Presented by Stephen Slotte FAA Transport Standards Staff FAA 2nd Annual EAPAS Conference Certification and Implementation of Airborne Arc Fault Circuit Breakers Presented by Stephen Slotte FAA Transport Standards Staff

Background Aging Systems R,E & D FAA R,E,&D Intrusive Inspections Arc Fault Circuit Breaker Development Interconnect System Testing and Assessment Inspection and Testing Technology Development Aging Systems R,E & D The following programs are some of the R,E&D programs currently in progress: Intrusive Inspections Validated Non- Intrusive Inspections and Methods Assess any physical degradation of wiring Arc Fault Circuit Breakers Development of a circuit interrupter that will remove power if an arcing event is detected Direct replacement for existing circuit breakers Development of wire test and inspection systems

Background: Arc Faults Present aircraft circuit breakers are designed to protect against overloads and short circuits. Arcing faults draw less current than hard faults and are intermittent in duration. Arcing faults can cause systems failures and fires. Present aircraft are equipped with traditional thermal circuit breakers which do not provide protection against many types of intermittent types of wiring faults that produce arcing. Thermal circuit breakers will only open if the circuit draws enough current for a given period of time. Most wiring faults are intermittent such that the thermal circuit breaker current-time requirements are not met. Arc Fault Circuit Breakers (AFCB) have circuitry which can detect the typical intermittent type of wiring arcing fault. Service history indicates that arcing faults often lead to systems failures and wiring related smoke and fire incidents.

Background: Wire Degradation Wiring insulation degradation increases with time due to a variety of reasons such as: Chaffing Environmental stresses Maintenance. Service history data has shown that wiring insulation degrades due to a variety of reasons such as chafing, environmental stresses, and maintenance. The degree of degradation varies depending of the wiring system design, the type of maintenance procedures, and operational differences. Degradation varies due to design, maintenance, and operational differences

During flight the crew had to cut into this ceiling area to put fire out. BAGGAGE BINS ABOVE ROW 6 & 7

Background: Current Inspection Technology Current inspection and surveillance methods for aircraft wiring are limited in effectiveness and periodic in frequency. Arc Fault Circuit Breakers provide continuous protection. Arc Fault Circuit Breakers have the potential to provide continuous protection of wiring against the types of wiring faults that are normally not detected due to the limited effectiveness of current thermal circuit breakers and the limited effectiveness of periodic maintenance.

FAA Approach Develop certification criteria compatible and in parallel with SAE activity TSO, based on SAE developed AFCB Specification Installation Advisory Circular Be ready to issue TSO and AC at the completion of initial SAE activity scheduled for January, 2003 The FAA realizes the tremendous safety potential of AFCBs and has developed a strategy along with industry stakeholders to facilitate the implementation or airborne AFCB. The Society of Automotive Engineers (SAE) AE8B Committee has been tasked to develop technical performance specification for airborne AFCBs. The FAA is participating in the SAE AE8B activity to ensure that AFCB technology and aircraft installation issues are adequately addressed in a timely manner to support the development of an FAA AFCB Technical Standard Order (TSO) and installation Advisory Circular.

Realities of New Technologies The FAA is committed to expedite airborne AFCB technology. However... Learning curve associated with certification of new technology Expect initial projects to be scrutinized more than a standard STC Initial AFCB projects by Issue Paper process There are still some difficult technology issues to resolve prior to widespread installation on aircraft, but the FAA along with AFCB manufacturers and aircraft manufacturers, have stepped forward in addressing these issues and are collectively pursuing an aggressive development and test schedule to resolve the technology issues, develop certification criteria, and introduce the AFCBs into transport aircraft. FAA’s Process for developing and issuing Issue Papers: The FAA must evaluate new airborne technologies and develop appropriate certification criteria. When new devices are analyzed, the FAA must provide applicants a standardized set of certification concerns to be addressed. The FAA uses the Issue Paper process to document the means of compliance for new technologies and/or new devices. The Issue Paper is fully coordinated with the Applicant and the FAA. This Issue Paper coordination process can take some additional time so careful planning is required by all stakeholders.

Major Installation Issues Common Causes of Nuisance Trips Load Characteristics Crosstalk (e.g.EMI, Lightning, adjacent wiring) Feedback (parallel circuits) Fault Masking Algorithm Dependent Post Trip Maintenance May need NDT in addition to visual

Current Status Current FAA certification of AFCBs for non-essential circuits SAE AFCB specification nearing completion TSO and AC in development Issue Papers Project Specific Document means of compliance until TSO and AC published For AFCB devices the FAA will use the Issue Paper process until the TSO and AC are completed after first phase SAE specification is completed which is currently scheduled for November, 2001. The Issue Paper is currently in Stage 2 coordination, which means that the FAA position is currently being solidified. It is expected that the SAE specification will be referenced directly by the TSO such that the SAE specification will contain all the necessary AFCB device level certification requirements. The AC will address installation unique certification requirements such as aircraft level test requirements and installation safety assessment requirements. The AC will derive most of its content directly from the Issue Paper which is currently in coordination.

AFCB Issue Paper Underlying Certification Philosophy Provide a path for manufacturers to install AFCBs on a non-interference basis for purposes of gathering data Limit AFCB installation to non-essential systems until adequate service history data can demonstrate proper function and reliability Limit AFCB installation on critical circuits such that continued safe flight and landing can be achieved given an assumed common-mode nuisance trip

AFCBs- Summary Potential benefits Possible risks Protection against internal wire bundle arc fault damage Minimize wiring related smoke and fire incidents Minimize common mode wire bundle failures Possible risks Nuisance trips Post trip diagnosis issues

Point of Contact Brett Portwood Los Angeles ACO 3960 Paramount Boulevard ANM-130L Lakewood, CA 90712 562.627.5350 brett.portwood@faa.gov