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Regulatory Brief -- FAA issues tougher standards for GA alterationsRegulatory Brief -- FAA issues tougher standards for GA alterations

Regulatory Brief

FAA issues tougher standards for GA alterations

The issue:

On June 7, 2000, the FAA issued the "Type Certification Procedures for Changed Products" (aka the Changed Products Rule) final rule. The Changed Product Rule (CPR) amends those parts of regulations 14 CFR �11, 21, 25 that address the way in which aircraft modifications requiring a Supplemental Type Certificate (STC) receive FAA certification. The "Changed Products Rule" (CPR) requires that any "significant" modifications to an aircraft requiring a Supplemental Type Certificate (STC) and all systems affected by that STC modification must meet the latest amendment to the certification standards, regardless of the earlier certification regulation that was used to certify the aircraft being modified ("original certification basis").

As a required part of the CPR implementation plan, an Advisory Circular (AC) 21.101 was issued August 3, 2001 that addressed large aircraft but did not address the needs of typical small General Aviation aircraft. A draft revision of AC 21.101 was published April 23, 2002 to address small aircraft needs.

The importance to our members:

AOPA strongly believes that CPR has the potential to stifle the necessary development of safety and/or operational enhancing STC modifications. There is no doubt that there will be substantially increased costs to the STC manufacturer in order to develop additional engineering and research data necessary to meet the requirements of CPR. Many STC'd modification developers and manufacturers may simply elect not to pursue an STC, thus denying many aircraft owners an opportunity to upgrade. At the very least, the additional costs of STC development will be passed on to consumers. As a result of CPR, many potential safety or operational enhancing aircraft modifications may never come to the average GA market and many other STC'd modifications will simply be too costly for the average GA aircraft owner.

In addition, an Advisory Circular guidance addressing the "small aircraft" section of CPR is necessary so that applicants and the FAA may begin to understand the application CPR to small aircraft.

Significant provisions:

  • The original compliance dates for CPR were December 9, 2001 for all aircraft over 6,000 pounds maximum certificated gross weight and December 10, 2002 for all other aircraft and non-turbine rotorcraft 3,000 pounds or less.
  • As a result of the complexities surrounding CPR implementation including the issuance of a truly viable Advisory Circular (AC), the FAA changed CPR compliance dates to June 10, 2003 for all aircraft.
  • Before CPR, all modifications involving a STC, including those that enhance an aircraft's operational capabilities or safety, only had to be certified to the original certification basis (earlier rules) of the aircraft being modified. Though many manufacturers of STC'd modifications attempted to meet a later certification regulation amendment, often they elected to meet aircraft's original certification basis. This pre-CPR method of certification allowed for flexibility of design with optimal research and development costs without compromising the current level safety of the aircraft being changed. CPR dramatically changed this STC certification method.
  • After CPR, with the exception of "smaller aircraft" 6,000 lbs and under, all STC'd modifications must meet a later, or the latest, amendment to the certification regulations unless the applicant convinces the FAA that the proposed modification is not "significant" or can prove that compliance with a later amendment is "impractical" (the terms "significant" and "impractical" are specific terms used in the CPR language).
  • Regulatory compliance with CPR relies on several key terms (such as "significant" and "impractical") that the FAA fails to adequately define in the final rule language.
    • Compliance with CPR also relies heavily on a AC 21.101 that is currently under-going a much needed revision using the input from AOPA and other industry organizations.
    • Specialized appendices to AC 21.101 developed with the help of AOPA are specifically intended to assist the FAA and STC'd modification manufacturers determine the relevant "significance" of small aircraft, engine, and avionics changes and help determine which regulation amendment applies.
  • The "Smaller Aircraft" exception of CPR also places the regulatory burden on the FAA to analyze which amendment to the regulations the aircraft STC modification must meet, starting with the aircraft's earlier original certification basis.
  • While assisting the FAA in the development of the Advisory Circular, AOPA learned that the FAA wanted to ignore some of its regulatory responsibility under the "Small Aircraft" exception to CPR -
    • The FAA stated during a meeting that it does not wish to adhere to the new regulation's small aircraft exception by conducting the intended "earlier to later" regulatory applicability analysis. Instead of using the method stated in the final rule (using the earlier original certification basis of the aircraft being changed and determining whether or not a later certification standard is applicable or appropriate,) the FAA wanted to start with the latest amendment level first and then attempt to justify an earlier amendment level to the aircraft certification regulations.
    • AOPA argued that the " earlier to later" amendment approach per the "Smaller Aircraft' exception to CPR places considerably less burden on the applicant than the "latest to earlier" approach that the FAA must use for larger aircraft. By using the "earlier to later" amendment approach, the applicant is much less likely to be required to make a prohibitively expensive case for an earlier amendment level for modification approval. The "Smaller Aircraft" exception wording in CPR was specifically and intentionally designed to treat changes to "Smaller Aircraft" differently for that very reason.
  • The original AC 21.101-1 did not provide the proper guidance for the application of CPR with respect to "smaller aircraft".
  • After the first version the AC was published, AOPA immediately lobbied the FAA to incorporate the proper and necessary guidance concerning the "smaller aircraft" exception to CPR. The FAA management finally agreed with AOPA back in late August 2001 and has published a draft revision.
  • The FAA invites public comment to the draft revision to AC 21.101 published in the Federal Register on April 23, 2002. The formal comment period closes on May 25, 2002.

AOPA position:

AOPA strongly feels that CPR was not necessary, especially for GA. AOPA believes that requiring an aircraft modification to meet the latest amendment to the certification regulations instead of the earlier original certification basis of the aircraft being changed does not necessarily mean that a more safe condition will prevail. In fact, the overall safety record of the GA fleet indicates that the previous method of certifying modifications requiring a Supplemental Type Certificate (STC) has continually resulted in GA safety improvements. There is no specific safety data or safety study presented by the FAA that supports its safety reason for promulgating the "Changed Product Rule" (CPR) or to include GA. In addition, the economic burden placed upon small businesses (who produce a majority of GA aircraft STCs) and the majority of small aircraft owners (which comprises the majority of the entire U.S. aviation fleet) will only serve to considerably stifle and suppress the cause of safety.

AOPA actively lobbied the FAA to live up to its regulatory responsibilities under the "Smaller Aircraft" exception of CPR and that it adopt the agreed to recommended changes and additions to AC 21.101. As a result, the FAA has published a draft revision to the AC and AOPA agrees with the changes as they pertain to small aircraft.


  • April 23, 2002, draft changes to Advisory Circular 21.101 are published for public comment.
  • August 3, 2001, Advisory Circular 21.101 is published.
  • May 30, 2001, FAA publishes its disposition of public comments to CPR final rule.
  • October 2000, AOPA becomes a member of the AC 21.101 Development Small Aircraft Work Group in an effort to help mitigate the effects of CPR on GA.
  • August 7, 2000 AOPA again sends additional comments to the FAA in opposition to CPR.
  • June 7, 2000 FAA publishes CPR as a final rule with a request for public comments.
  • In 1998 AOPA sends comments to the FAA opposing CPR and requesting relief for GA aircraft.
  • In 1998 FAA issues the "Changed Product Rule" (CPR) Notice of Proposed Rulemaking with a request for public comments.

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