[Federal Register Volume 64, Number 117 (Friday, June 18, 1999)]
[Proposed Rules]
[Pages 32978-32981]
From the Federal Register Online via the Government Publishing Office [www.gpo.gov]
[FR Doc No: 99-15381]
[[Page 32977]]
_______________________________________________________________________
Part V
Department of Transportation
_______________________________________________________________________
Federal Aviation Administration
_______________________________________________________________________
14 CFR Part 25
Revised Landing Gear Shock Absorption Test Requirements and Proposed
Advisory Circular 25.723-1, Shock Absorption Test; Proposed Rule and
Notice
Federal Register / Vol. 64, No. 117 / Friday, June 18, 1999 /
Proposed Rules
[[Page 32978]]
DEPARTMENT OF TRANSPORTATION
Federal Aviation Administration
14 CFR Part 25
[Docket No. FAA-1999-5835; Notice No. 99-08]
RIN 2120-AG72
Revised Landing Gear Shock Absorption Test Requirements
AGENCY: Federal Aviation Administration (FAA), DOT.
ACTION: Notice of proposed rulemaking (NPRM).
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SUMMARY: This document proposes to revise the landing gear shock
absorption test requirements for transport category airplanes by
incorporating changes developed in cooperation with the Joint Aviation
Authorities (JAA) of Europe and the U.S. and European aviation industry
through the Aviation Rulemaking Advisory Committee (ARAC). This action
is necessary because the increasing complexity of landing gear shock
absorption systems and the improvements in other requirements
concerning landing loads have rendered the current requirements
inconsistent and outdated. In addition, differences between the current
United States and European requirements impose unnecessary costs on
airplane manufacturers. These proposals are intended to update the
landing gear requirements to be consistent with other requirements, to
reflect modern technology, and to achieve common requirements and
language between the Federal Aviation Regulations and the European
Joint Aviation Requirements (JAR) without reducing the level of safety
provided by the regulations and industry practices.
DATES: Comments must be received on or before October 18, 1999.
ADDRESSES: Comments on this proposal may be mailed in duplicate to:
U.S. Department of Transportation, Dockets, Docket No. FAA-1999-5835,
400 Seventh Street SW., Room Plaza 401, Washington, D.C. 20590.
Comments may also be submitted electronically to the following address:
[email protected] Comments may be examined in Room Place 401 between
10 a.m. and 5 p.m., weekdays, except Federal holidays. In addition, the
FAA is maintaining an information docket of comments in the Transport
Airplane Directorate (ANM-100), FAA, 1601 Lind Avenue SW., Renton, WA
98055-4056. Comments in the information docket may be examined
weekdays, except Federal holidays, between 7:30 a.m. and 4 p.m.
FOR FURTHER INFORMATION CONTACT: James Haynes, Airframe/Cabin Safety
Branch, ANM-115, Transport Airplane Directorate, Aircraft Certification
Service, FAA, 1601 Lind Avenue, SW., Renton, WA 98055-4056; telephone
(425) 227-2131.
SUPPLEMENTARY INFORMATION:
Comments Invited
Interested persons are invited to participate in this proposed
rulemaking by submitting such written data, views, or arguments as they
may desire. Comments relating to any environmental, energy, or economic
impact that might result from adopting the proposals contained in this
action are invited. Substantive comments should be accompanied by cost
estimates. Commenters should identify the regulatory docket or notice
number and submit comments in duplicate to the Docket address above.
All comments received on or before the closing date for comments will
be considered by the Administrator before taking action on this
proposed rulemaking. Late filed comments will be considered to the
extent practicable. The proposals contained in this action may be
changed in light of comments received. All comments received will be
available in the Docket, both before and after the comment period
closing date, for examination by interested persons. A report
summarizing each substantive public contact with FAA personnel
concerning this rulemaking will be filed in the docket. Persons wishing
the FAA to acknowledge receipt of their comments must submit with those
comments a self-addressed, stamped postcard on which the following
statement is made: ``Comments to Docket No. FAA-1999-5835.'' The
postcard will be date/time stamped and returned to the commenter.
Availability of NPRM
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: 703-321-
3339), the Government Printing Office's electronic bulletin board
service (telephone: 202-512-1661), or the FAA's Aviation Rulemaking
Advisory Committee Bulletin Board service (telephone: 800-322-2722 or
202-267-5948).
Internet users may reach the FAA's web page at http://www.faa.gov/
avr/arm/nprm.htm or the Government Printing Office's web page at http:/
/www.access.gpo.gov/nara for access to recently published rulemaking
documents.
Any person may obtain a copy of this document 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 docket or notice
number of this NPRM. Persons interested in being placed on a mailing
list for future rulemaking documents should also request a copy of
Advisory Circular No. 11-2A, Notice of Proposed Rulemaking Distribution
System, which describes the application procedure.
Background
The manufacturing, marketing and certification of transport
airplanes is increasingly an international endeavor. In order for U.S.
manufacturers to export transport airplanes to other countries the
airplane must be designed to comply, not only with the U.S.
airworthiness requirements for transport airplanes (14 CFR part 25),
but also with the transport airworthiness requirements of the countries
to which the airplane is to be exported.
The European countries have developed a common airworthiness code
for transport airplanes that is administered by the Joint Aviation
Authorities (JAA) of Europe. This code is the result of a European
effort to harmonize the various airworthiness codes of the European
countries and is called the Joint Aviation Requirements (JAR)-25. It
was developed in a format similar to part 25. Many other countries have
airworthiness codes that are aligned closely to part 25 or to JAR-25,
or they use these codes directly for their own certification purposes.
The Aviation Rulemaking Advisory Committee (ARAC) was established
by the FAA on February 15, 1991, with the purpose of providing
information, advice, and recommendations to be considered in rulemaking
activities. By notice in the Federal Register (59 FR 30081, June 10,
1994), the FAA assigned several new tasks to an ARAC working group of
industry and government structural loads specialists from Europe, the
United States, and Canada. Task 6 of the working group charter
concerned the shock absorption test requirements for landing gear. The
ARAC working group has completed its work for this task and the ARAC
has made recommendations to the FAA by letter dated October 29, 1997.
Although the requirements for landing gear shock absorption tests
are essentially the same between the Federal Aviation Regulations and
JAR, the requirements do not address the capabilities of modern
technology and
[[Page 32979]]
do not take into account other related changes in the requirements for
landing gear load conditions that have already been incorporated into
other sections of the Federal Aviation Regulations. When the landing
loads requirements for transport airplanes were originally developed,
they required the landing load factors to be determined and applied to
the airplane. The airplane was treated as a rigid body and the landing
loads were applied to this rigid representation of the airplane for the
purpose of structural analysis. For the early landing gear systems,
analysis alone was considered sufficient for determining the landing
load factor that would be applied to the rigid airplane. It was only
necessary to determine the landing load factor (by analysis or tests)
and this load factor would then be used to design and substantiate the
airplane for the landing load conditions.
The development of more complex landing gear systems, for which
analysis alone was unreliable, led to the adoption of a requirement to
verify the landing load factor by actual shock absorption tests. This
requirement was added to the Civil Air Regulations (CAR) part 4b, which
was the predecessor to part 25. These shock absorption tests were
allowed by Sec. 4b.200 of the CAR to be free drop tests in which the
gear alone, could be dropped in free fall to impact the ground. In
these tests, mass is added to represent the proportion of the airplane
weight on the landing gear unit, and the mass may be reduced to account
for the effects of airplane lift acting during the landing impact.
Later, the corresponding requirement in Sec. 25.723(a), was modified to
allow the substantiation of some changes to the landing gear shock
absorption systems by analysis alone without verification by tests.
Part 25 currently requires the landing loads to be determined by
accounting for the dynamic flexible airplane. In addition, the landing
gear shock absorption systems have become even more sophisticated. At
the same time, the ability to develop highly sophisticated computer
models of landing gear and airplane structures has also improved. In
order to determine the airplane loads from the landing load conditions,
it is no longer sufficient to determine just the load factor from a
drop test of a landing gear unit. A comprehensive analysis of the
combined dynamic systems for the landing gear and airplane are
essential in order to determine the structural design loads for the
airplane. In developing this dynamic model, it is necessary to provide
an accurate representation of all the landing gear dynamic
characteristics. This includes the energy absorption characteristics
and the time histories of force and displacement during a landing
impact. The current Secs. 25.473(d) and 25.723(a) for shock absorption
tests require just the determination of the limit landing load factor
from the drop test.
Discussion
The proposed revisions to Sec. Sec. 25.473(d) and 25.723(a) would
provide for the new objective of the landing gear energy absorption
tests which would be to validate the landing gear dynamic
characteristics rather than to directly determine landing gear load
factors. These revisions would require that these characteristics be
substantiated over the range of landing conditions and airplane
configurations expected in service. The manufacturer would be expected
to substantiate the landing gear dynamic characteristics over the full
range of weight conditions and configurations. As a minimum, the energy
absorption characteristics would be confirmed by an energy absorption
test at the weight condition for landing (maximum takeoff weight or
maximum landing weight) which provides the maximum impact energy. This
is in contrast to the current Sec. Sec. 25.473(d) and 25.723(a) which
specifically require energy absorption tests at both the maximum
landing weight condition and the maximum takeoff weight condition. The
proposed rule would continue to provide for the substantiation of minor
changes by analyses. To provide guidance in complying with the new
proposed rule, a new advisory circular, AC 25.723-1, Shock Absorption
Tests, is proposed.
The proposals for the revised Sec. Sec. 25.473(d) and 25.723(a)
take into account the potential for sophisticated computer simulations
that accurately represent the dynamic characteristics. These are also
consistent with improvements in the landing load requirements that
necessitate an accurate representation of the landing gear shock
absorption characteristics. These proposals also provide more
flexibility for the airplane manufacturer to determine the range of
conditions and configurations over which to validate the analytical
model for the landing conditions. The extent to which this analytical
model could be extrapolated to include future design changes would
depend on the range of conditions and configurations originally
selected by the manufacturer for validation of the model.
The current Sec. Sec. 25.725 and 25.727 are proposed to be deleted
as regulatory requirements and would be set forth in the new proposed
AC 25.723-1. These criteria would be modified to reflect the advisory
nature of the material as well as the revised objective of determining
landing gear dynamic characteristics instead of landing gear limit
inertia load factors. For the most part, these rules currently provide
acceptable means of conducting energy absorption tests by means of a
drop test. Section 25.725 provides an acceptable means of conducting a
limit drop test for compliance with Sec. 25.723(a), and Sec. 25.727
provides an acceptable means of conducting a reserve energy drop test
in compliance with Sec. 25.723(b). Most of the guidance is limited to a
``free'' drop test in which a reduced effective weight is used to
represent lift during the landing impact. The only item in these two
sections that is considered to be regulatory in nature is the current
Sec. 25.725(c) concerning the attitude of the landing gear and the
representation of drag loads during the tests. Therefore this paragraph
has been modified to apply to all types of landing gear energy
absorption tests (not just drop tests) and it is now set forth in
Sec. 25.723(a)(2) of the proposed rule. It is expected that these
revisions will have no effect on the level of safety provided by the
requirement.
Paperwork Reduction Act
In accordance with the Paperwork Reduction Act of 1995 (44 U.S.C.
3507(d)), there are no requirements for information collection
associated with this proposed rule.
International Compatibility
The FAA has reviewed corresponding International Civil Aviation
Organization international standards and recommended practices and
Joint Aviation Authorities regulations, where they exist, and has
identified no differences in these proposed amendments and the foreign
regulations.
Regulatory Evaluation Summary
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
Office of Management and Budget directs agencies to assess the effect
of regulatory changes on international trade. In conducting these
analyses, the FAA has determined that this proposed
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rule is not ``a significant regulatory action'' under section 3(f) of
Executive Order 12866 and, therefore, is not subject to review by the
Office of Management and Budget. This proposed rule is not considered
significant under the regulatory policies and procedures of the
Department of Transportation (44 FR 11034, February 26, 1979). This
proposed rule would not have a significant impact on a substantial
number of small entities and would not constitute a barrier to
international trade. The FAA invites the public to provide comments and
supporting data on the assumptions made in this evaluation. All
comments received will be considered in the final regulatory
evaluation.
The proposed requirements, applicable to future type certificated
transport category airplanes, would result in two regulatory changes:
(1) Utilizing landing gear energy absorption tests to validate the
landing gear dynamic characteristics rather than the limit load factor
value, and (2) confirming energy absorption characteristics by
requiring tests at either the maximum landing weight or maximum takeoff
weight condition, whichever provides the maximum landing impact energy.
This is in contrast to current requirements which require tests at both
weight conditions.
The test results would be used to develop the analytical modeling
of the landing gear dynamic characteristics. These regulatory changes
would not result in any physical change in the way landing gears are
tested: the attitude of the gear being usually simulated directly by
orienting the gear on the rig and drag loads being applied by spinning
the wheel up to the ground speed. Therefore, it would not impose
additional costs on manufacturers. This was confirmed by two
manufacturers.
Significant cost savings may result from not having to test both at
maximum landing weight and maximum takeoff weight, but instead,
conducting shock absorption tests only for the conditions associated
with maximum energy. One manufacturer estimates that these tests would
result in 15 fewer test conditions per airplane certification. At a
cost of $5,000 per condition, the total cost savings would reach
$75,000 per airplane certification. Another manufacturer estimates a
cost savings of approximately $190,000 for a ten-year period.
Additionally, by harmonizing the standards of the Federal Aviation
Regulations and JAR, the proposed rule would yield cost savings by
eliminating duplicate certification activities.
Based on the finding of regulatory cost-savings, coupled with the
cost-savings realizable from harmonization, and the expectation that
these revisions will have no effect on the level of safety provided by
the test requirements, the FAA has determined that the proposed rule
would be cost-beneficial.
Initial Regulatory Flexibility Determination
The Regulatory Flexibility Act of 1980 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,
organization, and governmental jurisdictions subject to regulation.''
To achieve that principal, 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 (RFA) as
described in the Act. However, if an agency determines that a proposed
or final rule is not expected to have a significant economic impact on
a substantial number of small entities, section 605(b) of the 1980 act
provides that the head of the agency may so certify and an RFA is not
required. The certification must include a statement providing the
factual basis for this determination, and the reasoning should be
clear.
The proposed rule would affect manufacturers of transport category
airplanes produced under future new airplane type certifications. For
manufacturers, a small entity has 1,500 or fewer employees. Since no
part 25 airplane manufacturer has 1,500 or fewer employees, FAA
certifies that the proposed rule will not have a significant economic
impact on a substantial number of small entities.
International Trade Impact Statement
The provisions of this proposed rule would have no adverse impact
on trade for both U.S. firms doing business in foreign countries and
foreign firms doing business in the United States. By making U.S.
landing gear test requirements conform with JAR requirements,
international trade in aircraft would be enhanced by eliminating
redundant testing costs for part 25 airplane manufacturers, possibly
resulting in some cost savings for users of aircraft.
Federalism Implications
The regulations proposed herein would 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. Thus, in
accordance with Executive Order 12612, it is determined that this
proposal does not have sufficient federalism implications to warrant
the preparation of a federalism assessment.
Unfunded Mandates Reform Act
Title II of the Unfunded Mandates Reform Act of 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. 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 would 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.
This proposed rule does not contain a Federal intergovernmental or
private sector mandate that exceeds $100 million a year.
Regulations Affecting Interstate Aviation in Alaska
Section 1205 of the FAA Reauthorization Act of 1996 (110 Stat.
3213) requires the Administrator, when
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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.
Environmental Analysis
Federal Aviation Administration Order 1050.1D defines FAA actions
that may be categorically excluded from preparation of a National
Environmental Policy Act (NEPA) environmental assessment or
environmental impact statement. In accordance with FAA Order 1050.1D,
appendix 4, paragraph 4(j), this rulemaking, which if implemented may
cause a significant impact on the human environment, qualifies for a
categorical exclusion.
Energy Impact
The energy impact of the proposed rule has been assessed in
accordance with the Energy Policy and Conservation Act (EPCA) and
Public Law 94-163, as amended (42 U.S.C. 6362). It has been determined
that it is not a major regulatory action under the provisions of the
EPCA.
List of Subjects 14 CFR Part 25
Aircraft, Aviation safety, Reporting and recordkeeping
requirements.
The Proposed Amendments
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 and 44704.
2. Section 25.473 is amended by revising paragraph (d) to read as
follows:
Sec. 25.473 Landing load conditions and assumptions.
* * * * *
(d) The landing gear dynamic characteristics must be validated by
tests as defined in Sec. 25.723(a).
* * * * *
3. Section 25.723 is amended by revising paragraph (a) to read as
follows:
Sec. 25.723 Shock absorption tests.
(a) Except as provided in paragraph (a)(3) of this section, the
landing gear dynamic characteristics used for design must be validated
by energy absorption tests. The dynamic characteristics must be
substantiated for the range of landing conditions, airplane
configurations, and service variations expected in operation.
(1) The configurations subjected to energy absorption tests must
include at least the maximum landing weight or the maximum takeoff
weight, whichever produces the greater value of landing impact energy.
(2) The test attitude of the landing gear unit and the application
of appropriate drag loads during the test must simulate the airplane
landing conditions in a manner consistent with the development of
rational or conservative limit loads.
(3) Changes in previously approved design weights and minor changes
in design may be substantiated by analyses based on previous tests
conducted on the same basic landing gear system that has similar energy
absorption characteristics.
* * * * *
Sec. 25.725 [Removed and Reserved]
4. Remove and reserve Sec. 25.725.
Sec. 25.727 [Removed and Reserved]
5. Remove and reserve Sec. 25.727.
* * * * *
Issued in Washington D.C. on June 10, 1999.
Frank Paskiewicz,
Acting Director, Aircraft Certification Service.
[FR Doc. 99-15381 Filed 6-17-99; 8:45 am]
BILLING CODE 4910-13-U
