Regulatory Report

FAA Issues Huge Wiring NPRM

On October 6, the FAA issued a notice of proposed rulemaking (NPRM) that could have profound effects on manufacturers and operators of transport-category aircraft. On the same day, the FAA also released 12 draft advisory circulars covering wiring issues, to provide guidance to operators on wiring maintenance and safety practices. To find the documents, go to the Federal Register website for October 6 (www.access.gpo.gov/su_docs/fedreg/a051006c.html) and scroll to the Federal Aviation Administration section.

"The intent of this proposal," stated the summary of the NPRM, "is to help ensure the continued safety of commercial airplanes by improving the design, installation, and maintenance of their electrical wiring systems as well as by aligning those requirements as closely as possible with the requirements for fuel tank system safety."

Aviation industry personnel are invited to comment on the NPRM by February 3, 2006. Given the scope of the proposed regulations, it seems likely that industry associations will ask for more time to evaluate the material and develop reasoned comments.

The NPRM cites the TWA Flight 800 fuel-tank explosion and the Swissair MD-11 crash in the Atlantic Ocean as wiring-related. "Investigations of those accidents," the NPRM stated, "and subsequent examinations of other airplanes showed the deteriorated wiring, corrosion, improper wire installation and repairs, and contamination of wire bundles with metal shavings, dust, and fluids, which would provide fuel for fire, were common conditions in representative examples of the `aging fleet of air transport airplanes.'"

Due to what the FAA concluded are inadequate wiring maintenance practices, the NPRM is proposing "new maintenance, inspection, and design criteria for airplane wiring to address conditions that put transport airplanes at risk of wire failures, smoke, and fire." Type certificate holders and applicants for type certificates and supplemental type certificates would be required to analyze aircraft for zones where wire is present and likelihood of contaminants; develop maintenance and inspection tasks to make sure wiring doesn't risk safe flight; develop new instructions for continued airworthiness for wiring and incorporate these, including fuel tank continued airworthiness, in regular maintenance programs.