EWISEWISElectrical Wiring Interconnect System

Not Just Another Acronym!

Technical CommitteeSpecial Project ATSRAC

What is EWIS?

• All wiring related components connecting LRU’s such as:–Wiring– Cannon Plugs–Modular Blocks– Clamps– Terminal Strips– Etc.

Why the concerns about EWIS?

• History– NTSB, following the TWA 800 accident,

determined that wiring inside a fuel tank developed a short causing an explosion which downed the aircraft.

– Vice Presidential Committee – Gore –Commissioned detailed study be performed on the health of aircraft wiring in regards to aging of an aircraft.

Why the concerns about EWIS?History (cont.)– The FAA in conjunction with regulatory agencies

worldwide and industry developed a focus group to study the potential problem.• ATSRAC (Aging Transport Systems Rulemaking

Advisory Committee)–Originally formed to perform non-intrusive,

intrusive inspections and develop recommendations to the FAA for Large Transport Aircraft. (ADs, SFAR)

• After the Payne Stewart incident, NTSB recommended that all Transport Aircraft be included in ATSRAC study - STA

ATSRAC – HWG10 - STAWIRING EVALUATIONS - Summary• 39 privately owned in-service a/c

–No Safety of Flight Concern–2256 discrepancies–73 of them are considered as significant*

items*Significant items need to be rectified/repaired for

continued airworthiness throughout aircraft operational life

ATSRAC - STAWIRING EVALUATIONS (Cont'd)• No aging issue specific to wire insulation and

conductor were detected• 29 % of discrepancies are inadequate clearance

with structure, racks, equipments• 43 % of discrepancies are bad clamp

conditionning/sizing/spacing• 68 % of significant items are due to inadequate

clearance or bad clamp conditionning: sizing / spacing.

Aircraft Type

Findings Summary AC Model A AC Model B AC Model C AC Model D AC Model E AC Model F AC Model G AC Model H SummaryNumber of Aircraft Inspected 5 5 5 5 4 5 5 5 39

% of the Model Fleet 5.90% 2.90% 0.61% 0.90% 2.10% 2.10% 1.05% 0.80% 0.6% to 6%Age Range 19 to21 11 to 24 10 to 18 18 to 25 11 to 12 20 to 30 12 to 15 11 to 32 10 to 32Hour Range 4785 to 7835 4130 to 12001 3258 to 8413 7223 to 12408 4130 to 8083 8770 to 17389 4271 to 5904 3572 to 13014 3258 to 17389

Landing (Cycles) Range 4846 to 5684 3473 to 8558 2682 to 5692 5709 to 9873 2746 to 7498 4843 to 8500 2638 to 3389 3187 to 13252 2638 to 13252Inspections Performed By WG & OEM WG & OEM WG & OEM WG & OEM WG & OEM WG & OEM OEM WG & OEM WG & OEM

0731.9

225658

Evaluation Findings % to Specific M odel Totals by Appendix A Categories:Connectors 3.20% 1.90% 5.40% 3.30% 1.70% 1.80% 0% 2.30% 2.75%

Terminations 2.30% 0.60% 0.30% 6.70% 0 0.40% 0% 5.50% 1.99%Installations (General) 80% 79.50% 87% 87% 90.50% 86.40% 97.40% 80.70% 84.53%

Wiring Condition 14.40% 18% 7.30% 2.90% 7.80% 11.40% 2.60% 11.50% 10.73%

Significant Items % of Significant Items (73 Items) to All Model (2256

Items) Evaluation Findings3.24%

Findings per AC (Avg.)

Immediate Fleet Wide Safety

Total Findings

Significant ItemsSignificant Items per AC (Avg.)

Damaged Clamp

Zone: 310 Aft equipment compartment below APU

Oxygen line

Installation invertedTeflon shim

Disabled system connectors – pulled from rackTied to environmental system duct

Conduit rubbing on connector hardware

Wires pinched in clamp

Improperly Installed Clamp (pinching wire)

Zone: 140 Under floor area above wing box

Chaffed through

Bend Radius

Zone: 220 Flight compartment above floor behind circuit breaker panel (copilot’s feet)

Bend radius

Improper installation

Installation deterioration and inadequate clearances

Inadequate clearance

Inadequate Clearance to Structure

Zone: 114/115 Flight compartment under floor bottom of fuselage

Damaged Conduit Zone: 143/144 Main landing gear wheel well

Outer Jacket of Power Cable Pulled Back Wires Exposed

Zone: 310 Aft equipment bay (APU compartment)

Improper Repair

Zone: 143/144 Main landing gear wheel well

Debris on Power Wires (Metal Shavings)

Zone: 240/250 Cabin area above floor

Contaminated Wires

Zone: 250 Cabin area above floor near luggage compartment door

ATSRAC – HWG10General Comments - From a/c evaluations

• Aircraft in good overall condition• Reasons of Discrepancies

– Wiring Repair• Training Issues• Lack of use of OAM Standard Practice Manuals

– Routing of Modification Wiring• Training Issues• Lack of use of Industry Standard Guidelines (AC 43.13)

and OAM Standard Practice Manuals

ATSRAC – HWG10General Comments (cont'd)

Clamping and Structural Contact– Training Issues– Instructions for Continued Airworthiness Issues

• “Protect, Clean as you go” philosophy– Training Issue– ICA – possible no mention

• Industry cultural concerns

Aircraft Maintenance Program Philosophy– STA = OEMs Develops and Maintains

Maintenance Programs – FAA approves Chapter 4/5 and accepts Mx Manuals (ICAs)

• Owner/Operator typically follows OEM Recommendations

– STA = Owner/Operator to # Aircraft - 1 to 1.4• Each Aircraft is Very Unique as each owner• Avionics Packages vary from aircraft to aircraft• Corporate Interiors and the associated wiring vary

from aircraft to aircraft

ATSRAC – HWG10

ATSRAC – HWG10

Organizational Differences– STA = Smaller Organizations within each

Department • Dispatch• Flight• Maintenance (35%)

– STA Owner/Operators tend to be more interdependent with TC and STC Holders

NBAA Operator Demographics

669

2358

314362

588

237

0

500

1000

1500

2000

2500

3000

3500

1 2 >2

W/O MXWith MX

Operators

Aircraft Operated

ATSRAC – HWG10Lessons Learned

• Before April of 2002 the Majority of the Working Group was not Aware of EWIS -Concepts

• Based on the review of:– Aircraft Evaluations– Service History/ADs– Intrusive Inspection Report– HWG-6 through HWG-9 Final Reports

ATSRAC – HWG10Lessons Learned

• HWG-10 determined areas of need:– Awareness and Training– Installation Guidance (FAA driven –

Standardization Issues)– Inspection Criteria– Maintenance Procedures– Enforcement of Current Regulations

HWG-10 RecommendedFAA and industry implement an “EWIS

Awareness” program to effect cultural change

Rationale– The aircraft evaluations support the need for TC

and STC holders, approvers, designers, installers, and technicians to become more aware of the concepts of EWIS during design, certification, installation and maintenance. HWG-10 feels that the current regulations with slight modifications are adequate if properly communicated and enforced.

HWG-10 RecommendationsFAA• FAR Part 147 Appendix E is revised to

include the concepts of AC 120-YY (EWIS, Detailed Inspection (DET), General Visual Inspection (GVI), and Special Detailed Inspection (SDI)).

RationaleTo fully effect a culture change, in the aviation industry, this should include a “ground up” approach (e.g. future technicians are trained from day one on EWIS concepts)

HWG-10 RecommendationsFAA• The following Advisory Circulars be revised

to include EWIS concepts:– 43.13– 43.204– 65-9A– 65-11B– 65-12A– 65-15A* concepts and language with standardized criteria for

EWIS

HWG-10 Recommendations

Rationale– These Advisory Circulars are the basis for

certification, maintenance, and training of industry personnel.

– “EWIS” concepts revision would generate awareness to a large group of existing and future approvers, designers, installers, and technicians.

Installation Guidelines/Criteria

Standardization - Installation Guidelines must be FAA/Industry driven– Currently, Installation Guidance is based off of:

• AC43.13 – Outdated Needs to Be Revised to Latest Technologies

– Current Non-Turbine Powered Aircraft have more technology than AC can support

• ATA Spec 117• ANM-104 – Created Confusion throughout ACOs and

subsequently industry

Inspection Criteria

Rationale• There is a lack of Inspection Criteria for

wiring and its subcomponents.• Development of this Criteria will ensure

that inspectors know what is to be inspected.

Maintenance ProceduresRecommendations • Review existing manufacturer

inspection/maintenance programs and enhance for EWIS considerations

• Manufacturer standards - wiring practices – pass fail criteria

• Training program

Maintenance Procedures

OEMs and STC Holders to enhance the current Maintenance Procedures– Enhancement doesn’t necessarily drive to

EZAP.• Maintenance Program Development

Philosophies of the Various STA OEMs should be capable of enhancing current programs incorporating concepts of EWIS

• Future Small Transport Aircraft Designs will most likely follow the version of MSG-3 of that time period or applicable analytical logic process of that time period.

ATSRAC - STA

What’s next?HWG 13 New Tasks - further define and develop for STA

Criteria for enhanced wiring inspection proceduresMeans of compliance

So now we know…

• Installation of wiring (EWIS) has not had the awareness of the Approvers & Maintainers it requires

• Concerns for installation & functionality of equipment was the priority – not wiring

• Current practices will not be allowed to continue as is

Future - demands an EWIS priority…

• Communicate through existing industry venues and forums available (i.e. AEA, GAMA, PAMA, NBAA…) and through FAA and state DOT sponsored activities (i.e. D.E.R renewals, IA renewal…)

Future - demands an EWIS priority…• Enhance Maintenance Procedures –

Instructions for Continuous Airworthiness –both TC and STC Holders

• Enhancement of Advisory Material both Current and Future Development of EWIS Installation Guidance

• Inspection Criteria – Pass/Fail Inspection Criteria for go/no-go decisions

EWIS Reference Information

• Websites– Official ATSRAC Website:• www.mitrecaasd.org/atsrac/index.html

– FAA Wiring Training Website:• www.academy.jccbi.gov/AIRDL/wiringcourse

Thank You!Thank You!Eli Cotti

Ecotti@nbaa.org

Questions?Questions?