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
Number of Aircraft Inspected
% of the Model Fleet
Age Range
Hour Range
Landing (Cycles) Range
Inspections Performed By
AC Model A AC Model B
5
5
5.90%
2.90%
19 to21
11 to 24
4785 to 7835 4130 to 12001
4846 to 5684 3473 to 8558
WG & OEM WG & OEM
AC Model C AC Model D
5
5
0.61%
0.90%
10 to 18
18 to 25
3258 to 8413 7223 to 12408
2682 to 5692 5709 to 9873
WG & OEM WG & OEM
AC Model E AC Model F AC Model G AC Model H Summary
4
5
5
5
39
2.10%
2.10%
1.05%
0.80%
0.6% to 6%
11 to 12
20 to 30
12 to 15
11 to 32
10 to 32
4130 to 8083 8770 to 17389 4271 to 5904 3572 to 13014 3258 to 17389
2746 to 7498 4843 to 8500 2638 to 3389 3187 to 13252 2638 to 13252
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.)
Evaluation Findings % to Specific Model Totals by Appendix A Categories:
Connectors
3.20%
1.90%
5.40%
3.30%
Terminations
2.30%
0.60%
0.30%
6.70%
Installations (General)
80%
79.50%
87%
87%
Wiring Condition
14.40%
18%
7.30%
2.90%
Significant Items
% of Significant Items (73
Items) to All Model (2256
Items) Evaluation Findings
3.24%
1.70%
0
90.50%
7.80%
1.80%
0.40%
86.40%
11.40%
0%
0%
97.40%
2.60%
2.30%
5.50%
80.70%
11.50%
0
73
1.9
2256
58
2.75%
1.99%
84.53%
10.73%
Damaged Clamp
Zone: 310 Aft equipment
compartment below APU
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
Improper installation
Bend radius
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
NBAA Operator Demographics
Operators
3500
3000
W /O MX
W ith MX
2500
2000
2358
1500
1000
500
669
0
1
362
314
2
Aircraft Operated
237
588
>2
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
X 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