42020 Federal Register / Vol. 76, No. 137 / Monday, July 18, 2011 / Rules and Regulations 

respondents, and the correspondent 

shall pass back to its respondents 

interest paid on balances in the 

correspondent’s account. 

* * * * * 

PART 217—PROHIBITION AGAINST 

PAYMENT OF INTEREST ON DEMAND 

DEPOSITS (REGULATION Q)— 

[REMOVED AND RESERVED] 

■ 3. Part 217 is removed and reserved. 

PART 230—TRUTH IN SAVINGS 

(REGULATION DD) 

■ 4. The authority citation for part 230 

continues to read as follows: 

Authority: 12 U.S.C. 4301 et seq. 

Supplement I to Part 230—Official Staff 

Interpretations 

■ 5. In Supplement I to Part 230: 

■ A. Under Section 230.2—Definitions, 

paragraph (n) Interest, is revised. 

■ B. Under Section 230.7—Payment of 

interest, subsection (a)(1) Permissible 

methods, the introductory text of 

paragraph (5) is revised. 

The revisions read as follows: 

Supplement I to Part 230—Official Staff 

Interpretations 

* * * * * 

Section 230.2 Definitions. 

* * * * * 

(n) Interest 

1. Relation to bonuses. Bonuses are not 

interest for purposes of this regulation. 

* * * * * 

Section 230.7 Payment of interest. 

(a)(1) Permissible methods 

* * * * * 

5. Maturity of time accounts. Institutions 

are not required to pay interest after time 

accounts mature. Examples include: 

* * * * * 

By order of the Board of Governors of the 

Federal Reserve System, July 12, 2011. 

Jennifer J. Johnson, 

Secretary of the Board. 

[FR Doc. 2011–17886 Filed 7–15–11; 8:45 am] 

BILLING CODE 6210–01–P 

DEPARTMENT OF TRANSPORTATION 

Federal Aviation Administration 

14 CFR Part 33 

[Docket No. FAA–2010–0398; Amendment 

No. 33–31] 

RIN 2120–AJ62 

Airworthiness Standards; Rotor 

Overspeed Requirements 

AGENCY: Federal Aviation 

Administration (FAA), DOT. 

ACTION: Final rule. 

SUMMARY: This rule will amend the 

aircraft turbine engine rotor overspeed 

type certification standards. This action 

establishes uniform rotor overspeed 

design and test requirements for aircraft 

engines and turbochargers certificated 

by the FAA and the European Aviation 

Safety Agency (EASA). The rule also 

establishes uniform standards for the 

design and testing of engine rotor parts 

in the United States and in Europe, 

eliminating the need to comply with 

two differing sets of requirements. 

DATES: This amendment becomes 

effective September 16, 2011. 

FOR FURTHER INFORMATION CONTACT: For 

technical questions concerning this final 

rule, contact Tim Mouzakis, Engine and 

Propeller Directorate Standards Staff, 

ANE–111, Engine and Propeller 

Directorate, Federal Aviation 

Administration, 12 New England 

Executive Park, Burlington, 

Massachusetts 01803–5299; telephone 

(781) 238–7114; fax (781) 238–7199; email timoleon.mouzakis@.faa.gov. For 

legal questions concerning this final 

rule contact Vincent Bennett, ANE–7, 

Office of Regional Counsel, Federal 

Aviation Administration, 12 New 

England Executive Park, Burlington, 

Massachusetts 01803–5299; telephone 

(781) 238–7044; fax (781) 238–7055; email vincent.bennett@faa.gov. 

SUPPLEMENTARY INFORMATION: 

Authority for This Rulemaking 

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. 

We are issuing this rulemaking 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 

for practices, methods, and procedures 

the Administrator finds necessary for 

safety in air commerce, including 

minimum safety standards for aircraft 

engines. This final rule is within the 

scope of that authority because it 

updates existing regulations for rotor 

overspeed for aircraft turbine engines. 

Background 

Part 33 of Title 14, Code of Federal 

Regulations, prescribes airworthiness 

standards for original and amended type 

certificates for aircraft engines. The 

European Aviation Safety Agency 

(EASA) Certification Specification— 

Engines (CS–E) prescribes 

corresponding airworthiness standards 

to certify aircraft engines in Europe. 

While part 33 and the CS–E are similar, 

they differ in several respects. These 

differences may result in added costs, 

delays, and time required for 

certification. This rule will harmonize 

applicable U.S. and EASA standards 

and clarify existing overspeed 

requirements for aircraft turbine engine 

rotor parts. 

Summary of the NPRM 

The FAA published a notice of 

proposed rulemaking (NPRM) on April 

26, 2010 (75 FR 21523). The proposed 

changes establish a uniform certification 

basis for aircraft turbine engine rotor 

parts between the FAA and EASA. The 

proposal discussed requiring that rotor 

parts be designed with a safety margin 

large enough that the parts have an 

overspeed capability that exceeds the 

engine’s certified operating conditions, 

including overspeed conditions which 

can occur in the event of a failure of 

another engine component and/or 

system malfunction. For failures that 

may result in an overspeed, the proposal 

limited rotor growth to that which 

would not lead to a hazardous condition 

as defined in § 33.75. The comment 

period for the NPRM closed on July 26, 

2010. 

Summary of the Final Rule 

There are minor differences between 

the proposal and this final rule. Sections 

33.27(c) and (g) were changed in 

response to comments and our review of 

the proposal. This rule harmonizes rotor 

overspeed requirements found in part 

33 with EASA CS–E 840, Rotor 

Integrity. 

Summary of Comments 

The FAA received comments from 

Rolls-Royce, General Electric Aviation, 

Turbomeca, Pratt and Whitney, and 

General Aviation Manufacturers 

Association (GAMA). The commenters 

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Federal Register / Vol. 76, No. 137 / Monday, July 18, 2011 / Rules and Regulations 42021 

suggested minor improvements in the 

following areas: 

• Differences in the definition of 

‘‘extremely remote’’ in § 33.27(c); 

• Exclusions of shaft sections from 

overspeed tests; 

• Material properties of test rotors; 

and 

• Validation of analytical tools. 

Discussion of the Final Rule 

The final rule requires that rotor parts 

be designed with a safety margin large 

enough that the parts have an overspeed 

capability exceeding the engine’s 

certified operating conditions, including 

overspeed conditions, which can occur 

in the event of a failure of another 

engine component and/or system 

malfunction. For failures that may result 

in an overspeed, the final rule limits 

rotor growth to that which would not 

lead to a hazardous condition as defined 

by § 33.75. 

To harmonize FAA and EASA 

standards, the FAA will: 

• Change the current FAA overspeed 

design margin from 115 to 120 percent 

of maximum permissible speed for all 

engine ratings except one engine 

inoperative (OEI) ratings of less than 21⁄2

minutes; 

• Change the current FAA overspeed 

design margin from 100 to 105 percent 

for operating conditions associated with 

multiple failures; 

• Introduce similar OEI overspeed 

design requirements; 

• Require new similar rotor pass/fail 

design criteria; 

• Require similar overspeed margin 

requirements; 

• Allow the use of validated 

structural analysis tools to demonstrate 

compliance; 

• Require that validated structural 

analysis tools be calibrated to actual 

overspeed tests of similar rotors; and 

• Allow engine test durations of less 

than 5 minutes for failure conditions for 

which a 5-minute duration is not 

realistic. 

Like EASA’s CS–E, the final rule 

specifies that rotors may not burst for 

overspeed conditions that do not 

involve component or system failure. 

For component or engine failures that 

result in an overspeed, the final rule 

specifies that rotors may not burst and 

limits the amount of rotor growth. 

Differences in Definition of Probability 

of Occurrence in § 33.27(c) 

Section 33.27(c) proposed that 

overspeeds resulting from combinations 

of failures must also be considered 

unless the applicant can show that the 

probability of occurrence is not greater 

than 10¥9 per flight. Rolls-Royce, 

General Electric, Turbomeca, Pratt and 

Whitney, and GAMA commented that 

the proposed criteria in § 33.27(c) is 

inconsistent with § 33.75, CS–E 510, 

and CS–E 840. The commenters also 

took issue with the FAA’s criteria of 

probability of occurrence as not greater 

than 10¥9 and FAA’s use of the term 

‘‘per flight.’’ They suggested that the 

probability of occurrence should follow 

the more flexible criteria of not greater 

that ‘‘extremely remote,’’ which has 

been defined in the previous 

rulemakings as between 10¥7 to 10¥9. 

Finally, the commenters indicated that 

the term ‘‘per engine flight hour’’ should 

be substituted for ‘‘per flight’’ to be 

consistent with § 33.75 and CS–E 840. 

We agree with the revised criteria 

proposed by the commenters. The final 

rule will reflect that overspeeds 

resulting from combinations of failures 

must also be considered, unless the 

applicant can show that the probability 

of occurrence is not greater than 

extremely remote (probability range of 

10¥7 to 10¥9 per engine flight hour). 

Exclusion of Shaft Sections From 

Overspeed Tests 

Proposed § 33.27(f) allows exclusion 

of certain shaft sections, but not the 

whole shaft system, from the 

requirement when determining the 

terminal rotor speed due to shaft failure. 

Rolls-Royce commented that § 33.27(c) 

allows exclusion on a probability basis 

only of overspeeds ‘‘resulting from 

combinations of failures,’’ whereas CS– 

E 840(c) allows the probability 

exclusion for any cause if ‘‘it can be 

shown to be Extremely Remote under 

the provisions of CS–E 850.’’ 

Rolls-Royce requested that the lead 

sentence of § 33.27(c) be changed to, 

‘‘The highest overspeed which will 

result from a complete loss of load on 

a turbine rotor, unless it can be shown 

to be Extremely Remote or except as 

provided by paragraph (f) of this 

section.* * *’’. The change proposed by 

Rolls-Royce would allow exclusion of 

the whole shaft system from 

consideration of failure, which is not 

the intent of the rule. Our changes to 

overspeed requirements due to shaft 

failures are consistent with those in CS– 

E–840 and CS–E–850(b). We did not 

change the rule due to this comment. 

Material Properties of Test Rotors 

Section 33.27(a)(1) proposed that test 

rotors used to demonstrate compliance 

with this section that do not have the 

most adverse combination of material 

properties and dimensional tolerances 

must be tested at conditions which have 

been adjusted to ensure the minimum 

specification rotor possesses the 

required overspeed capability. 

Rolls-Royce claimed that determining 

the precise ‘‘most adverse combination’’ 

is not practical. Rolls-Royce noted that 

Advisory Circular (AC) 33.27–1, 

paragraph 7.g indicates that the 

applicant should consider ‘‘the most 

adverse combination of dimensional 

tolerances and material properties,’’ 

which allows the use of engineering 

judgment and best practices in lieu of an 

exhaustive assessment of all possible 

combinations and permutations. As a 

result, Rolls-Royce requested that the 

phrase ‘‘that do not have the most 

adverse combination of material 

properties and dimensional tolerances’’ 

be omitted from § 33.27(a)(1). 

We disagree. We find that our 

proposed wording of § 33.27(a)(1) is 

consistent with EASA’s regulation CS– 

E 840(a) and that the suggested change 

would not meet the intent of the 

proposed paragraph. Our intent in 

§ 33.27(a)(1) is to ensure that the 

minimum specifications rotor is capable 

of meeting the test requirements of the 

proposed rule. Industry has been 

complying with this requirement, as 

stated in EASA regulations, for several 

years. The change proposed by RollsRoyce would, therefore, diverge from 

EASA’s rule and could increase cost to 

manufacturers. We did not change the 

final rule due to this comment. 

Validation of Analytical Tools 

We proposed in § 33.27(g) that if 

analysis is used to meet the overspeed 

requirements, then the analytical tool 

must be calibrated to prior overspeed 

test results of a similar rotor. The tool 

must be calibrated for the same material, 

rotor geometry, stress level, and 

temperature range as the rotor being 

certified. Calibration includes the ability 

to accurately predict rotor dimensional 

growth and burst speed. The predictions 

must also show that the rotor being 

certified does not have lower burst and 

growth margins than rotors used to 

calibrate the tool. 

Rolls-Royce commented that the 

requirements for validation of analytical 

tools eligible for use in showing 

compliance in lieu of testing are overly 

restrictive. Rolls-Royce said the 

language of § 33.27(g) appears to 

invalidate any potential for the 

applicant to propose analysis methods 

to the Administrator for acceptance per 

AC 33.27–1, paragraphs 7.b and 7.c. 

Rolls-Royce noted that it seems unlikely 

that an applicant will have a tool 

calibrated for the same conditions and 

the same rotor as that being certified; 

such a certification appears redundant. 

Rolls-Royce requested that § 33.27(g) be 

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42022 Federal Register / Vol. 76, No. 137 / Monday, July 18, 2011 / Rules and Regulations 

modified to read: ‘‘If analysis is used to 

meet the overspeed requirements, then 

the analytical tool must be calibrated to 

prior overspeed test results of a similar 

rotor.’’ 

We agree that the language of 

proposed 33.27(g) appears overly 

restrictive. We changed the language to 

read the analytical tool must be 

‘‘validated’’ instead of ‘‘calibrated’’ for 

each material. The analytical model 

must be validated using rotors which 

‘‘surround’’ the rotor being certified in 

terms of ‘‘shape, stresses and 

temperature.’’ The final rule now reads: 

‘‘If analysis is used to meet the 

overspeed requirements, then the 

analytical tool must be validated to 

prior overspeed test results of a similar 

rotor. The tool must be validated for 

each material. The rotor being certified 

must not exceed the boundaries of the 

rotors being used to validate the 

analytical tool in terms of geometric 

shape, operating stress, and 

temperature.’’ This changed wording is 

also consistent with EASA advisory 

material AMC E 840. 

Definition of Terms Used in the Final 

Rule 

The following definitions of terms 

used in the final rule are provided for 

clarity: 

Maximum permissible rotor speed. 

The maximum approved rotor speed, 

including transients, for the maximum 

approved rating, including One-EngineInoperative (OEI) ratings. 

Overspeed Capability. The r.p.m. 

(revolutions per minute) at which the 

part fails or bursts. 

Rotor Growth. The total increase in a 

rotor part’s radial dimensions caused by 

an overspeed condition. Total growth 

includes both the recoverable (elastic) 

and the permanent (plastic) change in 

rotor dimensions. 

Rulemaking Analyses and Notices 

Paperwork Reduction Act 

The Paperwork Reduction Act of 1995 

(44 U.S.C. 3507(d)) requires that the 

FAA consider the impact of paperwork 

and other information collection 

burdens imposed on the public. We 

have determined there is no new 

requirement for information collection 

associated with this final rule. 

International Compatibility 

In keeping with U.S. obligations 

under the Convention on International 

Civil Aviation, it is FAA policy to 

comply with International Civil 

Aviation Organization (ICAO) Standards 

and Recommended Practices, to the 

maximum extent practicable. We 

determined that no ICAO Standards or 

Recommended Practices corresponding 

to these proposed regulations exist. 

Regulatory Evaluation, Regulatory 

Flexibility Determination, International 

Trade Impact Assessment, and 

Unfunded Mandates Assessment 

Proposed changes to Federal 

regulations must undergo several 

economic analyses. First, Executive 

Order 12866 and Executive Order 13563 

direct that each Federal agency propose 

or adopt a regulation only upon a 

reasoned determination that the benefits 

of the intended regulation justify its 

costs. Second, the Regulatory Flexibility 

Act of 1980 (Pub. L. 96–354) requires 

agencies to analyze the economic 

impact of regulatory changes on small 

entities. Third, the Trade Agreements 

Act (Pub. L. 96–39) prohibits agencies 

from setting standards that create 

unnecessary obstacles to the foreign 

commerce of the United States. In 

developing U.S. standards, this Trade 

Act requires agencies to consider 

international standards and, where 

appropriate, that they be the basis of 

U.S. standards. Fourth, the Unfunded 

Mandates Reform Act of 1995 

(Pub. L. 104–4) requires agencies to 

prepare a written assessment of the 

costs, benefits, and other effects of 

proposed or final rules that include a 

Federal mandate likely to result in the 

expenditure by State, local, or tribal 

governments, in the aggregate, or by 

private sector, of $100 million or more 

annually (adjusted for inflation with 

base year of 1995). This portion of the 

preamble contains the FAA’s analysis of 

the economic impacts of this final rule. 

In conducting these analyses, the FAA 

has determined that this rule: (1) Has 

benefits that justify its costs; (2) is not 

an economically ‘‘significant regulatory 

action’’ as defined in section 3(f) of 

Executive Order 12866; (3) is not 

‘‘significant’’ as defined in DOT’s 

Regulatory Policies and Procedures; (4) 

will not have a significant economic 

impact on a substantial number of small 

entities; (5) will not create unnecessary 

obstacles to the foreign commerce of the 

United States; and (6) will not impose 

an unfunded mandate on state, local, or 

tribal governments, or on the private 

sector by exceeding the threshold 

identified above. 

Total Estimated Benefits and Costs of 

This Proposed Rule 

Presently, turbine aircraft engine 

manufacturers must satisfy both FAA 

part 33 and EASA CS–E regulations to 

certify their products in the United 

States and Europe. Certification to one 

standard will improve certification 

efficiency by eliminating duplicate 

testing and documentation. We have not 

attempted to quantify the cost savings 

that may accrue due to this improved 

certification efficiency beyond noting 

that these are expected to be minor. We 

have drawn that conclusion based on 

the consensus among potentially 

affected aircraft engine manufacturers. 

Industry must currently certificate to 

the two standards that are substantively 

similar, but have a few slightly different 

testing and documentation procedures 

and requirements. The rule harmonizes 

these procedures and requirements to 

the higher standard and, thereby, may 

increase safety. In addition, by reducing 

the amount of duplicative testing that 

would need to be either witnessed or 

analyzed by the FAA, the FAA is better 

able to prioritize its resources to other, 

more safety critical areas. Consequently, 

we determined that unquantifiable 

future minimal benefits from the rule 

may also accrue. We disagreed with a 

comment determining the precise ‘‘most 

adverse combination’’ of material 

properties and dimensional tolerances 

to establish the required overspeed 

capability. However, as noted in our 

response, the commenter’s suggestion 

would result in a rule that is not 

consistent with the EASA regulations 

and the suggestion might increase costs 

to manufacturers. As a result, the FAA 

concludes that the combination of cost 

savings and potential increased safety 

benefits will make this rule cost 

beneficial. Further, we therefore 

determined that this rule is not a 

‘‘significant regulatory action’’ as 

defined in section 3(f) of Executive 

Order 12866, and is not ‘‘significant’’ as 

defined in DOT’s Regulatory Policies 

and Procedures. 

Regulatory Flexibility Determination 

The Regulatory Flexibility Act of 1980 

(Pub. L. 96–354) (RFA) establishes ‘‘as a 

principle of regulatory issuance that 

agencies shall endeavor, consistent with 

the objectives of the rule and of 

applicable statutes, to fit regulatory and 

informational requirements to the scale 

of the businesses, organizations, and 

governmental jurisdictions subject to 

regulation. To achieve this principle, 

agencies are required to solicit and 

consider flexible regulatory proposals 

and to explain the rationale for their 

actions to assure that such proposals are 

given serious consideration.’’ The RFA 

covers a wide-range of small entities, 

including small businesses, not-forprofit organizations, and small 

governmental jurisdictions. 

Agencies must perform a review to 

determine whether a rule will have a 

significant economic impact on a 

substantial number of small entities. If 

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Federal Register / Vol. 76, No. 137 / Monday, July 18, 2011 / Rules and Regulations 42023 

the agency determines that it will, the 

agency must prepare a regulatory 

flexibility analysis as described in the 

RFA. 

However, if an agency determines that 

a rule is not expected to have a 

significant economic impact on a 

substantial number of small entities, 

section 605(b) of the RFA provides that 

the head of the agency may so certify 

and a regulatory flexibility analysis is 

not required. The certification must 

include a statement providing the 

factual basis for this determination, and 

the reasoning should be clear. 

The net effect of this rule is to provide 

regulatory cost relief. Further, all but 

one U.S. aircraft turbine engine 

manufacturer exceeds the Small 

Business Administration small-entity 

criteria for aircraft engine manufacturers 

of 1,500 employees. U.S. transport 

category aircraft engine manufacturers 

include: General Electric (GE); CFM 

International (a joint company of GE 

and Snecma); Pratt & Whitney (P&W); 

Honeywell; Rolls-Royce Corporation 

(formerly Allison Engines); International 

Aero Engines (a privately-held 

consortium that includes P&W, RollsRoyce, Japanese Aero Engines 

Corporation, and MTU Aero Engines); 

and Williams International. Williams 

International is the only one of these 

manufacturers that is categorized as a 

U.S. small business by the SBA criteria. 

As this final rule reduces costs and 

there is only one small entity 

manufacturing part 33 aircraft engines, 

therefore, as FAA Administrator, I 

certify this rule will not have a 

significant economic impact on a 

substantial number of small entities. 

International Trade Impact Assessment 

The Trade Agreements Act of 1979 

(Pub. L. 96–39), as amended by the 

Uruguay Round Agreements Act 

(Pub. L. 103–465), prohibits Federal 

agencies from establishing standards or 

engaging in related activities that create 

unnecessary obstacles to the foreign 

commerce of the United States. 

Pursuant to these Acts, the 

establishment of standards is not 

considered an unnecessary obstacle to 

the foreign commerce of the United 

States, so long as the standard has a 

legitimate domestic objective, such as 

protection of safety, and does not 

operate in a manner that excludes 

imports that meet this objective. The 

statute also requires consideration of 

international standards and, where 

appropriate, that they be the basis for 

U.S. standards. We assessed the 

potential effect of this rule and 

determined that it uses European 

standards as the basis for regulation, 

and thus is consistent with the Trade 

Assessments Act. 

Unfunded Mandates Assessment 

Title II of the Unfunded Mandates 

Reform Act of 1995 (Pub. L. 104–4) 

requires each Federal agency to prepare 

a written statement assessing the effects 

of any Federal mandate in a proposed or 

final agency rule that may result in an 

expenditure of $100 million or more (in 

1995 dollars) in any one year by State, 

local, and tribal governments, in the 

aggregate, or by the private sector; such 

a mandate is deemed to be a ‘‘significant 

regulatory action.’’ The FAA currently 

uses an inflation-adjusted value of 

$140.8 million in lieu of $100 million. 

This final rule does not contain such a 

mandate, therefore, the requirements of 

Title II of the Act do not apply. 

Executive Order 13132, Federalism 

The FAA has analyzed this final rule 

under the principles and criteria of 

Executive Order 13132, Federalism. We 

determined that this action will not 

have a substantial direct effect on the 

States, on the relationship between the 

national Government and the States, or 

on the distribution of power and 

responsibilities among the various 

levels of government, and therefore does 

not have federalism implications. 

Environmental Analysis 

FAA Order 1050.1E defines FAA 

actions that are categorically excluded 

from preparation of an environmental 

assessment or environmental impact 

statement under the National 

Environmental Policy Act (NEPA) in the 

absence of extraordinary circumstances. 

We determined this rulemaking action 

qualifies for the categorical exclusion 

identified in Chapter 3, paragraph 312d, 

and involves no extraordinary 

circumstances. 

Regulations That Significantly Affect 

Energy Supply, Distribution, or Use 

The FAA has analyzed this final rule 

under Executive Order 13211, Actions 

Concerning Regulations that 

Significantly Affect Energy Supply, 

Distribution, or Use (May 18, 2001). We 

determined that it is not a ‘‘significant 

energy action’’ under the executive 

order and is not likely to have a 

significant adverse effect on the supply, 

distribution, or use of energy. 

Availability of Rulemaking Documents 

You can get an electronic copy using 

the Internet by— 

1. Searching the Federal eRulemaking 

Portal (http://www.regulations.gov); 

2. Visiting the FAA’s Regulations and 

Policies web page at http:// 

www.faa.gov/regulations_policies/; or 

3. Accessing the Government Printing 

Office’s web page at http:// 

www.gpoaccess.gov/fr/index.html. 

You can also get a copy by sending a 

request to the Federal Aviation 

Administration, Office of Rulemaking, 

ARM–1, 800 Independence Avenue, 

SW, Washington, DC 20591, or by 

calling (202) 267–9680. Make sure to 

identify the notice, amendment, or 

docket number of this rulemaking. 

Anyone may search the electronic 

form of all comments received into any 

of our dockets by the name of the 

individual submitting the comment (or 

signing the comment, if submitted on 

behalf of an association, business, labor 

union, etc.). You may review DOT’s 

complete Privacy Act statement in the 

Federal Register published on April 11, 

2000 (Volume 65, Number 70; Pages 

19477–78) or you may visit http:// 

DocketsInfo.dot.gov. 

Small Business Regulatory Enforcement 

Fairness Act 

The Small Business Regulatory 

Enforcement Fairness Act (SBREFA) of 

1996 requires the FAA to comply with 

small entity requests for information or 

advice about compliance with statutes 

and regulations within its jurisdiction. If 

you are a small entity and you have a 

question regarding this document, you 

may contact your local FAA official, or 

the person listed under the FOR FURTHER

INFORMATION CONTACT heading at the 

beginning of the preamble. You can find 

out more about SBREFA on the Internet 

at http://www.faa.gov/ 

regulations_policies/rulemaking/ 

sbre_act/. 

List of Subjects in 14 CFR Part 33 

Air transportation, Aircraft, Aviation 

safety, Safety. 

The Amendment 

In consideration of the foregoing, the 

Federal Aviation Administration 

amends Chapter I of Title 14, Code of 

Federal Regulations as follows: 

PART 33—AIRWORTHINESS 

STANDARDS: AIRCRAFT ENGINES 

■ 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 § 33.27 to read as follows: 

§ 33.27 Turbine, compressor, fan, and 

turbosupercharger rotor overspeed. 

(a) For each fan, compressor, turbine, 

and turbosupercharger rotor, the 

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42024 Federal Register / Vol. 76, No. 137 / Monday, July 18, 2011 / Rules and Regulations 

applicant must establish by test, 

analysis, or a combination of both, that 

each rotor will not burst when operated 

in the engine for 5 minutes at whichever 

of the conditions defined in paragraph 

(b) of this section is the most critical 

with respect to the integrity of such a 

rotor. 

(1) Test rotors used to demonstrate 

compliance with this section that do not 

have the most adverse combination of 

material properties and dimensional 

tolerances must be tested at conditions 

which have been adjusted to ensure the 

minimum specification rotor possesses 

the required overspeed capability. This 

can be accomplished by increasing test 

speed, temperature, and/or loads. 

(2) When an engine test is being used 

to demonstrate compliance with the 

overspeed conditions listed in 

paragraph (b)(3) or (b)(4) of this section 

and the failure of a component or 

system is sudden and transient, it may 

not be possible to operate the engine for 

5 minutes after the failure. Under these 

circumstances, the actual overspeed 

duration is acceptable if the required 

maximum overspeed is achieved. 

(b) When determining the maximum 

overspeed condition applicable to each 

rotor in order to comply with 

paragraphs (a) and (c) of this section, the 

applicant must evaluate the following 

rotor speeds taking into consideration 

the part’s operating temperatures and 

temperature gradients throughout the 

engine’s operating envelope: 

(1) 120 percent of the maximum 

permissible rotor speed associated with 

any of the engine ratings except oneengine-inoperative (OEI) ratings of less 

than 21⁄2 minutes. 

(2) 115 percent of the maximum 

permissible rotor speed associated with 

any OEI ratings of less than 21⁄2 minutes. 

(3) 105 percent of the highest rotor 

speed that would result from either: 

(i) The failure of the component or 

system which, in a representative 

installation of the engine, is the most 

critical with respect to overspeed when 

operating at any rating condition except 

OEI ratings of less than 21⁄2 minutes, or 

(ii) The failure of any component or 

system in a representative installation of 

the engine, in combination with any 

other failure of a component or system 

that would not normally be detected 

during a routine pre-flight check or 

during normal flight operation, that is 

the most critical with respect to 

overspeed, except as provided by 

paragraph (c) of this section, when 

operating at any rating condition except 

OEI ratings of less than 21⁄2 minutes. 

(4) 100 percent of the highest rotor 

speed that would result from the failure 

of the component or system which, in 

a representative installation of the 

engine, is the most critical with respect 

to overspeed when operating at any OEI 

rating of less than 21⁄2 minutes. 

(c) The highest overspeed that results 

from a complete loss of load on a 

turbine rotor, except as provided by 

paragraph (f) of this section, must be 

included in the overspeed conditions 

considered by paragraphs (b)(3)(i), 

(b)(3)(ii), and (b)(4) of this section, 

regardless of whether that overspeed 

results from a failure within the engine 

or external to the engine. The overspeed 

resulting from any other single failure 

must be considered when selecting the 

most limiting overspeed conditions 

applicable to each rotor. Overspeeds 

resulting from combinations of failures 

must also be considered unless the 

applicant can show that the probability 

of occurrence is not greater than 

extremely remote (probability range of 

10¥7 to 10¥9 per engine flight hour). 

(d) In addition, the applicant must 

demonstrate that each fan, compressor, 

turbine, and turbosupercharger rotor 

complies with paragraphs (d)(1) and 

(d)(2) of this section for the maximum 

overspeed achieved when subjected to 

the conditions specified in paragraphs 

(b)(3) and (b)(4) of this section. The 

applicant must use the approach in 

paragraph (a) of this section which 

specifies the required test conditions. 

(1) Rotor Growth must not cause the 

engine to: 

(i) Catch fire, 

(ii) Release high-energy debris 

through the engine casing or result in a 

hazardous failure of the engine casing, 

(iii) Generate loads greater than those 

ultimate loads specified in § 33.23(a), or 

(iv) Lose the capability of being shut 

down. 

(2) Following an overspeed event and 

after continued operation, the rotor may 

not exhibit conditions such as cracking 

or distortion which preclude continued 

safe operation. 

(e) The design and functioning of 

engine control systems, instruments, 

and other methods not covered under 

§ 33.28 must ensure that the engine 

operating limitations that affect turbine, 

compressor, fan, and turbosupercharger 

rotor structural integrity will not be 

exceeded in service. 

(f) Failure of a shaft section may be 

excluded from consideration in 

determining the highest overspeed that 

would result from a complete loss of 

load on a turbine rotor if the applicant: 

(1) Identifies the shaft as an engine 

life-limited-part and complies with 

§ 33.70. 

(2) Uses material and design features 

that are well understood and that can be 

analyzed by well-established and 

validated stress analysis techniques. 

(3) Determines, based on an 

assessment of the environment 

surrounding the shaft section, that 

environmental influences are unlikely 

to cause a shaft failure. This assessment 

must include complexity of design, 

corrosion, wear, vibration, fire, contact 

with adjacent components or structure, 

overheating, and secondary effects from 

other failures or combination of failures. 

(4) Identifies and declares, in 

accordance with § 33.5, any 

assumptions regarding the engine 

installation in making the assessment 

described above in paragraph (f)(3) of 

this section. 

(5) Assesses, and considers as 

appropriate, experience with shaft 

sections of similar design. 

(6) Does not exclude the entire shaft. 

(g) If analysis is used to meet the 

overspeed requirements, then the 

analytical tool must be validated to 

prior overspeed test results of a similar 

rotor. The tool must be validated for 

each material. The rotor being certified 

must not exceed the boundaries of the 

rotors being used to validate the 

analytical tool in terms of geometric 

shape, operating stress, and 

temperature. Validation includes the 

ability to accurately predict rotor 

dimensional growth and the burst 

speed. The predictions must also show 

that the rotor being certified does not 

have lower burst and growth margins 

than rotors used to validate the tool. 

Issued in Washington, DC, on June 30, 

2011. 

J. Randolph Babbitt, 

Administrator. 

[FR Doc. 2011–18002 Filed 7–15–11; 8:45 am] 

BILLING CODE 4910–13–P 

DEPARTMENT OF TRANSPORTATION 

Federal Aviation Administration 

14 CFR Part 39 

[Docket No. FAA–2011–0257; Directorate 

Identifier 2010–NM–122–AD; Amendment 

39–16741; AD 2011–14–06] 

RIN 2120–AA64 

Airworthiness Directives; Airbus Model 

A318, A319, A320, and A321 Series 

Airplanes 

AGENCY: Department of Transportation 

(DOT), Federal Aviation Administration 

(FAA). 

ACTION: Final rule. 

SUMMARY: We are superseding an 

existing airworthiness directive (AD) 

mstockstill on DSK4VPTVN1PROD with RULES