.055 

1011

Wire Code 2 Group IIF Fluid Group IIM Metal 

With 

Code 

Clamp 

Diameter 

Bundle 

Diameter 

Diameter 

Difference Bundle 

Wear From 

Wire 

DWV, 

No. 

Failed 

Slip at 

100 

Hrs? 

Wear From 

Clamps

Wear From 

Plate Bundle 

Wear From 

Wire 

DWV, 

No. 

Failed 

Slip at 

100 

Hrs? 

Wear From 

Clamps

Wear From 

Plate 

C19

12 0.313 0.263 0.05 52 M N M L 76 L Y L N 3 0.313 0.26 0.053 64 L,M Y N N 88 N,L Y L N 4 0.313 0.272 0.041 54 N,L N M N 78 L,N Y L N 5 0.313 0.258 0.055 6 0.313 0.3 0.013 7 0.375 0.336 0.039 56 M Y L N 80 L Y N N 9 0.375 0.367 0.008 

10 0.313 0.258 0.055 57 L Y M N 81 L Y N N 11 0.313 0.258 0.055 

Key: 

N = No N = None M = Moderate Y = Yes L = Low S = Severe 
TABLE C-12. GROUP II SUMMARY OF RESULTS BY WIRE TYPE (Continued) 

Wire Code 3 Group IIF Fluid Group IIM Metal 

With 

Code 

Clamp 

Diameter 

Bundle 

Diameter 

Diameter 

Difference Bundle 

Wear From 

Wire 

DWV, 

No. 

Failed 

Slip at 

100 

Hrs? 

Wear From 

Clamps

Wear From 

Plate Bundle 

Wear From 

Wire 

DWV, 

No. 

Failed 

Slip at 

100 

Hrs? 

Wear From 

Clamps

Wear From 

Plate 

12 64 L,M Y N M 88 L Y L N 3 0.313 0.258 0.055 69 L,M Y N L 93 M N L M 4 0.313 0.269 0.044 66 M Y M L 90 L N L N 5 0.313 0.255 0.058 6 0.313 0.297 0.016 7 0.375 0.333 0.042 68 L Y L N 92 L N L M 9 0.375 0.364 0.011 

10 0.375 0.375 0 50 L Y M N 74 L Y L N 11 0.313 0.255 0.058 

Wire Code 4 Group IIF Fluid Group IIM Metal 

With 

Code 

Clamp 

Diameter 

Bundle 

Diameter 

Diameter 

Difference Bundle 

Wear From 

Wire 

DWV, 

No. 

Failed 

Slip at 

100 

Hrs? 

Wear From 

Clamps

Wear From 

Plate Bundle 

Wear From 

Wire 

DWV, 

No. 

Failed 

Slip at 

100 

Hrs? 

Wear From 

Clamps

Wear From 

Plate 

1 63 N N N M 87 N,L N N N 2 54 N N L N 78 N Y N N 3 66 N Y N L 90 N,L N N N 4 0.313 0.28 0.033 65 N Y N N 89 N N N N 5 0.313 0.266 0.047 

C-20

67 0.438 0.394 0.044 58 N N N N 82 N,L Y N N 9 0.375 0.375 0 70 N N N N 94 N,L N N N 

10 0.313 0.266 0.047 67 N Y N N 91 L Y N N 11 0.313 0.266 0.047 55 N Y N L 79 L Y N N 

Key: 

N = No N = None M = Moderate Y = Yes L = Low S = Severe 
TABLE C-12. GROUP II SUMMARY OF RESULTS BY WIRE TYPE (Continued) 

Wire Code 7 Group IIF Fluid Group IIM Metal 

With 

Code 

Clamp 

Diameter 

Bundle 

Diameter 

Diameter 

Difference Bundle 

Wear From 

Wire 

DWV, 

No. 

Failed 

Slip at 

100 

Hrs? 

Wear From 

Clamps

Wear From 

Plate Bundle 

Wear From 

Wire 

DWV, 

No. 

Failed 

Slip at 

100 

Hrs? 

Wear From 

Clamps

Wear From 

Plate 

1 49 N,L Y N N 73 N,L N L L 2 56 L Y L L 80 N Y N N 3 68 N Y N N 92 N,L N L M 4 58 N N N N 82 N,L Y N N 567 0.438 0.409 0.029 61 N Y L M 85 N,L Y M L 9 0.5 0.44 0.06 

10 0.375 0.331 0.044 53 N,L Y L L 77 N,L Y N N 11 0.375 0.331 0.044 

Wire Code 9 Group IIF Fluid Group IIM Metal 

With 

Code 

Clamp 

Diameter 

Bundle 

Diameter 

Diameter 

Difference Bundle 

Wear From 

Wire 

DWV, 

No. 

Failed 

Slip at 

100 

Hrs? 

Wear From 

Clamps

Wear From 

Plate Bundle 

Wear From 

Wire 

DWV, 

No. 

Failed 

Slip at 

100 

Hrs? 

Wear From 

Clamps

Wear From 

Plate 

C-21

1234 70 L,N N N L 94 N,L N N L 5679 0.5 0.47 0.03 60 M Y L L 84 N,L 2 Y S L 

10 0.375 0.361 0.014 51 N N N M 75 N,L N N L 11 0.375 0.361 0.014 

Key: 

N = No N = None M = Moderate Y = Yes L = Low S = Severe 
TABLE C-12. GROUP II SUMMARY OF RESULTS BY WIRE TYPE (Continued) 

Wire Code 10 Group IIF Fluid Group IIM Metal 

With 

Code 

Clamp 

Diameter 

Bundle 

Diameter 

Diameter 

Difference Bundle 

Wear From 

Wire 

DWV, 

No. 

Failed 

Slip at 

100 

Hrs? 

Wear From 

Clamps

Wear From 

Plate Bundle 

Wear From 

Wire 

DWV, 

No. 

Failed 

Slip at 

100 

Hrs? 

Wear From 

Clamps

Wear From 

Plate 

12 57 N Y L N 81 N Y N M 3 50 L 3 Y S L 74 N Y L L 4 67 N Y L N 91 N Y L N 567 53 N Y N L 77 N,L Y N L 9 51 N N N L 75 N N N N 

10 0.313 0.252 0.061 62 N Y N S 86 N,L Y M N 11 0.313 0.252 0.061 71 L,N Y N L 95 N,L 1 Y N L 

Wire Code 11 Group IIF Fluid Group IIM Metal 

With 

Code 

Clamp 

Diameter 

Bundle 

Diameter 

Diameter 

Difference Bundle 

Wear From 

Wire 

DWV, 

No. 

Failed 

Slip at 

100 

Hrs? 

Wear From 

Clamps

Wear From 

Plate Bundle 

Wear From 

Wire 

DWV, 

No. 

Failed 

Slip at 

100 

Hrs? 

Wear From 

Clamps

Wear From 

Plate 

C-22

1234 55 N,L Y L L 79 L Y N N 5679

10 71 L,N Y N N 95 N,L Y N N 11 0.313 0.252 0.061 59 N Y N M 83 N Y N M 

Key: 

N = No N = None M = Moderate Y = Yes L = Low S = Severe 
TABLE C-13. WIRE CRUSH TEST RESULTS 

Wire Damage Rating Load Applied 

(lb) Top Wire Code 

Bottom 

Wire Code 

Wire 

Code Most 

Damaged Top Bottom 

80 7 4 7 1 1 

120 7 2 1 

80 1 7 7 0 1 

120 7 0 2 

80 3 10 3 1 1 

120 3 2 1 

80 9 10 10 0 1 

120 10 0 1 

80 2 2 B2 1 1 

120 B2 1 1 

80 10 7 7 0 2 

120 7 1 2 

80 4 2 4 1 0 

120 4 2 1 

80 11 4 4 1 1 

120 4 1 2 

80 7 2 7 2 0 

120 7 2 0 

80 10 2 10 1 1 

120 10 2 1 

80 11 11 2 2 

120 2 2 

80 9 9 0 1 

120 T9 0 1 

80 7 7 1 1 

120 1 1 

80 10 10 1 1 

120 2 2 

80 4 1 4 1 0 

120 4 1 1 

80 3 2 3 2 0 

120 3 2 1 

80 4 4 1 1 

120 1 1 

80 4 3 3 1 1 

120 3 1 2 

80 10 4 4 1 1 

120 4 1 1 

C-23
TABLE C-13. WIRE CRUSH TEST RESULTS (Continued) 

Wire Damage Rating Load Applied 

(lb) Top Wire Code 

Bottom 

Wire Code 

Wire 

Code Most 

Damaged Top Bottom 

80 7 3 7 1 1 

120 7 2 1 

80 3 3 1 1 

120 2 2 

80 9 4 4 0 1 

120 4 1 2 

80 11 10 11 2 2 

120 11 2 2 

80 1 1 1 1 

120 1 1 

* Wire Damage Ratings 

0 – No damage 

1 – Partially through insulation 

2 – Completely through insulation to conductor 

3 – Through conductor 

C-24
APPENDIX D—ADDITIONAL PHOTOGRAPHIC DOCUMENTATION

FIGURE D-1. SEVERE WIRE WEAR 

FROM CLAMP IN GROUP I PTFE WIRE 

NONMIXED BUNDLE 

FIGURE D-2. SEVERE WEAR OF PTFE 

AND PTFE/GLASS WIRES FROM 

CLAMP IN GROUP I 

FIGURE D-3. SEVERE WEAR OF 

PTFE/GLASS WIRE FROM CLAMP IN 

NONMIXED GROUP I BUNDLE 

FIGURE D-4. SEVERE WEAR OF 

MF-PTFE WIRE FROM CLAMP IN 

GROUP I NONMIXED BUNDLE 

FIGURE D-5. SEVERE WEAR OF 

PTFE/GLASS AND MF-PTFE WIRES 

FROM CLAMP IN GROUP I 

FIGURE D-6. MODERATE WEAR OF 

PI/PTFE ALLOY FROM CLAMP IN 

GROUP I NONMIXED BUNDLE 

D-1
FIGURE D-7. MODERATE WEAR 

OF PI/PTFE ALLOY FROM 

CLAMP WHEN MIXED WITH 

XLETFE IN GROUP I 

FIGURE D-8. MODERATE WEAR OF 

PI/PTFE FROM CLAMP IN GROUP I 

BUNDLE MIXED WITH MF-PTFE 

FIGURE D-9. SEVERE WEAR OF 

XLETFE ALLOY WIRE FROM 

PLATE IN GROUP I 

NONMIXED BUNDLE 

FIGURE D-10. MODERATE WIRE-TOWIRE WEAR ON XPI WIRE 

WHEN MIXED WITH XLETFE 

GROUP IIF BUNDLE 

FIGURE D-11. MODERATE WIRETO-WIRE WEAR ON PTFE/GLASS 

IN NONMIXED GROUP IIF BUNDLE

FIGURE D-12. XPI WIRE DAMAGED 

FROM PI/PTFE WIRE IN THE 

80-POUND CRUSH TEST 

D-2 
FIGURE D-13. PI/PTFE WIRE 

DAMAGED FROM PI WIRE IN 

THE 80-POUND CRUSH TEST 

FIGURE D-14. TEST BUNDLES 

MOUNTED ON VIBRATION 

FIXTURES 

FIGURE D-15. FIXTURES MOUNTED 

ON VIBRATION TABLE 

D-3/D-4