Letter Mail Controlled 4/21/2003 4:53:44 PM MC# 2030213: - From Marion C. Blakey, Administrator: The following is an update on the EAPAS program. The enhancements developed as part of the FAA’s EAPAS program specifically related to the issues identified in this safety recommendation are addressed by the Aging Transport Non-Structural Systems
Plan Tasks 3,4, and 5 described in detail below:
Task 3. Enhance airplane maintenance to better address aging airplane svstems. This task involves developing improvements to maintenance programs, training programs, and maintenance documentation to provide the needed focus on and awareness of the issues regarding aging systems. Following are the major components of this task. L Improve inspection criteria for wiring.
Define acceptance criteria for corrosion on flight control actuators and associated linkages, and for hydraulic fittings. Revise the Air Transportation Association (ATA) Maintenance Steering Group (MSG)-3 process to address catastrophic events associated with wire failures as MSG-3 review items. Identify maintenance tasks and inspection intervals for wire failures with catastrophic consequences.
Establish a means to minimize contamination of wiring from metal shavings.
Review air carrier and repair station inspection and repair training programs to ensure that
they adequately address aging wiring system components (wire, connectors, brackets,
shielding, clamps, grounds).
Develop guidance material to address electromagnetic compatibility, lightning, and high
intensity radiated field protection features in the maintenance programs.
Review and update Chapter 20, “Standard Practices for Wiring.”
The above components were assigned to the ATSRAC and were accomplished by task groups
for maintenance, standard wiring practices, and training.
The Maintenance Task Group developed a process to enhance existing maintenance programs
for systems for inclusion in the MSG-3 guidelines, which establishes the baseline for
maintenance programs. The task group, whose members represented major manufacturers
and operators, worked closely with the MSG-3 Working Group to develop this new process
called the "Enhanced Zonal Analysis Procedure." The Performance of the Enhanced Zonal
Analysis Procedure consists of:
l Zonal analysis (traditional MSG-3 logic).
L An enhanced logic and procedure that address wiring and consists of:
- identifying cleaning and inspection tasks that reduce the likelihood of combustible
- a wiring task definition (inspection-level definition, verification of inspection level,
and definition of interval).
This task group also clarified definitions and expectations of general visual inspection criteria
and developed recommendations to minimize contamination and accidental damage to wiring.
The ATSRAC Maintenance Task Group strongly believes that the adoption of the
recommendations developed through its activity will lead to a significant improvement in:
l the attention paid to wiring during maintenance program development;
l the quality of the guidance material supporting scheduled inspections;
l the scope of inspections and consistency of the application of those inspections;
l standard practices to minimize wiring contamination and accidental damage; and
l the awareness of the importance of good housekeeping.
The FAA will propose the adoption of Operations Specifications (OpSpecs) that would require operators to add Aging Wiring System Maintenance Training into their systems. These OpSpecs will support and implement the EAPAS final rule. The FAA will produce guidance material that describes the Enhanced Zonal Inspection
Program using the Enhanced Zonal Analysis Procedure.
The ATSRAC Maintenance Task Group also established a means to minimize contamination of wiring from metal shavings through scheduled maintenance tasks and improvement of maintenance practices. The FAA has requested airplane manufacturers, operators, and supplemental type certificate holders to include specific instructions in service bulletins and engineering orders to take necessary actions to minimize contamination of wiring from metal shavings and other maintenance-related damage.
The ATSRAC Training Task Group developed an advisory circular containing curriculum and lesson plans to address inspection and repair of aging wiring system components that are intended to be incorporated into manufacturer, operator, and repair station training programs. The curriculum and lesson plans were designed following feedback from two surveys of industry. The curriculum and lesson plans take into account the results of the Non-Intrusive Inspection Program, the Intrusive Inspection Program, the Maintenance Task Group, the
Standard Wiring Practices Task Group, and ATA Specification 117 (Wiring Maintenance Practices/Guidelines). The Training Task Group is accomplishing the training portion of the tasking for the Standard Wiring Practices Task Group.
The curriculum and lesson plans for air carrier and repair station inspection and repair training programs ensure that aging wiring system components (wire, connectors, brackets, shielding, clamps, and grounds) are adequately addressed. The FAA will develop rulemaking to require updates to air carrier and repair station training programs to include the intent of the curriculum and lesson plans. The FAA will also develop guidance material that supports the rulemaking effort.
In support of the short-range actions identified in the EAPAS Implementation Plan published in August 2001, the FAA’s Flight Standards Service will develop OpSpecs that require the addition of aging systems maintenance and training programs to support and implement the EAPAS final rule. Most ATA member airlines have already begun incorporating ATA Specification 117, Wiring Maintenance Practices/Guidelines, into their training programs. Additionally, the following improvements have been developed as part of EAPAS l In a proactive approach to increase awareness of wire installation and separation requirements and to deal with general issues of wiring maintenance practices, the FAA produced two training aids. An S-hour aviation video training course, entitled "Aircraft Wiring Practices," was developed for FAA engineers, designated engineering
representatives, aviation safety inspectors, and principal inspectors. The FAA also produced an intemet-based job aid entitled, "Aircraft Wiring Practices (Job Aid)," which is available to everyone dealing with wire installation issues. The job aid can be found at http://www.academy.jccbi.gov/AIRDL/wiringcourse.
L The FAA published a policy statement (ANM-01-04 dated July 2, 2001) entitled "System Wiring Policy for Certification." The policy statement addresses wire installation drawings, safety analyses of wiring and wire bundles, and continued airworthiness considerations for wiring. In the policy statement, the FAA outlined requirements for improving installation drawings so that installers obtain an unambiguous definition of
airplane wiring configurations. Modifiers to the original airplane manufacturer’s wiring system should demonstrate that installation specifications and routing practices for the wiring used is either the same as, or compatible with, originally approved standards. Specifically, wiring separation, wire types, wire bundle sizes, brackets, and clamping should be consistent with the original manufacturer’s approved standards.
Task 4. Add aging systems tasks to the aging airplane research program. This task involves developing specific research and development programs for aging electrical systems and aging mechanical systems that support the objectives of the EAPAS. The research and development programs have been developed with the assistance of the FAA Technical Community Representation Groups for aging electrical and mechanical systems. These programs take advantage of various findings of the ATSRAC. Actions and additional
research and development tasks needed to meet the objectives of the EAPAS are discussed below.
The following subtasks were identified in the original Aging Transport Non-Structural Systems Plan:
Determine if a service life for airplane wire is appropriate. If appropriate, establish the
service life of all types of airplane wire used in transport airplanes.
Establish the condition of aging system wiring components and validate the adequacy of visual inspections.
L Develop nondestructive testing tools for inspection of wiring systems.
L Establish aging effects on aircraft lightning and high intensity radiated field protection systems.
L Develop arc fault circuit breakers.
L Conduct destructive testing of flight control linkages
Since the original Aging Transport Non-Structural Systems Plan was published in 1998, research and development programs that address the original subtasks have been identified. New subtasks have been identified to address issues encountered during the initial 2 years of investigation. The major components of the research and development program for aircraft wiring are:
l Characterization of wire degradation in the aging process;
l Establishment of the condition of aging wiring components based on laboratory analysis and testing;
l Effects of related and unrelated maintenance operations on aircraft wiring;
l Establishment of the condition of aging circuit protection components based on laboratory analysis and testing; and
l Effect of mixed wire types on wire degradation.
The outcome of the research programs will likely result in additions and revisions to advisory material and regulations. The data from the Intrusive Inspection Program are being considered in developing rulemaking for maintenance and training programs. When the inspection tools for wiring systems have been fully tested and approved for use in service, maintenance programs may be revised to provide incorporation of these tools into operator and repair station programs. The components of the Arc Fault Circuit Breaker development are:
l Development of 4OOHz arc fault circuit breakers;
l Development of 2%volt arc fault circuit breakers; and
l Development of miniaturized arc fault circuit breakers.
The Society of Automotive Engineers (SAE) is developing a design requirement document for arc fault circuit breakers. The FAA is participating in the development of that document and is in the process of developing an associated advisory circular and technical standard order for arc fault circuit breakers. The SAE specification for Arc Fault Circuit Breakers is nearing completion. The FAA has developed an issue paper that is currently being used for installation of Arc Fault Circuit Breakers on airplanes. As the first step, Arc Fault Circuit
Breakers are currently being certified and installed on airplanes in non-essential systems to gain experience, collect data, and monitor their performance.
The following is a list of additional research and development programs currently underway as part of EAPAS:
l Development of advanced circuit protection devices.
L Core wiring safety technologies. The components of this subtask are:
Validation of wire inspection and test systems;
Risk assessment methods for aircraft wiring;
Performance requirements, test criteria and procedures for aircraft wire; and
Long-term evaluation of environmental effects on in-service wiring.
The airplane mechanical systems are being considered in the aging study. Currently, the FAA, the Joint Airworthiness Authorities, Transport Canada, and the manufacturers of large transport airplanes (Boeing and Airbus), together with a contractor, are studying the effects of aging on mechanical systems. The study includes evaluation of design and maintenance requirements and procedures for the mechanical systems. Physical inspections and destructive tests will also be preformed on the mechanical systems components such as single element, dual path components (as recommended by ATSRAC). The mechanical systems study will be performed in phases. Each phase will concentrate on study of one aircraft mechanical system (e. g. flight control system, hydraulic system, fuel system, etc.). Phase one is currently underway which involves evaluation of Boeing 757 and Airbus A320 control systems and testing of the critical components on aged airplanes
(Beoing 737,747, and A300).
A 2-year contract has been awarded for completion of Phase I, and the FAA expects to complete Phase I by June 30, 2003. Based on lessons learned from Phase I, it is anticipated that evaluation of other systems will be accomplished at a much faster rate. The FAA plans to add small transport airplane mechanical systems to this study.
Task 5. Improve reporting of accident/incident and maintenance actions involving wiring system components. The major components of this task are to: l Establish codes to better identify wiring system component failures and maintenance actions;
l Improve reporting formats of incident/accidents and maintenance data to make the integration and analysis of databases more efficient for assessing aging trends and problems;
l Add additional data to the National Aviation Safety Data Analysis Center databases to better address aging systems; and
Recommend that aging airplane components like wiring, circuit breakers, connectors, pumps, motors, and harnesses that are removed from airplane during maintenance be examined by airline or repair station facilities for safety implications of the failure. ATA has established a new Subchapter 97 for wiring. It is being proposed that Subchapter 97 be used as the second two digits included in the four-digit ATA code in service difficulty
reports whenever the problem identified relates to wiring. The FAA is in the process of developing guidance to identify the use of Subchapter 97, an update of the JASC code, and an addition to zonal codes. In addition, the FAA is also in process of developing an automated service difficulty reporting system that will support trend analysis. As part of this activit, an integrated aging wiring database coupled with an on-line analytical process methodology are being developed that will also be useful in the certification process. The FAA organized an internal rulemaking team to develop an NPRM for all EAPAS regulatory enhancements when the ATSRAC recommendations are received and reviewed by the FAA. The FAA plans to publish the EAPAS NPRM by December 2003. The FAA regularly provides the EAPAS program updates to the ATSRAC public meetings. The Board’s staff participates in these meetings and is aware of FAA’s progress.