[Federal Register Volume 77, Number 183 (Thursday, September 20, 2012)]
[Rules and Regulations]
[Page 58301]
From the Federal Register Online via the Government Publishing Office [www.gpo.gov]
[FR Doc No: 2012-23105]

Rules and Regulations
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Federal Register / Vol. 77, No. 183 / Thursday, September 20, 2012 / 
Rules and Regulations

[[Page 58301]]


Federal Aviation Administration

14 CFR Part 33

[Docket No. FAA-2012-0941; Amendment No. 33-33]
RIN 2120-AF57

Technical Amendment; Airworthiness Standards: Aircraft Engines; 

AGENCY: Federal Aviation Administration (FAA), DOT.

ACTION: Technical amendment; correction.


SUMMARY: The FAA is correcting a technical amendment published on July 
5, 2012 (77 FR 39623). In that technical amendment, the FAA clarified 
aircraft engine vibration test requirements in the airworthiness 
standards. The technical amendment was in response to inquiries from 
applicants requesting FAA engine type certifications and aftermarket 
certifications, such as supplemental type certificates, parts 
manufacturing approvals, and repairs. We revised the regulation to 
clarify that engine surveys require an engine test. Representatives of 
industry suggested that our technical amendment was in fact, a 
substantive change in the regulation, not a clarification. The FAA is 
correcting our prior action in response to that industry claim. This 
document amends the FAA's regulations to reverse the changes to Sec.  
33.83(a) amendment 33-33 and restore Sec.  33.83(a) to its previous 
amendment 33-17.

DATES: This corrective action becomes effective September 20, 2012.

FOR FURTHER INFORMATION CONTACT: For technical questions concerning 
this action, contact Dorina Mihail, Federal Aviation Administration, 
Engine and Propeller Directorate, Standards Staff, ANE-110, 12 New 
England Executive Park, Burlington, Massachusetts 01803-5229; (781) 
238-7153; facsimile: (781) 238-7199; email: [email protected].
    For legal questions concerning this action, contact Vincent 
Bennett, Federal Aviation Administration, Office of Regional Counsel, 
ANE-7, 12 New England Executive Park, Burlington, Massachusetts 01803-
5299; telephone (781) 238-7044; fax (781) 238-7055; email 
[email protected].



    On July 5, 2012, the FAA published a Technical Amendment entitled, 
``Airworthiness Standards: Aircraft Engine'' (77 FR 39623). In that 
technical amendment, the FAA intended to clarify vibration test 
requirements in Sec.  33.83 of 14 Code of Federal Regulations Part 33. 
By letter dated August 3, 2012, the Modification and Replacement Parts 
Association (MARPA) asserts that the rule appears to be a substantive 
change that should have been open to public comment. The MARPA further 
asserts that had the rule been open for comment, it and others would 
have commented that the technical amendment undermines the existing 
regulatory system, rather than improving it, and that it imposes 
unnecessary burdens on the applicant and the government with no 
commensurate safety benefit. We do not agree with MARPA's assertion 
that the rule change was substantive. However, in the interest of 
transparency in the rulemaking process, we are changing the language of 
Sec.  33.83(a) amendment 33-33 back to the language in Sec.  33.83(a) 
of the previous amendment 33-17.

List of Subjects in 14 CFR Part 33

    Aircraft, Aviation safety.

The Correcting Amendment

    In consideration of the following, the Federal Aviation 
Administration corrects part 33 of Title 14, Code of Federal 
Regulations as follows:


1. The authority citation for part 33 continues to read as follows:

    Authority: 49 U.S.C. 106(g), 40113, 44701-44702, 44704.

2. Revise Sec.  33.83(a) to read as follows:

Sec.  33.83  Vibration test.

    (a) Each engine must undergo vibration surveys to establish that 
the vibration characteristics of those components that may be subject 
to mechanically or aerodynamically induced vibratory excitations are 
acceptable throughout the declared flight envelope. The engine surveys 
shall be based upon an appropriate combination of experience, analysis, 
and component test and shall address, as a minimum, blades, vanes, 
rotor discs, spacers, and rotor shafts.
* * * * *

    Issued in Washington, DC, on September 13, 2012.
Lirio Liu,
Acting Director, Office of Rulemaking.
[FR Doc. 2012-23105 Filed 9-19-12; 8:45 am]