New FAA Rule Boosts Aircraft Wiring Safety

The Federal Aviation Administration (FAA) completed a new rule designed to mitigate conditions that put airliners at risk for wire failures, smoke and fire. The final rule greatly enhances the safety requirements for design, installation and maintenance of electrical wiring in new and existing airplane...

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The Federal Aviation Administration (FAA) completed a new rule designed to mitigate conditions that put airliners at risk for wire failures, smoke and fire. The final rule greatly enhances the safety requirements for design, installation and maintenance of electrical wiring in new and existing airplane designs, said the agency, adding it moves existing rules on wiring into a single section of the regulations, and adds new certification standards to address wire degradation and inadequate design or maintenance. The action stems from the 1996 TWA crash in which the fuel tank exploded and a 1998 SAS MD-11 crash off the Canadian coast. The two accidents killed 459 passengers.
This final rule is a result of recommendations made by industry groups working with the FAA and international authorities. The new maintenance requirements apply to aircraft carrying more than 30 passengers or having a maximum payload of 7,500 pounds or more. The estimated total cost of this final rule is $416 million ($233 million present value) over 25 years.
The rule is part of a broader FAA effort to improve the safety of a variety of aircraft systems, including wiring. The program looked at how connectors, wiring harnesses and cables were installed and how they degraded during an aircraft’s service.
Under the rule, manufacturers must complete FAA-approved instructions for new wiring-related maintenance and inspection tasks within 24 months of the effective date for existing airplanes. U.S. scheduled air carriers and foreign airlines operating U.S.-registered aircraft must develop maintenance and inspection programs for wiring based on the manufacturers’ instructions within 39 months of the effective date, and update those programs as needed for subsequent aircraft modifications.
The FAA’s Enhanced Airworthiness Program for Airplane Systems (EAPAS), which was established in 2001, has been developing enhancements for continued safety of aircraft wiring systems from their design, installation, and maintenance throughout their operational life.
The EAPAS program led to a proposed rule in October 2005 that, for the first time, viewed aircraft wiring as important systems on their own. The rule proposed to revise current maintenance practices and specified other actions to address issues of aging and degradation in wiring.
The final rule, comprehensive in addressing all aspects of electrical wiring design, installation and maintenance for transport airplanes, was published on November 8, 2007.
The final rule makes regulatory changes pertaining to wiring systems and fuel tank systems in transport category airplanes. The rule:
• Requires manufacturers to conduct analyses and develop Instructions for Continued Airworthiness (ICA) for wiring to improve maintenance procedures for wire systems.
• Requires operators to incorporate ICA for wiring into their maintenance or inspection programs.
• Clarifies requirements of certain existing rules for operators to incorporate ICA for fuel tank systems into their maintenance or inspection programs.
The effort is also developing certification and maintenance instructions for airplane wiring as part of a new subpart of Part 25 specifically devoted to wiring. The applicants of pending Supplemental Type Certificates (STC) and existing Type Certificate (TC) holders for transport airplanes will provide ICA that incorporates all the TC holder variations of wire systems used on that series.
ICA for wiring for existing airplanes must be completed by 24 months after the effective date of the rule on December 10, 2007.
Applicants for approval of future design changes to affected transport airplanes must evaluate effects of proposed changes on the wiring ICA developed by the TC holder and develop revisions to the ICA to address those effects.
ICA prepared in compliance with SFAR 88 will be reviewed to ensure compatibility with and avoid duplication of the new ICA for wiring.
Operators under parts 121 and 129 will incorporate the wiring ICA in their maintenance/inspection programs by 39 months after the effective date of the rule, and update those programs as needed for subsequent modifications.
By December 16, 2008, operators under Parts 91, 121, 125, and 129 will develop maintenance/inspection programs for fuel tank systems based on fuel tank system ICA developed by manufacturers under SFAR 88. There are fewer than 20 such airplanes operating under part 135, so the FAA did not include them.