[Federal Register Volume 65, Number 243 (Monday, December 18, 2000)]
[Proposed Rules]
[Pages 79278-79282]
From the Federal Register Online via the Government Publishing Office [www.gpo.gov]
[FR Doc No: 00-31927]



[[Page 79277]]

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Part IV





Department of Transportation





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Federal Aviation Administration



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14 CFR Part 25



Revision of Braking Systems; Airworthiness Standards to Harmonize With 
European Airworthiness Standards for Transport Category Airplanes; 
Proposed Rule

  Federal Register / Vol. 65, No. 243 / Monday, December 18, 2000 / 
Proposed Rules  

[[Page 79278]]


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DEPARTMENT OF TRANSPORTATION

Federal Aviation Administration

14 CFR Part 25

[Docket No. FAA-1999-6063; Notice No. 99-16A]
RIN 2120-AG80


Revision of Braking Systems; Airworthiness Standards To Harmonize 
With European Airworthiness Standards for Transport Category Airplanes

AGENCY: Federal Aviation Administration, DOT.

ACTION: Supplemental notice of proposed rulemaking, (SNPRM).

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SUMMARY: This document seeks public comment on changes proposed as a 
result of the comments received on Notice No. 99-16. The changes 
proposed in this supplemental notice would require an additional 
dynamometer test during brake qualification, namely, an accelerate-stop 
test with the brake heat sink in a new condition (also called a new 
brake rejected takeoff (RTO) test) for part 25 transport category 
airplanes. The new proposed brake test could result in a minimal cost 
increase for some part 25 small airplanes. These changes are intended 
to benefit the public interest by standardizing certain requirements, 
concepts, and procedures in the airworthiness standards without 
reducing, but potentially enhancing, the current level of safety.

DATES: Comments must be received on or before February 16, 2001.

ADDRESSES: Address your comments to the Docket Management System, U.S. 
Department of Transportation, Room PL 401, 400 Seventh Street, NW, 
Washington, DC 20590-0001. You must identify the docket number FAA-
1999-6063 at the beginning of your comments, and you should submit two 
copies of your comments. If you wish to receive confirmation that FAA 
has received your comments, include a self addressed, stamped postcard.
    You may also submit comments through the Internet to: http://dms.dot.gov. You may review the public docket containing comments to 
these proposed regulations in person in the Docket Office between 9:00 
a.m. and 5:00 p.m., on the plaza level of the Nassif Building at the 
Department of Transportation at the above address. Also, you may review 
public dockets on the Internet at http://dms.dot.gov.

FOR FURTHER INFORMATION CONTACT: Mahinder K. Wahi, FAA, Propulsion/
Mechanical Systems Branch, ANM-112, Transport Airplane Directorate, 
1601 Lind Avenue SW., Renton, WA 98055-4056; telephone (425) 227-2142; 
facsimile (425) 227-1320.

SUPPLEMENTARY INFORMATION:

Comments Invited

    Interested persons are invited to participate in the making of the 
proposed rule by submitting such written data, views, or arguments as 
they may desire. Comments relating to the environmental, energy, 
federalism, or economic impact that might result from adopting the 
proposals in this notice are also invited. Substantive comments should 
be accompanied by cost estimates. Commenters must identify the 
regulatory docket or notice number and submit comments in duplicative 
to the DOT Rules Docket address specified above.
    All comments received, as well as a report summarizing each 
substantive public contact with FAA personnel concerning this 
rulemaking, will be filed in the docket. The Docket is available for 
public inspection before and after the comment closing date.
    All comments received on or before the closing date will be 
considered by the Administrator before taking action on this proposed 
rulemaking. Comments filed late will be considered as far as possible 
without incurring expense or delay. The proposals contained in this 
notice may be changed in light of the comments received.
    Commenters wishing the FAA to acknowledge receipt of their comments 
submitted in response to this notice must include a pre-addressed, 
stamped postcard on which the following statement is made: ``Comments 
to Docket No. FAA-1999-6063.'' The postcard will be date stamped and 
mailed to the commenter.

Availability of the SNPRM

    You can get an electronic copy using the Internet by taking the 
following steps:
    (1) Go to the search function of the Department of Transportation's 
electronic Docket Management System (DMS) Web page (http://dms.dot.gov/search).
    (2) On the search page type in the last four digits of the Docket 
number shown at the beginning of this notice. Click on ``search.''
    (3) On the next page, which contains the Docket summary information 
for the Docket you selected, click on the final rule.
    You can also get an electronic copy using the Internet through 
FAA's web page at http://www.faa.gov/avr/arm/nprm/nprm.htm or the 
Federal Register's web page at http://www.access.gpo.gov/su_docs/aces/aces140.html.
    You can also get a copy by submitting 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 amendment number or docket number of this notice.

Background

    On August 10, 1999, the the FAA issued an NPRM titled ``Revision of 
Braking Systems Airworthiness Standards To Harmonize With European 
Airworthiness Standards for Transport Category Airplanes,'' Notice No. 
99-16 (64 FR 43570), and two Notices of Availability, ``Proposed TSO-
C135, Transport Airplane Wheels and Wheel and Brake Assemblies,'' and 
``Proposed Advisory Circular (AC) 25.735-1X, Brakes and Braking Systems 
Certification Tests and Analysis.'' The related background material 
leading to Notice No. 99-16 and the notices of availability is as 
follows:
    In 1988, the FAA, in cooperation with the JAA and other 
organizations representing the American and European aerospace 
industries, began a process to harmonize the airworthiness requirements 
of the United States and the airworthiness requirements of Europe, 
especially in the areas of Flight Test and Structures.
    Starting in 1992, the FAA's harmonization effort for various 
systems-related airworthiness requirements was undertaken by the ARAC. 
A working group of industry and government braking systems specialists 
of Europe, the United States, and Canada was chartered by notice in the 
Federal Register (59 FR 30080, June 10, 1994). The working group was 
tasked to develop a harmonized standard, such as a Technical Standard 
Order (TSO), for approval of wheels and brakes to be installed on 
transport category airplanes and to develop a draft notice of proposed 
rulemaking (NPRM), with supporting economic and other required 
analyses, and/or any other related guidance material or collateral 
documents, such as advisory circulars, concerning new or revised 
requirements and the associated test conditions for wheels, brakes and 
braking systems, installed in transport category airplanes 
(Secs. 25.731 and 25.735).
    The harmonization task was completed by the working group and 
recommendations were submitted to the FAA by a letter dated May 1, 
1998. The FAA concurred with the

[[Page 79279]]

recommendations and proposed them in Notice No. 99-16. A notice of 
availability of proposed TSO-C135 and request for comments and a notice 
of availability of proposed AC 25.735-1X and request for comments were 
also published in the Federal Register on August 10, 1999 (64 FR 
43579). On August 25, 1999, the JAA issued two Notices of Proposed 
Amendment (NPA) 25D-291 and NPA TSO-7: ``Brakes and Braking Systems'' 
that included the proposed advisory material AMJ 25.735. The amendments 
proposed in NPA 25D-291 and the advisory material proposed in AMJ 
25.735 were substantively the same as the amendments proposed by the 
Notice No. 99-16 and the advisory material in proposed AC 25.735-1X. 
The NPA TSO-7 was substantively the same as proposed TSO-C135.
    As a result, the FAA and JAA each received a set of comments from 
the public in response to the proposed rule, the proposed TSO, and the 
proposed AC. These two sets of comments are interlinked and addressed 
jointly by the FAA in preparing this SNPRM.

Discussion of Comments: Notice 99-16

    Twenty-one commenters responded to the request for comments 
contained in Notice No. 99-16, the notices of availability of proposed 
TSO-C135 and AC 25.735-1, and the corresponding JAA documents NPA 25D-
291, NPA TSO-7, and AMJ 25.735. Comments were received from eight (8) 
foreign and domestic airplane and brake manufacturers, nine (9) foreign 
airworthiness authorities, one operator and three (3) foreign and 
domestic industry organizations. The majority of the commenters agree 
with the proposal and recommend its adoption. However, some commenters 
disagree with the proposal while providing alternative proposals that 
appear to merit further consideration by the ARAC. Therefore, the FAA 
tasked the ARAC Braking Systems Harmonization Working Group (HWG) by 
letter dated February 8, 2000, to consider the comments and provide 
recommendations for the disposition of the comments along with any 
recommendations for changes to the proposal. Proposal 11 is the only 
proposal relevant to this SNPRM. The disposition of the comments below 
is based on the agreement reached by the HWG.

Proposal 11, Sec. 25.735(f)

    The proposed paragraph Sec. 25.735(f) in Notice No. 99-16 reads as 
follows:
    (f) Kinetic energy capacity. The design landing stop, the maximum 
kinetic energy accelerate-stop, and the most severe landing stop brake 
kinetic energy absorption requirements of each wheel and brake assembly 
must be determined. It must be substantiated by dynamometer testing 
that, at the declared fully worn limit(s) of the brake heat sink, the 
wheel and brake assemblies are capable of absorbing not less than these 
levels of kinetic energy. Energy absorption rates defined by the 
airplane manufacturer must be achieved. These rates must be equivalent 
to mean decelerations not less than 10 fps\2\ for the design landing 
stop and 6 fps\2\ for the maximum kinetic energy accelerate stop. The 
most severe landing stop need not be considered for extremely 
improbable failure conditions or if the maximum kinetic energy 
accelerate-stop energy is more severe. Design landing stop is an 
operational landing stop at maximum landing weight. Maximum kinetic 
energy accelerate-stop is a rejected takeoff for the most critical 
combination of airplane takeoff weight and speed. Most severe landing 
stop is a stop at the most critical combination of airplane landing 
weight and speed.
    Comment: One commenter states that as proposed, Sec. 25.735(f) is 
difficult to read and contains too many separate requirements in 
itself. It could create undue difficulties during the finding of 
compliance. It is suggested that the paragraph be re-arranged such 
that:
     There is a distinct sub-paragraph that can be identified 
for the requirement for the determination of the levels of kinetic 
energy and the energy absorption rates. This paragraph should indicate 
that three cases are to be considered (design landing stop, accelerate-
stop, and most severe landing stop). This sub-paragraph could also 
mention the caveats about the need to consider, or not consider, during 
testing the most severe landing stop.
     There is a distinct sub-paragraph for the requirement for 
the wheel and brake assembly to meet the levels of kinetic energy.
     There is a distinct sub-paragraph for the requirement for 
the wheel and brake assembly to meet the energy absorption rates.
     The definitions of the three stop cases (the last 9 lines 
of the currently proposed paragraph, starting with: `` . . . Design 
landing stop is an operational . . . '') are taken out of the 
requirement and placed in the proposed AC 25.735-1X.
    The FAA concurs that rearranging Sec. 25.735(f) into three distinct 
sub-paragraphs clarifies the requirement. The FAA, however, decided 
that it is more appropriate to retain the definitions as part of the 
regulatory text, since this is the only place where these terms are 
identified.
    The text of this paragraph is divided into three subparagraphs 
f(1), f(2), and f(3) with appropriate headings. The subparagraphs cover 
each of the three tests and include the definitions.
    Comment: Two commenters suggest adding a requirement that the 
accelerate-stop test, reference: paragraph 3.3.3.2 of the proposed TSO-
C135, and Sec. 25.735(f) of Notice No. 99-16, must be completed on both 
a new brake and a fully worn brake. The fully worn brake is the worst 
case condition for energy absorption capability, however, the new brake 
condition is the worst case condition for performance for some heat 
sink materials. (The heat sink is the mass of the brake that is 
primarily responsible for absorbing energy during a stop. For a typical 
brake, this would consist of the stationary and rotating disc 
assemblies.)
    The FAA concurs with this comment. Applicable text in the TSO-C135 
paragraph 3.3.3.2, and the new Sec. 25.735(f)(2) in this SNPRM add a 
new brake accelerate-stop test requirement with the new brake defined 
as a brake worn no more than 5 percent of its usable wear range. The 
accelerate-stop applicable portion of Sec. 25.735(f) text, Notice No. 
99-16, is revised from ``It must be substantiated by dynamometer 
testing that, at the declared fully-worn limit(s) of the brake heat 
sink, the wheel and brake assemblies are capable of absorbing not less 
than these levels of kinetic energy'' to ``(f)(2): It must be 
substantiated by dynamometer testing that the wheel, brake, and tire 
assembly is capable of absorbing not less than this level of kinetic 
energy throughout the defined wear range of the brake.'' Although, not 
a part of the TSO, large airplane manufacturers currently require a new 
brake RTO test as part of brake qualification. Small airplane 
manufacturers may experience a cost increase of $20,000 per 
certification.

The New Proposal

    The revised proposed rule reads as follows:
    (f) Kinetic energy capacity
    (1) Design landing stop: The design landing stop is an operational 
landing stop at maximum landing weight. The design landing stop brake 
kinetic energy absorption requirement of each wheel, brake, and tire 
assembly must be determined. It must be substantiated by dynamometer 
testing that the wheel, brake and tire assembly is capable of absorbing 
not less than this level of kinetic energy throughout the defined wear 
range of the brake. The energy absorption rate derived from the

[[Page 79280]]

airplane manufacturer's braking requirements must be achieved. The mean 
deceleration must not be less than 10 fps\2\.
    (2) Maximum kinetic energy accelerate-stop: The maximum kinetic 
energy accelerate-stop is a rejected takeoff for the most critical 
combination of airplane takeoff weight and speed. The accelerate-stop 
brake kinetic energy absorption requirement of each wheel, brake, and 
tire assembly must be determined. It must be substantiated by 
dynamometer testing that the wheel, brake, and tire assembly is capable 
of absorbing not less than this level of kinetic energy throughout the 
defined wear range of the brake. The energy absorption rate defined by 
the airplane manufacturer must be achieved. The mean deceleration must 
not be less than 6 fps\2\.
    (3) Most severe landing stop: The most severe landing stop is a 
stop at the most critical combination of airplane landing weight and 
speed. The most severe landing stop brake kinetic energy absorption 
requirement of each wheel, brake, and tire assembly must be determined. 
It must be substantiated by dynamometer testing that, at the declared 
fully worn limit(s) of the brake heat sink, the wheel, brake and tire 
assembly is capable of absorbing not less than this level of kinetic 
energy. The most severe landing stop need not be considered for 
extremely improbable failure conditions or if the maximum kinetic 
energy accelerate-stop energy is more severe.
    The rulemaking proposal contained in this supplemental notice is 
based on a recommendation developed by the Braking Systems 
Harmonization Working Group, and presented to the FAA by the ARAC as a 
recommendation.

Paperwork Reduction Act

    In accordance with the Paperwork Reduction Act of 1995 (44 U.S.C. 
3507(d)), the FAA has determined that there are no requirements for 
information collection associated with this proposed rule.

Compatibility with ICAO Standards

    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. For this 
SNPRM, the FAA has determined that there are no ICAO Standards and 
Recommended Practices that correspond to these proposed regulations.

Regulatory Evaluation Summary, 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 directs that each 
federal agency shall 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 requires agencies 
to analyze the economic effect of regulatory changes on small entities. 
Third, the Trade Agreements Act (19 U.S.C. 2531-2533) 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, to use those standards as the basis 
of U.S. standards. Fourth, Title II of the Unfunded Mandates Reform Act 
of 1995 requires each Federal agency, to the extent permitted by law, 
to prepare a written assessment of the effects of any Federal mandate 
in a proposed or final agency rule that may result in the expenditure 
by State, local, and tribal governments, in the aggregate, or by the 
private sector, of $100 million in any one year. In conducting these 
analyses, the FAA has determined that this supplemental proposal: (1) 
Would generate benefits that justify its costs and is not ``a 
significant regulatory action'' as defined in Executive Order 12866 or 
in the Department of Transportation's Regulatory Policies and 
Procedures; (2) would not have a significant impact on a substantial 
number of small entities; (3) would not constitute a barrier to 
international trade, and (4) does not contain a Federal 
intergovernmental or private sector mandate that exceeds $100 million 
in any one year.
    These analyses, available in the docket, are summarized below. All 
estimates are expressed in year 2000 dollars.

Regulatory Evaluation Summary

Summary of Major Economic Issues in NPRM 99-16
    Of several revisions proposed for 14 CFR 25.735, only one, proposal 
11, was expected to impose additional costs, estimated at $20,000 to 
$60,000 (the latter upper estimate has been reduced to $40,000) for 
part 25 large airplanes and $20,000 (as explained below, the latter 
estimate has been increased to a range of $20,000 to $40,000) for part 
25 small airplanes. Most of the changes codify current industry 
practice or conform 14 CFR 25.735 to corresponding sections of the JAR. 
The resulting regulatory harmonization would eliminate unnecessary 
duplication of airworthiness requirements, thus reducing manufacturers' 
certification costs.
    None of the commenters disputes FAA's estimates of specific 
incremental certification costs. One commenter, however, questions 
FAA's contention that costs would be balanced by the savings from rule 
harmonization, and further objects to the vagueness of the expected 
safety benefits. The FAA disagrees with the latter commenter's synopsis 
of the benefits' conclusion in the NPRM. The FAA did not contend that 
quantified benefits from averted future accidents alone would 
economically justify the proposed rule. Although total harmonization 
savings were not specified, the FAA nevertheless stated that 
``according to one manufacturer, cost savings from harmonization * * * 
would be equal to or greater than the maximum incremental cost of 
$60,000.'' The FAA also noted that ``potential safety benefits 
resulting from specification of minimum accepted standards would 
supplement these cost savings.'' In addition, even though none of the 
previous accidents would have been directly preventable by the proposed 
amendments, ``different designs in future type certifications, however, 
could present other problems (unexpected) and raise future accident 
rates.''
    Notwithstanding the above, since publication of Notice 99-16, the 
FAA has contacted industry sources to obtain estimates of harmonization 
cost savings attributable to the revisions originally proposed in the 
Notice. These cost savings would be, at a minimum, between $50,000 and 
$75,000 for a part 25 small airplane type certification and $100,000 to 
$300,000 for a part 25 large airplane type certification. These 
harmonization benefits would exceed the incremental costs of all the 
revisions specified in the NPRM as well as the costs attributable to 
the SNPRM change.
Supplemental Change and Associated Costs and Benefits
    The proposed dynamometer test, also called a new brake rejected 
takeoff (RTO) test, is currently conducted by brake manufacturers as 
specified by large airplane manufacturers during brake qualification 
testing and is considered standard industry practice. For some 
manufacturers of part 25 small airplanes, however, the proposed test 
could result in a cost increase of

[[Page 79281]]

$20,000 per type certification (thus increasing incremental costs for 
proposal 11 in the NPRM from an estimated $20,000 to a range of $20,000 
to $40,000). This incremental but nonrecurring cost for some 
manufacturers of part 25 small airplanes would easily be offset by the 
harmonization cost savings cited earlier. Any potential safety benefits 
from avoiding even one minor accident would add to such benefits. The 
FAA, therefore, finds the additional change to proposal 11 to be cost 
beneficial for both part 25 small and large airplane manufacturers.

Regulatory Flexibility Determination

    The Regulatory Flexibility Act of 1980 (RFA) establishes as a 
principle of regulatory issuance that agencies shall endeavor, 
consistent with the objective of the rule and of applicable statutes, 
to fit regulatory and informational requirements to the scale of the 
business, organizations, and governmental jurisdictions subject to 
regulation. To achieve that principle, the Act requires agencies to 
solicit and consider flexible regulatory proposals and to explain the 
rationale for their actions. The Act covers a wide range of small 
entities, including small businesses, not-for-profit organizations, and 
small governmental jurisdictions.
    Agencies must perform a review to determine whether a proposed or 
final rule will have a ``significant economic impact on a substantial 
number of small entities.'' If the determination is that it will, the 
agency must prepare a regulatory flexibility analysis as described in 
the RFA.
    However, if an agency determines that a proposed or final rule is 
not expected to have a significant 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.
    This SNPRM would affect manufacturers of transport category 
airplanes produced under future new airplane type certifications. For 
airplane manufacturers, a small entity is one with 1,500 or fewer 
employees. Since no part 25 airplane manufacturer has 1,500 or fewer 
employees, the FAA certifies that the rule will not have a significant 
economic impact on a substantial number of small manufacturers.

International Trade Impact Assessment

    Consistent with the Administration's belief in the general 
superiority, desirability, and efficacy of free trade, it is the policy 
of the Administrator to remove or diminish, to the extent feasible, 
barriers to international trade, including both barriers affecting the 
export of American goods and services to foreign countries and those 
affecting the import of foreign goods and services into the United 
States.
    In accordance with that policy, the FAA is committed to develop as 
much as possible its aviation standards and practices in harmony with 
its trading partners. Significant cost savings can result from this, 
both to United States' companies doing business in foreign markets, and 
foreign companies doing business in the United States.
    The subject proposal is a direct action to respond to this policy 
by increasing the harmonization of the U.S. Federal Aviation 
Regulations with the European Joint Aviation Requirements. The result 
would be a positive step toward removing impediments to international 
trade.

Unfunded Mandates Reform Act

    Title II of the Unfunded Mandates Reform Act of 1995 (the Act), 
enacted as Public Law 104-4 on March 22, 1995 (the Act), codified in 2 
U.S.C. 1501-1571, requires each Federal agency, to the extent permitted 
by law, to prepare a written assessment of the effects of any Federal 
mandate in a proposed or final agency rule that may result in the 
expenditure by State, local, and tribal governments, in the aggregate, 
or by the private sector, of $100 million or more (adjusted annually 
for inflation) in any one year.
    This supplemental proposal does not contain a Federal 
intergovernmental or private sector mandate that exceeds $100 million 
in any one year. Therefore, the requirements of Title II of the 
Unfunded Mandates Reform Act of 1995 do not apply.

Regulations Affecting Interstate Aviation in Alaska

    Section 1205 of the FAA Reauthorization Act of 1996 (110 Stat. 
3213) requires the Administrator when modifying regulations in title 14 
of the CFR in a manner affecting interstate aviation in Alaska, to 
consider the extent to which Alaska is not served by transportation 
modes other than aviation, and to establish such regulatory 
distinctions as he or she considers appropriate. Because this proposed 
rule would apply to the certification of future designs of transport 
category airplanes and their subsequent operation, it could, if 
adopted, affect interstate aviation in Alaska. The FAA therefore 
specifically requests comments on whether there is justification for 
applying the proposed rule differently in interstate operations in 
Alaska.

Executive Order 13132, Federalism

    The FAA has analyzed this proposed rule under the principles and 
criteria of Executive Order 13132, Federalism. We determined that this 
action would 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. Therefore, we determined that this proposed rule does not 
have federalism implications.

Environmental Analysis

    FAA Order 1050.1D defines FAA actions that may be categorically 
excluded from preparation of a National Environmental Policy Act (NEPA) 
environmental impact statement. In accordance with FAA Order 1050.1D, 
appendix 4, paragraph 4(j), this proposed rulemaking action qualifies 
for a categorical exclusion.

Energy Impact

    The energy impact of the notice has been assessed in accordance 
with the Energy Policy and Conservation Act (EPCA) Public Law 94-163, 
as amended (42 U.S.C. 6362) and FAA Order 1053.1. It has been 
determined that the notice is not a major regulatory action under the 
provisions of the EPCA.

List of Subjects in 14 CFR Part 25

    Aircraft, Aviation safety, Reporting and recordkeeping requirements

The Proposed Amendment

    In consideration of the foregoing, the Federal Aviation 
Administration proposes to amend part 25 of Title 14, Code of Federal 
Regulations, as follows:

PART 25--AIRWORTHINESS STANDARDS: TRANSPORT CATEGORY AIRPLANES

    1. The authority citation for part 25 continues to read as follows:

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

    2. Amend Sec. 25.735 for revising the heading and paragraph (f) to 
read as follows:


Sec. 25.735  Brakes and braking systems.

* * * * *
    (f) Kinetic energy capacity
    (1) Design landing stop: The design landing stop is an operational 
landing stop at maximum landing weight. The design landing stop brake 
kinetic energy

[[Page 79282]]

absorption requirement of each wheel, brake, and tire assembly must be 
determined. It must be substantiated by dynamometer testing that the 
wheel, brake and tire assembly is capable of absorbing not less than 
this level of kinetic energy throughout the defined wear range of the 
brake. The energy absorption rate derived from the airplane 
manufacturer's braking requirements must be achieved. The mean 
deceleration must not be less than 10 fps.\2\
    (2) Maximum kinetic energy accelerate-stop: The maximum kinetic 
energy accelerate-stop is a rejected takeoff for the most critical 
combination of airplane takeoff weight and speed. The accelerate-stop 
brake kinetic energy absorption requirement of each wheel, brake, and 
tire assembly must be determined. It must be substantiated by 
dynamometer testing that the wheel, brake, and tire assembly is capable 
of absorbing not less than this level of kinetic energy throughout the 
defined wear range of the brake. The energy absorption rate defined by 
the airplane manufacturer must be achieved. The mean deceleration must 
not be less than 6 fps.\2\
    (3) Most severe landing stop: The most severe landing stop is a 
stop at the most critical combination of airplane landing weight and 
speed. The most severe landing stop brake kinetic energy absorption 
requirement of each wheel, brake, and tire assembly must be determined. 
It must be substantiated by dynamometer testing that, at the declared 
fully worn limit(s) of the brake heat sink, the wheel, brake and tire 
assembly is capable of absorbing not less than this level of kinetic 
energy. The most severe landing stop need not be considered for 
extremely improbable failure conditions or if the maximum kinetic 
energy accelerate-stop energy is more severe.
* * * * *

    Issued in Renton, Washington on December 4, 2000.
John J. Hickey,
Manager, Transport Airplane Directorate, Aircraft Certification 
Service.
[FR Doc. 00-31927 Filed 12-15-00; 8:45 am]
BILLING CODE 4910-13-U