System Safety Assessments

<RULE> DEPARTMENT OF TRANSPORTATION <SUBAGY>Federal Aviation Administration</SUBAGY> <CFR>14 CFR Part 25</CFR> <DEPDOC>[Docket No.: FAA-2022-1544; Amdt. No. 25-152]</DEPDOC> <RIN>RIN 2120-AJ99</RIN> <SUBJECT>System Safety Assessments</SUBJECT> <HD SOURCE="HED">AGENCY:</HD> Federal Aviation Administration (FAA), Department of Transportation (DOT). <HD SOURCE="HED">ACTION:</HD> Final rule. <SUM> <HD SOURCE="HED">SUMMARY:</HD> The FAA is amending certain airworthiness regulations to standardize the criteria for conducting safety assessments for systems, including flight controls and powerplants, installed on transport category airplanes. With this action, the FAA seeks to reduce risk associated with airplane accidents and incidents that have occurred in service, and reduce risk associated with new technology in flight control systems. The intended effect of this rulemaking is to improve aviation safety by making system safety assessment (SSA) certification requirements more comprehensive and consistent. </SUM> <EFFDATE> <HD SOURCE="HED">DATES:</HD> Effective September 26, 2024. </EFFDATE> <HD SOURCE="HED">ADDRESSES:</HD> For information on where to obtain copies of rulemaking documents and other information related to this final rule, see “How to Obtain Additional Information” in the <E T="02">SUPPLEMENTARY INFORMATION</E> section of this document. <FURINF> <HD SOURCE="HED">FOR FURTHER INFORMATION CONTACT:</HD> Todd Martin, Technical Policy Branch, Policy and Standards Division, Aircraft Certification Service, Federal Aviation Administration, 2200 South 216th Street, Des Moines, WA 98198; telephone and fax (206) 231-3210; email <E T="03">Todd.Martin@faa.gov.</E> </FURINF> <SUPLINF> <HD SOURCE="HED">SUPPLEMENTARY INFORMATION:</HD> <HD SOURCE="HD1">I. Authority for This Rulemaking</HD> The FAA's authority to issue rules on 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 FAA'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 regulations and minimum standards for the design and performance of aircraft that the Administrator finds necessary for safety in air commerce. This regulation is within the scope of that authority. It prescribes new safety standards for the design and operation of transport category airplanes. <HD SOURCE="HD1">II. Acronyms Frequently Used in This Document</HD> <GPOTABLE COLS="2" OPTS="L2,i1" CDEF="s100,r200"> <TTITLE>Table 1—Acronyms Frequently Used in This Document</TTITLE> <CHED H="1">Acronym</CHED> <CHED H="1">Definition</CHED> <ROW> <ENT I="01">AC</ENT> <ENT>Advisory Circular.</ENT> </ROW> <ROW> <ENT I="01">AD</ENT> <ENT>Airworthiness Directive.</ENT> </ROW> <ROW> <ENT I="01">AFM</ENT> <ENT>Airplane Flight Manual.</ENT> </ROW> <ROW> <ENT I="01">ALS</ENT> <ENT>Airworthiness Limitations section.</ENT> </ROW> <ROW> <ENT I="01">ARAC</ENT> <ENT>Aviation Rulemaking Advisory Committee.</ENT> </ROW> <ROW> <ENT I="01">ASAWG</ENT> <ENT>Airplane Level Safety Analysis Working Group.</ENT> </ROW> <ROW> <ENT I="01">CAST</ENT> <ENT>Commercial Aviation Safety Team.</ENT> </ROW> <ROW> <ENT I="01">CMR</ENT> <ENT>Certification Maintenance Requirement.</ENT> </ROW> <ROW> <ENT I="01">CS-25</ENT> <ENT>Certification Specifications for Large Aeroplanes (issued by EASA).</ENT> </ROW> <ROW> <ENT I="01">CSL+1</ENT> <ENT>Catastrophic Single Latent Failure Plus One (a failure condition).</ENT> </ROW> <ROW> <ENT I="01">EASA</ENT> <ENT>European Union Aviation Safety Agency.</ENT> </ROW> <ROW> <ENT I="01">ELOS</ENT> <ENT>Equivalent Level of Safety.</ENT> </ROW> <ROW> <ENT I="01">EWIS</ENT> <ENT>Electrical Wiring Interconnection System.</ENT> </ROW> <ROW> <ENT I="01">FCHWG</ENT> <ENT>Flight Controls Harmonization Working Group.</ENT> </ROW> <ROW> <ENT I="01">FTHWG</ENT> <ENT>Flight Test Harmonization Working Group.</ENT> </ROW> <ROW> <ENT I="01">ICA</ENT> <ENT>Instructions for Continued Airworthiness.</ENT> </ROW> <ROW> <ENT I="01">LDHWG</ENT> <ENT>Loads and Dynamics Harmonization Working Group.</ENT> </ROW> <ROW> <ENT I="01">NTSB</ENT> <ENT>National Transportation Safety Board.</ENT> </ROW> <ROW> <ENT I="01">PPIHWG</ENT> <ENT>Powerplant Installation Harmonization Working Group.</ENT> </ROW> <ROW> <ENT I="01">SDAHWG</ENT> <ENT>System Design and Analysis Harmonization Working Group.</ENT> </ROW> <ROW> <ENT I="01">SLF</ENT> <ENT>Significant Latent Failure.</ENT> </ROW> <ROW> <ENT I="01">SSA</ENT> <ENT>System Safety Assessment.</ENT> </ROW> </GPOTABLE> <HD SOURCE="HD1">Table of Contents</HD> <EXTRACT> <FP SOURCE="FP-2">I. Authority for This Rulemaking</FP> <FP SOURCE="FP-2">II. Acronyms Frequently Used in This Document</FP> <FP SOURCE="FP-2">III. Overview of Final Rule</FP> <FP SOURCE="FP-2">IV. Background</FP> <FP SOURCE="FP1-2">A. Statement of the Problem</FP> <FP SOURCE="FP1-2">B. Related Actions</FP> <FP SOURCE="FP1-2">C. NTSB Recommendations</FP> <FP SOURCE="FP1-2">D. Summary of the NPRM</FP> <FP SOURCE="FP1-2">E. General Overview of Comments</FP> <FP SOURCE="FP-2">V. Discussion of Comments and the Final Rule</FP> <FP SOURCE="FP1-2">A. Section 25.4, Definitions</FP> <FP SOURCE="FP1-2">B. Section 25.302, Interaction of Systems and Structures</FP> <FP SOURCE="FP1-2">C. Section 25.629, Aeroelastic Stability Requirements</FP> <FP SOURCE="FP1-2">D. Section 25.671, Flight Control Systems</FP> <FP SOURCE="FP1-2">E. Section 25.901, Engine Installation</FP> <FP SOURCE="FP1-2">F. Section 25.933, Reversing Systems</FP> <FP SOURCE="FP1-2">G. Section 25.1301, Function and Installation</FP> <FP SOURCE="FP1-2">H. Section 25.1309, Equipment, Systems and Installations</FP> <FP SOURCE="FP1-2">I. Section 25.1365, Electrical Appliances, Motors, and Transformers</FP> <FP SOURCE="FP1-2">J. Miscellaneous Comments</FP> <FP SOURCE="FP1-2">K. Advisory Material</FP> <FP SOURCE="FP-2">VI. Regulatory Notices and Analyses</FP> <FP SOURCE="FP1-2">A. Regulatory Evaluation</FP> <FP SOURCE="FP1-2">B. Regulatory Flexibility Determination</FP> <FP SOURCE="FP1-2">C. International Trade Impact Assessment</FP> <FP SOURCE="FP1-2">D. Unfunded Mandates Assessment</FP> <FP SOURCE="FP1-2">E. Paperwork Reduction Act</FP> <FP SOURCE="FP1-2">F. International Compatibility</FP> <FP SOURCE="FP1-2">G. Environmental Analysis</FP> <FP SOURCE="FP-2">VII. Executive Order Determinations</FP> <FP SOURCE="FP1-2">A. Executive Order 13132, Federalism</FP> <FP SOURCE="FP1-2">B. Executive Order 13175, Consultation and Coordination With Indian Tribal Governments</FP> <FP SOURCE="FP1-2">C. Executive Order 13211, Regulations That Significantly Affect Energy Supply, Distribution, or Use</FP> <FP SOURCE="FP1-2">D. Executive Order 13609, Promoting International Regulatory Cooperation</FP> <FP SOURCE="FP-2">VIII. Additional Information</FP> <FP SOURCE="FP1-2"> A. Electronic Access and Filing </FP> <FP SOURCE="FP1-2">B. Small Business Regulatory Enforcement Fairness Act</FP> </EXTRACT> <HD SOURCE="HD1">III. Overview of Final Rule</HD> The FAA is amending regulations in title 14, Code of Federal Regulations (14 CFR) part 25 (Airworthiness Standards: Transport Category Airplanes) related to the safety assessment  <SU>1</SU> <FTREF/> of airplane systems. The changes to part 25 affect applicants for type certification and operators of transport category airplanes. Applicants for type certification will be required to conduct their SSAs in accordance with the revised regulations. Changes to the Instructions for Continued Airworthiness (ICA) affect operators of newly certified airplanes, although the impact on those operators is not significant. <FTNT> <SU>1</SU>  A system safety assessment is a structured process intended to systematically identify the risks pertinent to the design of aircraft systems, and to show that the systems meet safety requirements. </FTNT> The FAA is revising and adding new safety standards to reduce the likelihood of potentially catastrophic risks due to latent failures in critical systems. Because modern aircraft systems (for example, avionics and fly-by-wire systems) are much more integrated than they were when the current safety criteria in § 25.1309 and other system safety assessment rules were established in 1970, <SU>2</SU> <FTREF/> the new standards are more consistent for all systems of the airplane, reducing the chance of a hazard falling into a gap between the different regulatory requirements for different systems. <FTNT> <SU>2</SU>  35 FR 5665 (Apr. 8, 1970). </FTNT> Consistent criteria for conducting SSAs also provides predictability for applicants by reducing the number of issue papers and special conditions necessary for airplane certification projects. <SU>3</SU> <FTREF/> <FTNT> <SU>3</SU>  As discussed in the preamble, special conditions are rules of particular applicability that the FAA issues to address novel or unusual design features. See 14 CFR 21.16. </FTNT> Specifically, this final rule— • Requires that applicants limit the likelihood of a catastrophic failure condition that results from a combination of two failures, either of which could be latent for more than one flight. See § 25.1309(b)(5). • Revises safety assessment regulations to eliminate ambiguity in, and provide consistency between, the safety assessments that applicants must conduct for different types of airplane systems. Section 25.1309 continues to contain the safety assessment criteria applicable to most airplane systems. Section 25.901(c) (power ━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━ Preview showing 10k of 211k characters. Full document text is stored and available for version comparison. ━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━