Transcript EWIS Safety Assessment - Center for Advanced Aviation
WSHWG Development of § 25.1705
WSHWG Meeting No. 9 Bombardier Aerospace Montreal, Quebec Stephen Slotte Task 6.6 Leader 10/6/02
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Boring Acronyms I Use
• ARAC: Aviation Rulemaking Advisory Committee • ESHWG: Electrical Systems Harmonization Working Group • ATSRAC: Aging Transport Systems Rulemaking Advisory Committee • WSHWG: Wire Systems Harmonization Working Group • EWIS: Electrical Wiring Interconnection System 2 nd Annual FAA EAPAS Conference Washington DC November 5-7, 2002
WSWHG & ESWHG Members
• FAA • JAA – CAA, UK – DGAC, France – RLD, Netherlands • Transport Canada • AECMA • ALPA • Airbus • Boeing • Bombardier • British Airways • Cessna • Dassault Aviation • Embraer • Thales Avionics • Tyco Electronics 2 nd Annual FAA EAPAS Conference Washington DC November 5-7, 2002
What We Did
Combine Wire Related FARs/JARs Develop Strategies for Mitigating Effects of Age Develop Wire Safety Assessment Requirements Harmonized Electrical System Requirements New/Revised EWIS Requirements Advisory Material for EWIS Requirements Develop Wire Separation Requirements Develop Wire Identification Requirements Develop Advisory Material 2 nd Annual FAA EAPAS Conference Washington DC November 5-7, 2002
WSHWG Existing, Proposed, & Final FAR/JAR Part 25 Revisions
New FAR/JAR 25 Existing FAR/JAR 25
A
A B C D E F G Proposed Changes D E F G
H B C D E F G H § 25.611
§ 25.1310
§ 25.773
§ 25.1316
§ 25.855
§ 25.1331
§ 25.863 § 25.1351
§ 25.869 § 25.1353
§ 25.899 § 25.1355
§ 25.903 § 25.1357
§ 25.1165 § 25.1360
§ 25.1189 § 25.1362
§ 25.1203 § 25.1365
§ 25.1301 § 25.1431
§ 25.1309 § 25.1529
2 nd Annual FAA EAPAS Conference Washington DC November 5-7, 2002
Some of the Big Hitters
• EWIS: – Definition – System Function and Installation – System Safety – System Separation – System Component Identification – System Power Removal 2 nd Annual FAA EAPAS Conference Washington DC November 5-7, 2002
STC Design & Installation
Seat Track Wiring for IFE In-Service Condition
EWIS As A “System”
• EWIS is more than just wire – Multiple components • Wire • Connectors • Support devices • Etc….
– The multiple components make a whole • Shifting the paradigm about what a system is will raise awareness about the importance that wires and their components have toward producing a safe product
EWIS As A “System”
Aircraft wiring can no longer be thought of as a collection of single wires. It must be considered as integrated whose failures have an airplane level effect.
2 nd Annual FAA EAPAS Conference Washington DC November 5-7, 2002
§
25.1701
*
EWIS Definition
* Proposed to the FAA by the Aging Transport Systems Rulemaking Advisory Committee (Reference ATSRAC Task 6 Final Report to ATSRAC, Document No. WS-50-04)
What is an EWIS?
An electrical wiring interconnection system is defined as an electrical connection between two or more points including the associated termination devices and the necessary means for its installation and identification.
2 nd Annual FAA EAPAS Conference Washington DC November 5-7, 2002
An EWIS Includes:
• Wires & cables • Connections to electrical devices • CBs or other circuit protection devices • Connectors & accessories • Electrical grounding and bonding devices • Electrical splices • Conduits that have electrical termination for the purpose of bonding • Clamps & other devices used to route and support the wire bundle • Cable tie devices • Labels or other means of identification • Pressure seals associated with EWIS 2 nd Annual FAA EAPAS Conference Washington DC November 5-7, 2002
An EWIS Also Includes:
EWIS components inside shelves, panels, rack, junction boxes, distribution panels, back-planes of equipment racks including circuit board back-planes, wire integration units, etc 2 nd Annual FAA EAPAS Conference Washington DC November 5-7, 2002
An EWIS Doesn’t Include:
• Wiring inside avionics equipment • Equipment including non-required miscellaneous equipment qualified to environmental conditions and testing procedures approved by the Administrator other than those specifically included in the definition • Equipment qualified to a technical standard order • Portable, carry-on, or otherwise non permanently mounted electrical equipment • Fiber optics • Mating connection at the termination point of the wire on those devices that are excluded from the EWIS definition
Electrical Wiring Interconnection System
§
25.1703
*
EWIS Function & Installation
* Proposed to the FAA by the Aging Transport Systems Rulemaking Advisory Committee (Reference ATSRAC Task 6 Final Report to ATSRAC, Document No. WS-50-04)
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§ 25.1703 - EWIS System Function & Installation • Similar to § 25.1301 but is broader • Examples: – Minimize • Mechanical strain • Damage by personnel movement • Damage by items carried onto the aircraft by passengers, cabin crew, and flightcrew – Hazardous effects of moisture must be minimized 2 nd Annual FAA EAPAS Conference Washington DC November 5-7, 2002
EWIS System Function & Installation • EWIS modifications to the original type design must be designed and installed to the same standards used by the original aircraft manufacturer or other equivalent standards acceptable to the Administrator 2 nd Annual FAA EAPAS Conference Washington DC November 5-7, 2002
Design & Installation
NTSB Photographs
§
25.1705
*
EWIS System Safety
* Proposed to the FAA by the Aging Transport Systems Rulemaking Advisory Committee (Reference ATSRAC Task 6 Final Report to ATSRAC, Document No. WS-50-04)
Federal Register Tasking
Federal Register/Vol. 66, No. 103, Page 29203, Tuesday, May 29, 2001 • Identify requirements to conduct wire system safety assessments. • Review § 25.1309-1A (or latest revision), corresponding JAR-25 material, and related ARAC recommendations and recommend, if appropriate, particular methods of compliance with § 25.1309 that should be mandated in a new wire system rule .
2 nd Annual FAA EAPAS Conference Washington DC November 5-7, 2002
§ 25.1705: The Rule Objective
Focus attention on EWIS and the safety issues associated with them using the concepts of § 25.1309 and provide a tool to find potential failures early in the design process 2 nd Annual FAA EAPAS Conference Washington DC November 5-7, 2002
Failure Conditions
• § 25.1705 failure conditions – Hazardous – Catastrophic – Same words as § 25.1309
– Same meaning as § 25.1309
• Hazardous must be shown to be extremely remote • Catastrophic must be shown to be extremely improbable 2 nd Annual FAA EAPAS Conference Washington DC November 5-7, 2002
Too Many Splices!
So What is § 25.1705 All About?
• It’s like § 25.1309, but it’s NOT § 25.1309
• The proposed rule language is consistent with § 25.1309
• Requires EWIS to be analyzed for failure conditions that affect airplane level safety 2 nd Annual FAA EAPAS Conference Washington DC November 5-7, 2002
Why This Rule?
• History dictates the need: – Wire related incidents and accidents – Post-TC modifications have proven to be an issue time-and-time again – OEM delivered airplanes have had wiring issues out-the-door or they have developed in-service – Existing safety assessment requirements have not always been applied to wire systems • Inadequate application • Inconsistent application • Existing requirement does not go far enough • Current compliance activity is not sufficient
Why This Rule?
Current § 25.1309 SSA’s typically have not considered “cause” of a wire failure effecting other wires in the EWIS. They look at rotor burst, lightning, hydraulic line rupture, etc. But what about the failure of the EWIS created by a single wire chafing or arcing event taking out other functions supported by the EWIS?
§ 25.1705
Pre & Post TC Safety Analysis Concept • Applies to applicants for pre-TC work and for amended TC’s and STC’s when the applicant is in possession of all pre-modification data for the areas the modification will effect • This means you have to be able to identify the systems in the EWIS under consideration for modification and the system functions associated with that EWIS 2 nd Annual FAA EAPAS Conference Washington DC November 5-7, 2002
§ 25.1705
Post - TC Safety Analysis Concept • Applies to applicants for post-TC modifications where the applicant cannot identify the systems or systems function contained in EWIS under consideration for modification – Airplane manufacturers – Designated Alteration Stations – Other STC or ATC applicants • If you don’t know what’s in the bundle then stay away from it in a manner decided between you and the certifying authority
As Delivered Design and Installation Separation the Thickness of A Credit Card
§
25.1709
*
EWIS System Separation
* Proposed to the FAA by the Aging Transport Systems Rulemaking Advisory Committee (Reference ATSRAC Task 6 Final Report to ATSRAC, Document No. WS-50-04)
New & Expanded Separation Requirements for EWIS • Replaces the wiring separation requirements of § 25.1353
• Adds additional EWIS separation requirements, for example: 2 nd Annual FAA EAPAS Conference Washington DC November 5-7, 2002
New & Expanded Separation Requirements for EWIS • Adds additional EWIS separation requirements, for example: – Fuel system components – Hydraulic system components – Oxygen system components – Waster/waste system components – Flight or other mechanical control system cables and associated components – Heated equipment, hot air ducts, and lines – Redundant systems – Aircraft structure, sharp edges, and corners 2 nd Annual FAA EAPAS Conference Washington DC November 5-7, 2002
STC Design & Installation
New & Expanded Separation Requirements for EWIS • Separation must be achieved by separation distance or barrier. In some cases other means shown to be at least equivalent is allowed.
• NO specific separation distances or equivalent barrier are specified – the applicant must establish them based upon analysis of design and installation of specific features
New & Expanded Separation Requirements for EWIS • Defining an adequate separation distance or equivalent barrier must include: – Electrical characteristics, amount of power and failure condition severity – Installation design features – Maximum amount of wire slack – Probable variations in the EWIS installation – Intended operating environment – Maintenance practices defined in the airplane manufacturers standard wiring practices manual.
– Maximum temperature generated by adjacent wire/wire bundles during normal and fault conditions
STC Design & Installation
§
25.1711
*
EWIS Component Identification
* Proposed to the FAA by the Aging Transport Systems Rulemaking Advisory Committee (Reference ATSRAC Task 6 Final Report to ATSRAC, Document No. WS-50-04)
EWIS Component Identification § 25.1711 will require EWIS components to be labeled or otherwise identified to facilitate its identification, function, operating limitations, or any applicable combination of these factors.
2 nd Annual FAA EAPAS Conference Washington DC November 5-7, 2002
EWIS Component Identification § 25.1711 imposes additional requirements for EWIS components that are required for safe flight, landing, egress, or have the potential to impact the ability of the flightcrew to cope with adverse operating conditions 2 nd Annual FAA EAPAS Conference Washington DC November 5-7, 2002
EWIS Component Identification Post-TC modifications must be identified to the same standards used by the original aircraft manufacturer of other equivalent standards acceptable to the Administrator 2 nd Annual FAA EAPAS Conference Washington DC November 5-7, 2002
EWIS Component Identification • EWIS component identification will help ensure that systems remain safe and operate as intended throughout the service life of the airplane.
• Clear labeling will allow installers, inspectors, and maintainers to readily identify that the correct system components are installed as designed, and allows modifiers to add systems with due regard to the existing protection and separation requirements established by the original airplane manufacturer 2 nd Annual FAA EAPAS Conference Washington DC November 5-7, 2002
Design & Installation
§
25.1720
*
System Power Removal
* Proposed to the FAA by the Aging Transport Systems Rulemaking Advisory Committee (Reference ATSRAC Task 6 Final Report to ATSRAC, Document No. WS-50-04)
§ 25.1720 Requires a Switch
For airplane systems that require the ability to remove or reset power during normal operations the system must be designed such that circuit breakers are not the primary means to remove or reset system power 2 nd Annual FAA EAPAS Conference Washington DC November 5-7, 2002
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