[Federal Register Volume 63, Number 101 (Wednesday, May 27, 1998)]
[Rules and Regulations]
[Pages 29070-29073]
From the Federal Register Online via the Government Publishing Office [www.gpo.gov]
[FR Doc No: 98-13999]



[[Page 29069]]

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Part III





Department of Transportation





_______________________________________________________________________



Federal Aviation Administration



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14 CFR Part 25



Braked Roll Conditions; Final Rule

  Federal Register / Vol. 63, No. 101 / Wednesday, May 27, 1998 / Rules 
and Regulations  

[[Page 29070]]



DEPARTMENT OF TRANSPORTATION

Federal Aviation Administration

14 CFR Part 25

[Docket No. 28643; Amdt. No. 25-97]
RIN 2120-AF83


Braked Roll Conditions

AGENCY: Federal Aviation Administration (FAA), DOT.

ACTION: Final rule.

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SUMMARY: This amendment to the airworthiness standards for transport 
category airplanes adds a new design standard that requires that the 
airplane be designed to withstand main landing gear maximum braking 
forces during ground operations. This amendment will ensure that the 
landing gear and fuselage are capable of withstanding the dynamic loads 
associated with the maximum dynamic braking condition. It also relieves 
a burden on industry by eliminating differences between the Federal 
Aviation Regulations (FAR) and European Joint Aviation Requirements 
(JAR), while maintaining a level of safety provided by the current 
regulations and industry practices.

EFFECTIVE DATE: June 26, 1998.

FOR FURTHER INFORMATION CONTACT: Jim Haynes, FAA, Airframe and 
Airworthiness Branch (ANM-115), Transport Airplane Directorate, 
Aircraft Certification Service, 1601 Lind Avenue SW., Renton, 
Washington 98055-4056; telephone (425) 227-2131; facsimile (425) 227-
1320.

SUPPLEMENTARY INFORMATION:

Availability of Final Rule

    An electronic copy of this document may be downloaded using a modem 
and suitable communications software from the FAA regulations section 
of the FedWorld electronic bulletin board service (telephone: 202-512-
1661) or the FAA's Aviation Rulemaking Advisory Committee Bulletin 
Board service (telephone: 800-FAA-ARAC).
    Internet users may reach the FAA's web page at http://www.faa.gov 
or the Federal Register's webpage at http://www.access.gpo.gov/su_docs 
for access to recently published rulemaking documents.
    Any person may obtain a copy of this final rule 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. Communications must identify the amendment 
number or document number of this final rule.
    Persons interested in being placed on the mailing list for future 
notices of proposed rulemaking and final rules should request from the 
above office a copy of Advisory Circular (AC) No. 11-2A, Notice of 
Proposed Rulemaking Distribution System, which describes the 
application procedure.

Small Entity Inquiries

    The Small Business Regulatory Enforcement Fairness Act of 1996 
(SBREFA) requires the FAA to report inquiries from small entities 
concerning information on, and advice about, compliance with statutes 
and regulations within the FAA's jurisdiction, including interpretation 
and application of the law to specific sets of facts supplied by a 
small entity.
    The FAA's definitions of small entities may be accessed through the 
FAA's web page (http://www.faa.gov.avr/arm/sbrefa.htm), by contacting a 
local FAA official, or by contacting the FAA's Small Entity Contact 
listed below.
    If you are a small entity and have a question, contact your local 
FAA official. If you do not know how to contact your local FAA 
official, you may contact Charlene Brown, Program Analyst Staff, Office 
of Rulemaking, ARM-27, Federal Aviation Administration, 800 
Independence Avenue, SW, Washington, DC 20591, 1-888-551-1594. Internet 
users can find additional information on SBREFA in the ``Quick Jump'' 
section of the FAA's web page at http://www.faa.gov and may send 
electronic inquiries to the following internet address: 9-AWA-
[email protected].

Background

    This amendment is based on Notice of Proposed Rulemaking (NPRM) 96-
10, which was published in the Federal Register on August 5, 1996 (61 
FR 40710). The notice was based on a need to protect the airframe 
structure from damage during hard application of the brakes.
    The current 14 CFR part 25 airworthiness standards, Sec. 25.493, 
and its predecessor rule, Sec. 4b.235(b) of the Civil Air Regulations 
(CAR), prescribe braked roll conditions that the airplane structure and 
landing gear must be designed to withstand during airplane taxiing with 
a constant (steady) application of brakes (``braked roll'' condition). 
The taxi condition is generally the most critical condition regarding 
nose gear and forward fuselage loading during the braking event, due to 
the increased braking coefficient of friction at low speeds and the 
lack of lift on the wings and lack of aerodynamic damping. Both rules 
treat the braked roll condition as a static equilibrium condition. 
Neither rule accounts for the dynamic loads on the nose gear and 
fuselage associated with pitch inertia of the airplane due to rapid 
application of main landing gear brakes. Adequate strength has been 
achieved on existing airplanes by application of other part 25 design 
requirements and by the manufacturers' need to comply with the more 
stringent British Civil Airworthiness Requirements (BCAR).
    For many years the BCAR have included a dynamic braking condition 
that requires that consideration be given to the maximum likely 
combination of dynamic vertical reaction and sudden increase in drag 
load that could occur on the nose gear as a result of sudden main gear 
braking while encountering obstacles. The BCAR address obstacles such 
as overruns onto semi-prepared surfaces during rejected takeoffs, 
running off the edge then back on to the runway during avoidance 
maneuvers, running over displaced or lowered edges of runway paving, 
and inadvertent use of runways under repair. In application of the BCAR 
requirement, it was found that U.S. designed airplanes generally have 
had adequate strength to meet this condition without requiring any 
modifications. However, this may not always be the case, especially if 
new airplane designs are significantly different from past conventional 
configurations in vertical and longitudinal mass distributions of fuel, 
payload, engine location, etc. As the takeoff weight increases with 
respect to landing weight, the dynamic braked roll condition can become 
more critical for the nose gear and fuselage. This amendment will 
ensure that all future airplanes will be provided with adequate 
strength in the fuselage and nose landing gear to carry these loads.
    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. The 
objective was to achieve common requirements for the certification of 
transport airplanes without a substantive change in the level of safety 
provided by the regulations. Other airworthiness authorities such as 
Transport Canada also participated in this process.
    In 1992, the harmonization effort was undertaken by the Aviation 
Rulemaking Advisory Committee (ARAC). A working group of industry and 
government structural loads specialists of Europe, the United States, 
and

[[Page 29071]]

Canada was chartered by notice in the Federal Register (58 FR 13819, 
March 15, 1993) to harmonize the design loads sections of Subpart C of 
part 25. The harmonization effort on the braked roll rule was 
accomplished and a specific proposal was recommended to the FAA by 
letter dated November 6, 1995. The FAA concurred with the 
recommendation, and published Notice 96-10 in the Federal Register on 
August 5, 1996, for public comment.
    Interested persons have been given an opportunity to participate in 
this rulemaking and due consideration has been given to all matters 
presented. Comments received in response to Notice 96-10 are discussed 
below.

Discussion of Comments

    The FAA received three comments in response to Notice 96-10. Two of 
these commenters support the proposal, one with comment, while the 
third commenter objects to the proposal.
    One commenter, representing the aviation industry, supports the 
proposal but expresses concern about possible interpretation of the 
rule. This commenter states that it is industry's belief that the 
proposed rule represented a harmonized position on both the rule and 
the interpretative advisory material; specifically, the commenter 
supports JAA interpretation and advisory material which allows use of a 
coefficient of friction less than 0.80, when substantiated, in the 
formula of Sec. 25.493(c). The commenter requests that this 
interpretation be clarified. The coefficient of friction of 0.80 
between the tire and ground surface has been used for structural design 
of the landing gear and structure since it was codified in the Civil 
Air Regulations (CAR Part 4b). The FAA has allowed a lower drag 
reaction in those cases where it can be substantiated that an effective 
drag force of 0.80 times the vertical reaction cannot be attained under 
any likely loading condition. This has generally been interpreted to 
mean that a lower drag force may be used where maximum brake torque is 
the limiting factor. This allowance is provided in the current 
regulation and is unchanged by this amendment. A value of 0.80 remains 
as the value of the coefficient of friction in the regulatory formula 
of Sec. 25.493(e).
    One commenter, an aircraft manufacturer, believes the proposed 
regulation is unnecessary because the braked roll condition is not the 
loading condition that determines the design of the nose gear and 
fuselage. The commenter states that a three point landing is typically 
the load condition which determines the design of the landing gear 
structure, which is far more severe than the braked roll conditions 
addressed in the notice. The FAA agrees that this may be true for most 
airplane designs; however, it is not always the case. The FAA considers 
the rule necessary to ensure proper landing gear designs for those 
airplanes that are affected by the braked roll condition.
    In view of the above, part 25 is amended as proposed in Notice 96-
10.

Regulatory Evaluation, Regulatory Flexibility Determination, 
International Trade Impact Assessment, and Unfunded Mandates 
Assessment

    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 effects of regulatory changes on small entities. Third, the 
Office of Management and Budget directs agencies to assess the effects 
of regulatory changes on international trade. 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 the private sector, of $100 million or more annually 
(adjusted for inflation). In conducting these analyses, which are 
summarized below (and available in the docket), the FAA has determined 
that this rule is not ``a significant regulatory action'' under section 
3(f) of Executive Order 12866 and therefore was not reviewed by the 
Office of Management and Budget. The rule is not considered significant 
under Department of Transportation Regulatory Policies and Procedures 
(44 FR 11034, February 26, 1979). In addition, for the reasons stated 
under the ``Regulatory Flexibility Determination,'' the ``International 
Trade Impact Assessment,'' and the ``Unfunded Mandates Assessment,'' 
the FAA certifies that this rule will not have a significant economic 
impact on a substantial number of small entities, will not constitute a 
barrier to international trade, and will not result in the expenditure 
by State, local, or tribal governments, in the aggregate, or by the 
private sector, of $100 million or more annually.

Regulatory Evaluation Summary

    As stated in the preamble to the notice, the rule change will 
codify current industry practice (thus maintaining at least the current 
level of safety) and will not impose additional costs on manufacturers 
of transport category airplanes. Adequate strength has been achieved on 
existing airplanes by application of other part 25 design requirements 
and by manufacturers' needs to comply with the more stringent BCAR in 
order to sell airplanes overseas. Moreover, by conforming Sec. 25.493 
of the FAR with Sec. 25.493 of the JAR, the new amendment will increase 
harmonization between American and European airworthiness standards and 
potentially reduce duplicate certification costs.

Regulatory Flexibility Determination

    The Regulatory Flexibility Act of 1980 (RFA) was enacted by 
Congress to ensure that small entities are not unnecessarily or 
disproportionately burdened by Government regulations. The RFA requires 
a Regulatory Flexibility Analysis, in which alternatives are identified 
and evaluated, if a rule is expected to have ``a significant economic 
impact on a substantial number of small entities.'' The Small Business 
Administration (SBA) has established standards for complying with RFA 
review requirements in Federal rulemaking actions; the standards 
specify small entity size by Standard Industrial Classification (SIC). 
The rule change will affect manufacturers of transport category 
airplanes produced under new type certificates. The SBA specifies a 
size threshold for classification as a small entity as 1,500 or fewer 
employees. Since the rule will impose no incremental costs on airplane 
manufacturers (and, additionally, no part 25 airplane manufacturer has 
1,500 or fewer employees), the rule change will not have a significant 
economic impact on a substantial number of small entities.

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 barriers affecting the 
export of American goods and services to foreign countries and barriers 
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

[[Page 29072]]

companies doing business in foreign markets, and foreign companies 
doing business in the United States.
    This rule 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 will be a 
positive step toward removing impediments to international trade.

Unfunded Mandates Assessment

    Title II of the Unfunded Mandates Reform Act of 1995 (the Act), 
enacted as Pub. L. 104-4 on March 22, 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 or more (adjusted annually for inflation) in any one year. 
Section 204(a) of the Act, 2 U.S.C. 1534(a), requires the Federal 
agency to develop an effective process to permit timely input by 
elected officers (or their designees) of State, local, and tribal 
governments on a proposed ``significant intergovernmental mandate.'' A 
``significant intergovernmental mandate'' under the Act is any 
provision in a Federal agency regulation that will impose an 
enforceable duty upon State, local, and tribal governments, in the 
aggregate, of $100 million (adjusted annually for inflation) in any one 
year. Section 203 of the Act, 2 U.S.C. 1533, which supplements section 
204(a), provides that before establishing any regulatory requirements 
that might significantly or uniquely affect small governments, the 
agency shall have developed a plan that, among other things, provides 
for notice to potentially affected small governments, if any, and for a 
meaningful and timely opportunity to provide input in the development 
of regulatory proposals.
    The FAA has determined that this rule does not contain a 
significant intergovernmental or private sector mandate as defined by 
the Act.

Federalism Implications

    The regulation amended herein will not have substantial direct 
effects 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, in 
accordance with Executive Order 12612, it is determined that this 
regulation will not have sufficient federalism implications to warrant 
the preparation of a Federalism Assessment.

International Civil Aviation Organization (ICAO) and Joint Aviation 
Regulations

    In keeping with U.S. obligations under the Convention on 
International Civil Aviation, it is FAA policy to comply with ICAO 
Standards and Recommended Practices to the maximum extent practicable. 
The FAA has determined that this rule does not conflict with any 
international agreement of the United States.

Paperwork Reduction Act

    In accordance with the Paperwork Reduction Act of 1995 (44 U.S.C. 
3507(d)), there are no reporting or recordkeeping requirements 
associated with this rule.

Regulations Affecting Intrastate 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 intrastate 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 final 
rule applies to the certification of future designs of transport 
category airplanes and their subsequent operation, it could affect 
intrastate aviation in Alaska. The Administrator has considered the 
extent to which Alaska is not served by transportation modes other than 
aviation, and how the final rule could have been applied differently to 
intrastate operations in Alaska. However, the Administrator has 
determined that airplanes operated solely in Alaska would present the 
same safety concerns as all other affected airplanes; therefore, it 
would be inappropriate to establish a regulatory distinction for the 
intrastate operation of affected airplanes in Alaska.

List of Subjects in 14 CFR Part 25

    Aircraft, Aviation safety, Reporting and recordkeeping 
requirements.

Adoption of the Amendment

    In consideration of the foregoing, the Federal Aviation 
Administration (FAA) amends 14 CFR part 25 of the Federal Aviation 
Regulations (FAR) as follows:

PART 25--AIRWORTHINESS STANDARDS: TRANSPORT CATEGORY AIRPLANES

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

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

    2. Section 25.493 is amended by revising paragraph (c) and by 
adding new paragraphs (d) and (e) to read as follows:


Sec. 25.493  Braked roll conditions.

* * * * *
    (c) A drag reaction lower than that prescribed in this section may 
be used if it is substantiated that an effective drag force of 0.8 
times the vertical reaction cannot be attained under any likely loading 
condition.
    (d) An airplane equipped with a nose gear must be designed to 
withstand the loads arising from the dynamic pitching motion of the 
airplane due to sudden application of maximum braking force. The 
airplane is considered to be at design takeoff weight with the nose and 
main gears in contact with the ground, and with a steady-state vertical 
load factor of 1.0. The steady-state nose gear reaction must be 
combined with the maximum incremental nose gear vertical reaction 
caused by the sudden application of maximum braking force as described 
in paragraphs (b) and (c) of this section.
    (e) In the absence of a more rational analysis, the nose gear 
vertical reaction prescribed in paragraph (d) of this section must be 
calculated according to the following formula:

[GRAPHIC] [TIFF OMITTED] TR27MY98.017

Where:

VN=Nose gear vertical reaction.
WT=Design takeoff weight.
A=Horizontal distance between the c.g. of the airplane and the nose 
wheel.
B=Horizontal distance between the c.g. of the airplane and the line 
joining the centers of the main wheels.
E=Vertical height of the c.g. of the airplane above the ground in the 
1.0 g static condition.
=Coefficient of friction of 0.80.
f=Dynamic response factor; 2.0 is to be used unless a lower factor is 
substantiated. In the absence of other information, the dynamic 
response factor f may be defined by the equation:

[GRAPHIC] [TIFF OMITTED] TR27MY98.018

Where:
 is the effective critical damping ratio of the rigid body 
pitching mode about the main landing gear effective ground contact 
point.


[[Page 29073]]


    Issued in Washington, DC, on May 18, 1998.
Jane F. Garvey,
Administrator.
[FR Doc. 98-13999 Filed 5-26-98; 8:45 am]
BILLING CODE 4910-13-P