Technical Committee Special Project ATSRAC EWIS Electrical Wiring Interconnect System Not Just Another Acronym!
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 - STA WIRING 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 - STA WIRING 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 Summary Number 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 32 Hour 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 13252 Inspections Performed By WG & OEM WG & OEM WG & OEM WG & OEM WG & OEM WG & OEM OEM WG & OEM WG & OEM Immediate Fleet Wide Safety Significant Items Significant Items per AC (Avg.) Total Findings Findings per AC (Avg.) 0 73 1.9 2256 58 Evaluation Findings % to Specific Model 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 Findings 3.24%
Zone: 310 Aft equipment compartment below APU Damaged Clamp
Oxygen line
Installation inverted Teflon shim
Disabled system connectors pulled from rack Tied to environmental system duct
Conduit rubbing on connector hardware
Wires pinched in clamp
Zone: 140 Under floor area above wing box Improperly Installed Clamp (pinching wire)
Chaffed through
Zone: 220 Flight compartment above floor behind circuit breaker panel (copilot s feet) Bend Radius
Bend radius Improper installation
Installation deterioration and inadequate clearances
Inadequate clearance
Zone: 114/115 Flight compartment under floor bottom of fuselage Inadequate Clearance to Structure
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)
Zone: 143/144 Main landing gear wheel well Improper Repair
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 HWG10 General 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 HWG10 General 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
ATSRAC HWG10 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 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
Operators 3500 NBAA Operator Demographics 3000 2500 W/O MX With MX 2000 2358 1500 1000 500 0 237 669 362 314 588 1 2 >2 Aircraft Operated
ATSRAC HWG10 Lessons 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 HWG10 Lessons 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 Recommended FAA 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 Recommendations FAA 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)). Rationale To 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 Recommendations FAA 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 Procedures Recommendations 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 procedures Means 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
Questions? Thank You! Eli Cotti Ecotti@nbaa.org