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This rulemaking would amend certain airworthiness regulations for transport category airplanes regarding lightning protection of fuel tanks and systems by establishing design requirements for both normal conditions and possible failures of fuel tank structure and systems that could lead to fuel tank explosions, adding new maintenance requirements related to lightning protection features, and imposing specific requirements for airworthiness limitations in the instructions for continued airworthiness. It would also create performance-based standards for prevention of catastrophic fuel vapor ignition caused by lightning by regulating the risk due to both ignition sources and fuel tank flammability. This change would allow designers to take advantage of flammability reduction technologies whose effectiveness was not foreseen when earlier revisions to these rules were written. This change would also relieve some of the administrative burdens created by the current regulations.

Overall Description of Deadline: This rulemaking would establish design requirements for both normal conditions and possible failures of fuel tank structure and systems that could lead to fuel tank explosions, adding new maintenance requirements related to lightning protection features, and imposing specific requirements for airworthiness limitations in the instructions for continued airworthiness.

Statement of Need:

The regulations as currently written to protect fuel tanks from the risk of catastrophic explosion due to lightning strikes is not always practical. The impracticality has led manufacturers to petition for exemptions from this section, which the FAA has granted with special conditions to achieve the intended level of safety of the rule. This exemption process has created an administrative burden on both industry and the FAA. This rulemaking proposes to amend those to remove the requirement for the prevention of lightning ignition sources and add a new, broader requirement for the prevention of ignition due to lightning. This new proposed requirement is intended to mitigate the risk of fuel tank ignition by considering both ignition sources and fuel tank flammability limits offered by existing regulations. The proposed amendments would re-state, in performance-based rules, the intention to prevent catastrophic fuel tank vapor ignition due to lightning, rather than focus solely on the prevention of ignition sources.

Summary of the Legal Basis:

The FAA's authority to issue rules regarding aviation safety is found in title 49 of the United States Code. Subtitle I, section 106 describes the authority of the FAA Administrator. Subtitle VII, Aviation Programs, describes in more detail the scope of the agency's authority. This rulemaking is promulgated under the authority described in Subtitle VII, Part A, subpart III, section 44701, ''General requirements.'' Under that section, the FAA is charged with promoting safe flight of civil aircraft in air commerce by prescribing minimum standards required in the interest of safety for the design and performance of aircraft, regulations and minimum standards in the interest of aviation safety for inspecting, servicing, and overhauling aircraft, and regulations for other practices, methods, and procedures the Administrator finds necessary for safety in air commerce. This regulation is within the scope of that authority because it prescribes safety standards for the design of transport category airplanes and requirements necessary for safety for the design, production, operation, and maintenance of those airplanes, and for other practices, methods, and procedures related to those airplanes.

Alternatives:

The FAA's alternatives are to 1) leave the requirement as it currently exists (however this would not address the problem) or to 2) publish the rulemaking and reduce the number of applicants consistently seeking exemptions to compliance with sec. 25.981 for fuel tank structural lightning.

Anticipated Costs and Benefits:

This rule is a retrospective regulatory review rulemaking under Executive Order 13563. This rule would be relieving for both government and industries with the estimated net benefits. We assess regulatory benefits based on resources saved for reducing regulatory burden on both industry and the FAA. The total combined savings would be about $610 million or $451 million present value at a seven percent discount rate. The lower and the higher estimates of the total combined regulatory savings would be between $384 million and $836 million ($283 million and $618 million present value at a 7 percent discount rate, respectively). The proposed rule would maintain achieved safety levels related to fuel tank structure and system lightning protection commensurate with the current requirements.

Risks:

If we don't publish the rule, there is a risk of a continued paperwork burden for the public and the FAA.