FAA Tackles Aircraft Wiring

 - May 15, 2008, 9:38 AM

Prompted in part by NTSB recommendations arising from the July 1996 crash of TWA Flight 800 off Long Island, the FAA has developed an enhanced airworthiness program for airplane systems (EAPAS) to increase awareness of wiring system degradation and improve both maintenance and design of electrical systems.

In addition to issuing corrective actions such as ADs, the agency’s near-term actions include fostering better wiring maintenance procedures through a “lessons learned” document from aircraft manufacturers to operators, new training and guidance materials for FAA inspectors and engineers and sharing information with industry and worldwide civil aviation authorities.

Longer-term actions in the EAPAS plan are intended to “institutionalize” management of aircraft wiring systems by revising existing federal regulations concerning design, certification, maintenance and continued airworthiness of aircraft wiring systems.

This effort would include:

• Proposing a Special Federal Aviation Regulation (SFAR) to mandate the development of an enhanced inspection program.

• Proposing regulatory changes to enhance maintenance programs for systems.

• Developing advisory materials that define an aging systems maintenance and training program.

• Proposing changes to certification regulations to specifically address wiring systems.
Other longer-term actions will improve reporting and analysis of wire problems and foster research and development in the areas of arc-fault circuit breakers, automated wire inspection tools, wire separation and wire performance.

The FAA based its EAPAS plan on results from an intensive data-gathering effort on aircraft wiring systems done in cooperation with industry. It is part of the FAA’s overall aging transport nonstructural systems program, an effort begun in October 1998, which itself is an expansion of the agency’s aging aircraft program.

The systems program, modeled after the “very successful” aging structures program started more than a decade ago, looks into wiring systems–such as connectors, wiring harnesses and cables–and is now reviewing mechanical systems.

FAA Administrator Jane Garvey created a formal advisory group called the Aging Transport Systems Rulemaking Advisory Committee (ATSRAC) in 1999. It is made up of representatives from aircraft manufacturers, airlines, user groups, aerospace and industry associations and government agencies.

Under ATSRAC auspices, a series of data-gathering efforts studied both in-service and retired commercial airliners in the first systematic effort to look at the state of aircraft wiring. The data showed that wire degradation and failure could have multiple causes, and these problems were not solely related to age. ATSRAC synthesized the data and made recommendations to the FAA last January.

EAPAS is the agency’s plan to act on these results and recommendations while simultaneously instituting the agency’s own strategies for improved wire system safety. The near-term parts of the EAPAS plan are designed to accomplish rapid safety improvements based on existing, fully analyzed data, and are mostly complete, according to the FAA.