Special Conditions: Airbus Model A380-800 Airplane, Loading Conditions for Multi-Leg Landing Gear, 15345-15350 [06-2973]
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Federal Register / Vol. 71, No. 59 / Tuesday, March 28, 2006 / Proposed Rules
12 CFR Part 614
Agriculture, Banks, banking, Foreign
trade, Reporting and recordkeeping
requirements, Rural areas.
For the reasons stated in the
preamble, parts 611, 612, 613 and 614
of chapter VI, title 12 of the Code of
Federal Regulations are proposed to be
amended as follows:
PART 611—ORGANIZATION
1. The authority citation for part 611
continues to read as follows:
Authority: Secs. 1.3, 1.4, 1.13, 2.0, 2.1,
2.10, 2.11, 3.0, 3.2, 3.21, 4.12, 4.15, 4.20,
4.21, 5.9, 5.10, 5.17, 6.9, 6.26, 7.0–7.13, 8.5(e)
of the Farm Credit Act (12 U.S.C. 2011, 2013,
2021, 2071, 2072, 2091, 2092, 2121, 2123,
2142, 2183, 2203, 2208, 2209, 2243, 2244,
2252, 2278a–9, 2278b–6, 2279a–2279f–1,
2279aa–5(e)); secs. 411 and 412 of Pub. L.
100–233, 101 Stat. 1568, 1638; secs. 409 and
414 of Pub. L. 100–399, 102 Stat. 989, 1003,
and 1004.
§ 611.1135 Incorporation of service
corporations.
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(b) Who may own equities in your
service corporation?
(1) Your service corporation may only
issue voting and non-voting stock to:
(i) One or more Farm Credit banks
and associations; and
(ii) Persons that are not Farm Credit
banks or associations, provided that at
least 80 percent of the voting stock is at
all times held by Farm Credit banks or
associations.
(2) For the purposes of this subpart,
we define persons as individuals or
legal entities organized under the laws
of the United States or any state or
territory thereof.
*
*
*
*
*
PART 612—STANDARDS OF
CONDUCT AND REFERRAL OF
KNOWN OR SUSPECTED CRIMINAL
VIOLATIONS
dsatterwhite on PROD1PC76 with PROPOSALS
Authority: Secs. 5.9, 5.17, 5.19 of the Farm
Credit Act (12 U.S.C. 2243, 2252, 2254).
Subpart A—Standards of Conduct
4. Amend 612.2155 by revising
paragraph (d) to read as follows:
Employee reporting.
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*
(d) A newly hired employee shall
report matters required to be reported in
15:43 Mar 27, 2006
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Authority: Secs. 1.5, 1.7, 1.9, 1.10, 1.11,
2.2, 2.4, 2.12, 3.1, 3.7, 3.8, 3.22, 4.18A, 4.25,
4.26, 4.27, 5.9, 5.17 of the Farm Credit Act
(12 U.S.C. 2013, 2015, 2017, 2018, 2019,
2073, 2075, 2093, 2122, 2128, 2129, 2143,
2206a, 2211, 2212, 2213, 2243, 2252).
Subpart B—Financing for Banks
Operating Under Title III of the Farm
Credit Act
6. Amend § 613.3100 by revising
paragraphs (b)(1)(iii)(B) and (d)(1) to
read as follows:
Domestic lending.
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(b) * * *
(1) * * *
(iii) * * *
(B) The cooperative restricts
dividends on stock or membership
capital to the maximum percentage per
year permitted by applicable state law.
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(d) Water and waste disposal
facilities.
(1) Eligibility. A cooperative or a
public agency, quasi public agency,
body, or other public or private entity
that, under the authority of state or local
law, establishes and operates water and
waste disposal facilities in a rural area,
as that term is defined by paragraph
(a)(4) of this section, is eligible to
borrow from a bank for cooperatives or
an agricultural credit bank.
*
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PART 614—LOAN POLICIES AND
OPERATIONS
7. The authority citation for part 614
continues to read as follows:
3. The authority citation for part 612
continues to read as follows:
VerDate Aug<31>2005
5. The authority citation for part 613
continues to read as follows:
*
2. Amend § 611.1135 by revising
paragraph (b) to read as follows:
*
PART 613—ELIGIBILITY AND SCOPE
OF FINANCING
§ 613.3100
Subpart I—Service Organizations
§ 612.2155
paragraphs (a), (b), and (c) of this
section to the Standards of Conduct
Official 5 business days after starting
employment and thereafter shall comply
with the requirements of this section.
Authority: 42 U.S.C. 4012a, 4104a, 4104b,
4106, and 4128; secs. 1.3, 1.5, 1.6, 1.7, 1.9,
1.10, 1.11, 2.0, 2.2, 2.3, 2.4, 2.10, 2.12, 2.13,
2.15, 3.0, 3.1, 3.3, 3.7, 3.8, 3.10, 3.20, 3.28,
4.12, 4.12A, 4.13B, 4.14, 4.14A, 4.14C, 4.14D,
4.14E, 4.18, 4.18A, 4.19, 4.25, 4.26, 4.27,
4.28, 4.36, 4.37, 5.9, 5.10, 5.17, 7.0, 7.2, 7.6,
7.8, 7.12, 7.13, 8.0, 8.5 of the Farm Credit Act
(12 U.S.C. 2011, 2013, 2014, 2015, 2017,
2018, 2019, 2071, 2073, 2074, 2075, 2091,
2093, 2094, 2097, 2121, 2122, 2124, 2128,
2129, 2131, 2141, 2149, 2183, 2184, 2201,
2202, 2202a, 2202c, 2202d, 2202e, 2206,
2206a, 2207, 2211, 2212, 2213, 2214, 2219a,
2219b, 2243, 2244, 2252, 2279a, 2279a–2,
2279b, 2279c–1, 2279f, 2279f–1, 2279aa,
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15345
2279aa–5); sec. 413 of Pub. L. 100–233, 101
Stat. 1568, 1639.
Subpart A—Lending Authorities
8. Amend § 614.4010 by revising
paragraphs (d)(1) and (d)(2) to read as
follows:
§ 614.4010
Agricultural credit banks.
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(d) * * *
(1) Eligible cooperatives, as defined in
§ 613.3100(b)(1), in accordance with
§§ 614.4200, 614.4231, 614.4232,
614.4233, and subpart Q of part 614;
(2) Other eligible entities, as defined
in § 613.3100(b)(2), in accordance with
§§ 614.4200, 614.4231, and 614.4232;
*
*
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*
Subpart F—Collateral Evaluation
Requirements
§ 614.4265
[Amended]
9. Amend § 614.4265 by removing
paragraph (c) and redesignating
paragraphs (d), (e), (f), (g), and (h) as (c),
(d), (e), (f), and (g), respectively.
Subpart Q—Banks for Cooperatives
and Agricultural Credit Banks
Financing International Trade
§ 614.4710
[Removed and reserved]
10. Remove and reserve § 614.4710.
Dated: March 23, 2006.
Roland E. Smith,
Secretary, Farm Credit Administration Board.
[FR Doc. E6–4479 Filed 3–27–06; 8:45 am]
BILLING CODE 6705–01–P
DEPARTMENT OF TRANSPORTATION
Federal Aviation Administration
14 CFR Part 25
[Docket No. NM341; Notice No. 25–06–02–
SC]
Special Conditions: Airbus Model
A380–800 Airplane, Loading
Conditions for Multi-Leg Landing Gear
Federal Aviation
Administration (FAA), DOT.
ACTION: Notice of proposed special
conditions.
AGENCY:
SUMMARY: This notice proposes special
conditions for the Airbus A380–800
airplane. This airplane will have novel
or unusual design features when
compared to the state of technology
envisioned in the airworthiness
standards for transport category
airplanes. Many of these novel or
unusual design features are associated
with the complex systems and the
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Federal Register / Vol. 71, No. 59 / Tuesday, March 28, 2006 / Proposed Rules
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configuration of the airplane, including
its full-length double deck. For these
design features, the applicable
airworthiness regulations do not contain
adequate or appropriate safety standards
regarding loading conditions for multileg landing gear. These proposed special
conditions contain the additional safety
standards that the Administrator
considers necessary to establish a level
of safety equivalent to that established
by the existing airworthiness standards.
Additional special conditions will be
issued for other novel or unusual design
features of the Airbus Model A380–800
airplane.
DATES: Comments must be received on
or before May 12, 2006.
ADDRESSES: Comments on this proposal
may be mailed in duplicate to: Federal
Aviation Administration, Transport
Airplane Directorate, Attention: Rules
Docket (ANM–113), Docket No. NM341,
1601 Lind Avenue, SW., Renton,
Washington 98055–4056; or delivered in
duplicate to the Transport Airplane
Directorate at the above address. All
comments must be marked: Docket No.
NM341. Comments may be inspected in
the Rules Docket weekdays, except
Federal holidays, between 7:30 a.m. and
4 p.m.
FOR FURTHER INFORMATION CONTACT:
Holly Thorson, FAA, International
Branch, ANM–116, Transport Airplane
Directorate, Aircraft Certification
Service, 1601 Lind Avenue, SW.,
Renton, Washington 98055–4056;
telephone (425) 227–1357; facsimile
(425) 227–1149.
SUPPLEMENTARY INFORMATION:
Comments Invited
The FAA invites interested persons to
participate in this rulemaking by
submitting written comments, data, or
views. The most helpful comments
reference a specific portion of the
special conditions, explain the reason
for any recommended change, and
include supporting data. We ask that
you send us two copies of written
comments.
We will file in the docket all
comments we receive as well as a report
summarizing each substantive public
contact with FAA personnel concerning
these proposed special conditions. The
docket is available for public inspection
before and after the comment closing
date. If you wish to review the docket
in person, go to the address in the
ADDRESSES section of this notice
between 7:30 a.m. and 4 p.m., Monday
through Friday, except Federal holidays.
We will consider all comments we
receive on or before the closing date for
comments. We will consider comments
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filed late, if it is possible to do so
without incurring expense or delay. We
may change the proposed special
conditions in light of the comments we
receive.
If you want the FAA to acknowledge
receipt of your comments on this
proposal, include with your comments
a pre-addressed, stamped postcard on
which the docket number appears. We
will stamp the date on the postcard and
mail it back to you.
Background
Airbus applied for FAA certification/
validation of the provisionallydesignated Model A3XX–100 in its
letter AI/L 810.0223/98, dated August
12, 1998, to the FAA. Application for
certification by the Joint Aviation
Authorities (JAA) of Europe had been
made on January 16, 1998, reference AI/
L 810.0019/98. In its letter to the FAA,
Airbus requested an extension to the 5year period for type certification in
accordance with 14 CFR 21.17(c). The
request was for an extension to a 7-year
period, using the date of the initial
application letter to the JAA as the
reference date. The reason given by
Airbus for the request for extension is
related to the technical challenges,
complexity, and the number of new and
novel features on the airplane. On
November 12, 1998, the Manager,
Aircraft Engineering Division, AIR–100,
granted Airbus’ request for the 7-year
period, based on the date of application
to the JAA.
In its letter AI/LE–A 828.0040/99
Issue 3, dated July 20, 2001, Airbus
stated that its target date for type
certification of the Model A380–800 had
been moved from May 2005, to January
2006, to match the delivery date of the
first production airplane. In a
subsequent letter (AI/L 810.0223/98
Issue 3, dated January 27, 2006), Airbus
stated that its target date for type
certification is October 2, 2006. In
accordance with 14 CFR 21.17(d)(2),
Airbus chose a new application date of
December 20, 1999, and requested that
the 7-year certification period which
had already been approved be
continued. The FAA has reviewed the
part 25 certification basis for the Model
A380–800 airplane, and no changes are
required based on the new application
date.
The Model A380–800 airplane will be
an all-new, four-engine jet transport
airplane with a full double-deck, twoaisle cabin. The maximum takeoff
weight will be 1.235 million pounds
with a typical three-class layout of 555
passengers.
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Type Certification Basis
Under the provisions of 14 CFR 21.17,
Airbus must show that the Model A380–
800 airplane meets the applicable
provisions of 14 CFR part 25, as
amended by Amendments 25–1 through
25–98. If the Administrator finds that
the applicable airworthiness regulations
do not contain adequate or appropriate
safety standards for the Airbus A380–
800 airplane because of novel or
unusual design features, special
conditions are prescribed under the
provisions of 14 CFR 21.16.
In addition to the applicable
airworthiness regulations and special
conditions, the Airbus Model A380–800
airplane must comply with the fuel vent
and exhaust emission requirements of
14 CFR part 34 and the noise
certification requirements of 14 CFR
part 36. In addition, the FAA must issue
a finding of regulatory adequacy
pursuant to section 611 of Public Law
93–574, the ‘‘Noise Control Act of
1972.’’
Special conditions, as defined in 14
CFR 11.19, are issued in accordance
with 14 CFR 11.38 and become part of
the type certification basis in
accordance with 14 CFR 21.17(a)(2).
Special conditions are initially
applicable to the model for which they
are issued. Should the type certificate
for that model be amended later to
include any other model that
incorporates the same novel or unusual
design feature, the special conditions
would also apply to the other model
under the provisions of 14 CFR 21.101.
Discussion of Novel or Unusual Design
Features
The A380 has a multi-leg landing gear
arrangement consisting of a nose gear,
two wing mounted gear, and two body
mounted gear. This arrangement is
different from the simpler, conventional
landing gear arrangement envisioned by
the landing and ground load
requirements of 14 CFR part 25. Those
regulations assume a landing gear
arrangement comprising a three point
suspension system (two main gear and
a nose or tail gear) in which load
sharing between the landing gear can be
determined without considering the
flexibility of the airframe. In fact,
§ 25.477 states that certain Ground Load
provisions apply only to ‘‘airplanes with
conventional arrangements of main and
nose gears, or main and tail gears, when
normal operating techniques are used.’’
For a five point suspension system,
like that of the A380, load sharing
between landing gear must be
determined in a rational manner
considering the flexibility of the
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airplane. Therefore, the landing and
ground load requirements of 14 CFR
part 25 are not valid, and special
conditions specifying the load
conditions appropriate to the multi-leg
landing gear on the A380 are necessary.
Proposed regulatory changes
pertaining to landing and ground
handling structural design loads have
been developed by a working group of
the Aviation Rulemaking and Advisory
Committee (ARAC). The proposal, dated
May 30, 2003, provides design load
requirements for various landing gear
configurations, including the multi-leg
landing gear configuration of the A380.
The special conditions proposed in
this document are based upon the
regulatory changes proposed by the
ARAC working group, as are the special
conditions issued by the European
Aviation Safety Agency for its
certification of the A380. For ease of
reference, the special conditions
proposed in this document are
organized in the same manner as in the
ARAC recommendation. Since the
changes proposed by ARAC cover
various landing gear configurations,
certain paragraphs of the proposal are
not applicable to the A380. These
paragraphs are so indicated in the
section of this notice, entitled ‘‘The
Proposed Special Conditions.’’
This notice contains two groups of
proposed special conditions. The first
group (Group A) addresses Landing
Conditions and includes proposed
special conditions pertaining to the
following:
A.1. Landing load conditions and
assumptions,
A.2. Symmetric landing load conditions,
A.3. One-gear landing conditions, and
A.4. Side load conditions.
The second group (Group B)
addresses other conditions and tests,
including Ground Handling Conditions.
It includes proposed special conditions
pertaining to the following:
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B.1. Ground handling conditions,
B.2. Taxi, takeoff and landing roll,
B.3. Braked roll conditions,
B.4. Nose-wheel yaw and steering,
B.5. Pivoting,
B.6. Reversed braking,
B.7. Ground load: unsymmetrical loads on
multiple-wheel units, and
B.8. Shock absorption tests.
Applicability
As discussed above, these special
conditions are applicable to the Airbus
A380–800 airplane. Should Airbus
apply at a later date for a change to the
type certificate to include another
model incorporating the same novel or
unusual design features, these special
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15347
conditions would apply to that model as
well under the provisions of § 21.101.
However, this coefficient of friction
need not be more than 0.8.
Conclusion
2. Symmetric Landing Load Conditions
This action affects only certain novel
or unusual design features of the Airbus
A380–800 airplane. It is not a rule of
general applicability.
In lieu of §§ 25.479 and 25.481, the
following special conditions apply:
The landing gear and airframe
structure must be designed for the
dynamic landing conditions of Special
Condition A.2., using the assumptions
specified in Special Condition A.1.
(a) The airplane is assumed to contact
the ground—
(1) With an airspeed corresponding to
the attitudes specified in paragraph (c)
of this special condition in the
following conditions: (i) Standard sea
level conditions, and (ii) at maximum
approved altitude in a hot day
temperature of 22.8°C (41°F) above
standard.
The airspeed need not be greater than
1.25VS0, or less than VS0, where VS0 =
the 1-g stalling speed based on CNAmax
at the appropriate weight and in the
landing configuration. The effects of
increased ground contact speeds must
be investigated to account for
downwind landings for which approval
is desired.
(2) With a limit descent velocity of
3.05 m/sec (10 fps) at the design landing
weight (the maximum weight for
landing conditions at maximum descent
velocity); and,
(3) With a limit descent velocity of
1.83 m/sec (6 fps) at the design takeoff
weight (the maximum weight for
landing conditions at a reduced descent
velocity).
(b) Not applicable to A380.
(c) For airplanes with nose wheels,
the conditions specified in this
paragraph must be investigated
assuming the following attitudes:
(1) An attitude in which the nose and
main wheels are assumed to contact the
ground simultaneously, as shown in 14
CFR part 25, Appendix A, Figure 2. For
this condition, airplane pitching
moment is assumed to be reacted by the
nose gear.
(2) An attitude corresponding to the
smallest pitch attitude at which the
main landing gear reach maximum
vertical compression before impact on
the nose gear.
(3) An attitude corresponding to
either the stalling angle or the maximum
angle allowing clearance with the
ground by each part of the airplane
other than any wheel of the main
landing gear, in accordance with 14 CFR
part 25, Appendix A, Figure 3,
whichever is less.
(4) For aircraft with more than two
main landing gear or more than two
wheels per main landing gear unit, each
List of Subjects in 14 CFR Part 25
Aircraft, Aviation safety, Reporting
and recordkeeping requirements.
The authority citation for these
special conditions is as follows:
Authority: 49 U.S.C. 106(g), 40113, 44701,
44702, 44704.
The Proposed Special Conditions
Accordingly, pursuant to the
authority delegated to me by the
Administrator, the Federal Aviation
Administration (FAA) proposes the
following special conditions as part of
the type certification basis for the
Airbus A380–800 airplane.
A. Landing Conditions
1. Landing Load Conditions and
Assumptions
In lieu of §§ 25.473 and 25.477, the
following special conditions apply:
(a) The landing gear and airplane
structure must be investigated for the
landing conditions specified in Special
Conditions A.2., A.3., and A.4. For these
conditions, the airplane is assumed to
contact the ground—
(1) In the attitudes defined in Special
Conditions A.2. and A.3.
(2) At the descent velocities defined
in Special Conditions A.2. and A.3. The
prescribed descent velocities may be
modified, if it is shown that the airplane
has design features that make it
impossible to develop these velocities.
(b) Airplane lift, not exceeding
airplane weight, may be assumed,
unless the presence of systems or
procedures significantly affects the lift.
(c) The method of analysis of airplane
and landing gear loads must take into
account at least the following elements:
(1) Landing gear dynamic
characteristics.
(2) Spin-up and spring back.
(3) Rigid body response.
(4) Structural dynamic response of the
airframe, if significant.
(5) Each approved tire with nominal
characteristics.
(d) The landing gear dynamic
characteristics must be validated by
tests as defined in Special Condition
B.8., paragraph (a).
(e) The coefficient of friction between
the tires and the ground may be
established by considering the effects of
skidding velocity and tire pressure.
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intermediate attitude that may be
critical.
(d) For airplanes with more than two
main landing gear, landing must be
considered on a level runway and, as a
separate condition, on a runway having
a convex upward shape that may be
approximated by a slope of 1.5% at
main landing gear stations.
3. One-Gear Landing Conditions
In lieu of § 25.483, the following
special condition applies:
(a) Not applicable to the A380.
(b) For airplanes with more than two
main landing gear, a dynamic rolled
landing condition on a level runway
must be considered, using the
assumptions specified in Special
Condition A.1., in which—
(1) The airplane is assumed to contact
the ground—
(i) At the maximum roll angle
attainable within the geometric
limitations of the airplane; (however,
the roll angle need not exceed 10
degrees),
(ii) With a limit descent velocity of
2.13 m/sec (7 fps) at the design landing
weight,
(iii) At the critical pitch attitudes and
corresponding contact velocities
obtained under Special Conditions No.
A.2.
(2) The dynamic analysis must
include the contact of all gear outboard
of the airplane centerline on the side of
first gear impact. This condition need
not apply to the gear on the opposite
side of the airplane.
(3) Side loads (in the ground reference
system) may be assumed to be zero.
(4) Airplane rolling moments shall be
reacted by airplane inertia forces and by
subsequent main gear reactions.
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4. Side Load Conditions
In lieu of § 25.485, the following
special conditions apply:
For the side load conditions specified
in paragraphs (a) and (b) below, the
vertical and drag loads are assumed to
act at the wheel axle centerline, and the
side loads are assumed to act at the
ground contact point. The gear loads are
balanced by inertia of the airplane.
(a) The most severe combination of
loads that are likely to arise during a
lateral drift landing must be taken into
account. In the absence of a more
rational analysis of this condition, the
following must be investigated:
(1) A separate condition for each gear,
for which the vertical load is assumed
to be 75% of the maximum vertical
reaction obtained in Special Condition
A.2. or A.3., whichever is greater. For
airplanes with more than two main
landing gear, the vertical load on the
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other gear is assumed to be 75% of the
correlated vertical load for those gear in
the same condition. The vertical loads
for each gear are combined with drag
and side loads of 40% and 25%,
respectively, of the vertical load.
(2) The airplane is assumed to be in
the attitude corresponding to the
maximum vertical reaction obtained in
Special Condition A.2 or A.3.,
whichever is greater.
(3) The shock absorber and tire
deflections must be assumed to be 75%
of the deflection corresponding to the
vertical loads obtained in Special
Condition A.2., whichever is greater.
(b) In addition to the side load
conditions specified in paragraph (a)
above, the following side load
conditions must be considered for each
main landing gear unit:
(1) A separate condition for each main
landing gear unit, for which the vertical
load is assumed to be 50% of the
maximum vertical reaction obtained in
Special Condition A.2. For airplanes
with more than two main gear, the
vertical load on other gear is assumed to
be 50% of the correlated vertical load
for those gear in the same condition.
The vertical loads for each gear are
combined with the side loads specified
in paragraph (b)(3) or (b)(4) of this
special condition, as applicable.
(2) The airplane is assumed to be in
the attitude corresponding to the
maximum vertical reaction obtained in
Special Conditions A.2.
(3) For the outboard main landing
gear, side loads of 0.8 of the vertical
reaction (on one side) acting inward and
0.6 of the vertical reaction (on the other
side) acting outward as shown in 14
CFR part 25, Appendix A, Figure 5.
(4) For airplanes with more than two
main landing gear, the side load of each
inboard main landing gear is
determined by a linear interpolation
between 0.8 and 0.6 of the vertical gear
load on that gear, depending on the
lateral position of that gear relative to
the outboard main landing gear. The
side loads act in the same direction as
the outboard main gear side loads.
(5) The drag loads may be assumed to
be zero.
(6) The shock absorber and tire
deflections must be assumed to be 50%
of the deflection corresponding to the
vertical loads of Special Conditions A.2.
B. Ground Handling Conditions
1. Ground Handling Conditions
In lieu of § 25.489, the following
special conditions apply:
(a) Unless otherwise prescribed, the
landing gear and airplane structure must
be investigated for the conditions in
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§ 25.509 and in Special Conditions. B.2,
B.3, B.4, B.5, and B.6, as follows:
(1) The airplane must be assumed to
be at the design ramp weight (the
maximum weight for ground handling
conditions);
(2) The airplane lift must be assumed
to be zero; and
(3) The shock absorbers and tires may
be assumed to be in their static position.
(b) For airplanes with more than two
main landing gears, the airplane must be
considered to be on a level runway and,
as a separate condition, on a runway
having a convex upward shape that may
be approximated by a slope of 1.5% at
the main landing gear stations. The
ground reactions must be distributed to
the individual landing gear in a rational
or conservative manner.
2. Taxi, Takeoff and Landing Roll
In lieu of § 25.491, the following
special condition applies:
Within the range of appropriate
ground speeds and approved weights,
the airplane structure and landing gear
are assumed to be subjected to loads not
less than those obtained when the
aircraft is operating over the roughest
ground that may reasonably be expected
in normal operation. Steady
aerodynamic effects must be considered
in a rational or conservative manner.
3. Braked Roll Conditions
In lieu of § 25.493, the following
special conditions apply:
(a) Not applicable to A380.
(b)For an airplane with a nose wheel,
the limit vertical load factor is 1.2 at the
design landing weight and 1.0 at the
design ramp weight. A drag reaction
equal to the vertical reaction, multiplied
by a coefficient of friction of 0.8, must
be combined with the vertical reaction
and applied at the ground contact point
of each wheel with brakes. The
following two attitudes, in accordance
with14 CFR part 25, Appendix A, Figure
6, must be considered:
(1) The level attitude with the wheels
contacting the ground and the loads
distributed between the main and nose
gear. Zero pitching acceleration is
assumed.
(2) The level attitude with only the
main gear contacting the ground and
with the pitching moment resisted by
angular acceleration.
(c) 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
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dsatterwhite on PROD1PC76 with PROPOSALS
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 (e) of
this paragraph.
(d) Not applicable to the A380.
(e) A drag reaction lower than that
prescribed in Special Condition B.3 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.
4. Nose-Wheel Yaw and Steering
In lieu of § 25.499, the following
special conditions apply:
(a) A vertical load factor of 1.0 at the
airplane center of gravity and a side
component at the nose wheel ground
contact equal to 0.8 of the vertical
ground reaction at that point are
assumed.
(b) With the airplane assumed to be in
static equilibrium with the loads
resulting from the use of brakes on one
side of the main landing gear system,
the nose gear, its attaching structure,
and the fuselage structure forward of the
center of gravity must be designed for
the following loads:
(1) A vertical load factor at the center
of gravity of 1.0.
(2) For wheels with brakes applied,
the coefficient of friction must be 0.8.
Drag loads are balanced by airplane
inertia. Airplane pitching moment is
reacted by the nose gear.
(3) Side and vertical loads at the
ground contact point on the nose gear
that are required for static equilibrium.
(4) A side load factor at the airplane
center of gravity of zero.
(c) If the loads prescribed in
paragraph (b) above result in a nose gear
side load higher than 0.8 times the
vertical nose gear load, the design nose
gear side load may be limited to 0.8
times the vertical load, with unbalanced
yawing moments assumed to be resisted
by airplane inertia forces.
(d) For other than the nose gear, its
attaching structure, and the forward
fuselage structure, the loading
conditions are those prescribed in
paragraph (b) above, except that—
(1) A lower drag reaction may be used
if an effective drag force of 0.8 times the
vertical reaction cannot be reached
under any likely loading condition; and
(2) The forward acting load at the
center of gravity need not exceed the
maximum drag reaction on the main
landing gear, determined in accordance
with Special Conditions B.3., paragraph
(b).
(e) With the airplane at design ramp
weight, and the nose gear in any
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Jkt 208001
steerable position, the combined
application of full normal steering
torque and vertical force equal to 1.33
times the maximum static reaction on
the nose gear must be considered in
designing the nose gear, its attaching
structure, and the forward fuselage
structure.
5. Pivoting
In lieu of § 25.503, the following
special condition applies:
The main landing gear and supporting
structure must be designed for the loads
induced by pivoting during ground
maneuvers in paragraph (b) below.
(a) Not applicable to A380.
(b) For airplanes with more than two
main landing gear, the following
pivoting conditions must be considered:
(1) The following rational pivoting
maneuvers must be considered:
(i) Towing at the nose gear at the
critical towing angle, no brakes applied,
and separately,
(ii) Application of symmetrical and
unsymmetrical forward thrust to aid
pivoting, with and without braking by
pilot action on the pedals.
(2) The airplane is assumed to be in
static equilibrium, with the loads being
applied at the ground contact points.
(3) The limit vertical load factor must
be 1.0, and
(i) For wheels with brakes applied,
the coefficient of friction must be 0.8.
(ii) For wheels with brakes not
applied, the ground tire reactions must
be based on reliable tire data.
6. Reversed Braking
In lieu of § 25.507, the following
special conditions apply:
(a) The airplane must be in a static
ground attitude. Horizontal reactions
parallel to the ground and directed
forward must be applied at the ground
contact point of each wheel with brakes.
The limit loads must be equal to 0.55
times the vertical load at each wheel or
to the load developed by 1.2 times the
nominal maximum static brake torque,
whichever is less.
(b) For airplanes with nose gears, the
pitching moment must be balanced by
rotational inertia.
7. Ground Load: Unsymmetrical Loads
on Multiple-Wheel Units
In lieu of § 25.511, subparagraphs (d)
and (e), the following special conditions
apply:
(a) Landing conditions. For one and
for two deflated tires, the applied load
to each gear unit is assumed to be 60
percent and 50 percent, respectively, of
the limit load applied to each gear for
each of the prescribed landing
conditions. However, for Special
PO 00000
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Fmt 4702
Sfmt 4702
15349
Condition A.4., paragraph (b), 100
percent of the vertical load must be
applied. Special Condition A.4.,
paragraph (a)(3), need not be considered
with deflated tires.
(b) Taxiing and ground handling
conditions. For one and for two deflated
tires—
(1) The applied side or drag load
factor, or both factors, at the center of
gravity must be the most critical value
up to 50 percent and 40 percent,
respectively, of the limit side or drag
load factors, or both factors,
corresponding to the most severe
condition resulting from consideration
of the prescribed taxiing and ground
handling conditions;
(2) For the braked roll conditions of
Special Conditions B.3., paragraph
(b)(2), the drag loads on each inflated
tire may not be less than those at each
tire for the symmetrical load
distribution with no deflated tires;
(3) The vertical load factor at the
center of gravity must be 60 percent and
50 percent, respectively, of the factor
with no deflated tires, except that it may
not be less than 1g; and
(4) The pivoting condition of Special
Condition B.5. and the braked roll
conditions of Special Condition B.3.,
paragraph (c), need not be considered
with deflated tires.
8. Shock Absorption Tests
In lieu of § 25.723, the following
special conditions apply:
(a) The analytical representation of
the landing gear dynamic characteristics
that is used in determining the landing
loads must be validated by energy
absorption tests. A range of tests must
be conducted to ensure that the
analytical representation is valid for the
design conditions specified in Special
Conditions A.2. and A.3., if applicable.
(1) The configurations subjected to
energy absorption tests at limit design
conditions must include both the
condition with the maximum energy
absorbed by the landing gear and the
condition with the maximum descent
velocity obtained from Special
Condition A.2. and A.3.
(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.
(b) Each landing gear unit may not fail
in a test, demonstrating its reserve
energy absorption capacity, assuming—
(3) The test descent velocity is 120%
of that corresponding to the condition
specified in paragraph (b)(1) of this
paragraph;
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Federal Register / Vol. 71, No. 59 / Tuesday, March 28, 2006 / Proposed Rules
(4) The effects of wheel spin-up need
not be included.
(c) In lieu of the tests prescribed in
this paragraph, 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.
Issued in Renton, Washington, on March
20, 2006.
Ali Bahrami,
Manager, Transport Airplane Directorate,
Aircraft Certification Service.
[FR Doc. 06–2973 Filed 3–27–06; 8:45 am]
BILLING CODE 4910–13–P
1601 Lind Avenue SW., Renton,
Washington 98055–4056; or delivered in
duplicate to the Transport Airplane
Directorate at the above address. All
comments must be marked: Docket No.
NM343. Comments may be inspected in
the Rules Docket weekdays, except
Federal holidays, between 7:30 a.m. and
4 p.m.
FOR FURTHER INFORMATION CONTACT:
Holly Thorson, FAA, International
Branch, ANM–116, Transport Airplane
Directorate, Aircraft Certification
Service, 1601 Lind Avenue SW.,
Renton, Washington 98055–4056;
telephone (425) 227–1357; facsimile
(425) 227–1149.
SUPPLEMENTARY INFORMATION:
DEPARTMENT OF TRANSPORTATION
Federal Aviation Administration
14 CFR Part 25
[Docket No. NM343; Notice No. 25–06–04–
SC]
Special Conditions: Airbus Model
A380–800 Airplane, Airplane Jacking
Loads
Federal Aviation
Administration (FAA), DOT.
ACTION: Notice of proposed special
conditions.
dsatterwhite on PROD1PC76 with PROPOSALS
AGENCY:
SUMMARY: This notice proposes special
conditions for the Airbus A380–800
airplane. This airplane will have novel
or unusual design features when
compared to the state of technology
envisioned in the airworthiness
standards for transport category
airplanes. Many of these novel or
unusual design features are associated
with the complex systems and the
configuration of the airplane, including
its full-length double deck. For these
design features, the applicable
airworthiness regulations do not contain
adequate or appropriate safety standards
regarding airplane jacking loads. These
proposed special conditions contain the
additional safety standards that the
Administrator considers necessary to
establish a level of safety equivalent to
that established by the existing
airworthiness standards. Additional
special conditions will be issued for
other novel or unusual design features
of the Airbus Model A380–800 airplane.
DATES: Comments must be received on
or before May 12, 2006.
ADDRESSES: Comments on this proposal
may be mailed in duplicate to: Federal
Aviation Administration, Transport
Airplane Directorate, Attention: Rules
Docket (ANM–113), Docket No. NM343,
VerDate Aug<31>2005
15:43 Mar 27, 2006
Jkt 208001
Comments Invited
The FAA invites interested persons to
participate in this rulemaking by
submitting written comments, data, or
views. The most helpful comments
reference a specific portion of the
special conditions, explain the reason
for any recommended change, and
include supporting data. We ask that
you send us two copies of written
comments.
We will file in the docket all
comments we receive as well as a report
summarizing each substantive public
contact with FAA personnel concerning
these proposed special conditions. The
docket is available for public inspection
before and after the comment closing
date. If you wish to review the docket
in person, go to the address in the
ADDRESSES section of this notice
between 7:30 a.m. and 4 p.m., Monday
through Friday, except Federal holidays.
We will consider all comments we
receive on or before the closing date for
comments. We will consider comments
filed late, if it is possible to do so
without incurring expense or delay. We
may change the proposed special
conditions in light of the comments we
receive.
If you want the FAA to acknowledge
receipt of your comments on this
proposal, include with your comments
a pre-addressed, stamped postcard on
which the docket number appears. We
will stamp the date on the postcard and
mail it back to you.
Background
Airbus applied for FAA certification/
validation of the provisionallydesignated Model A3XX–100 in its
letter AI/L 810.0223/98, dated August
12, 1998, to the FAA. Application for
certification by the Joint Aviation
Authorities (JAA) of Europe had been
made on January 16, 1998, reference AI/
L 810.0019/98. In its letter to the FAA,
PO 00000
Frm 00011
Fmt 4702
Sfmt 4702
Airbus requested an extension to the 5year period for type certification in
accordance with 14 CFR 21.17(c). The
request was for an extension to a 7-year
period, using the date of the initial
application letter to the JAA as the
reference date. The reason given by
Airbus for the request for extension is
related to the technical challenges,
complexity, and the number of new and
novel features on the airplane. On
November 12, 1998, the Manager,
Aircraft Engineering Division, AIR–100,
granted Airbus’ request for the 7-year
period, based on the date of application
to the JAA.
In its letter AI/LE–A 828.0040/99
Issue 3, dated July 20, 2001, Airbus
stated that its target date for type
certification of the Model A380–800 had
been moved from May 2005, to January
2006, to match the delivery date of the
first production airplane. In a
subsequent letter (AI/L 810.0223/98
issue 3, dated January 27, 2006), Airbus
stated that its target date for type
certification is October 2, 2006. In
accordance with 14 CFR 21.17(d)(2),
Airbus chose a new application date of
December 20, 1999, and requested that
the 7-year certification period which
had already been approved be
continued. The FAA has reviewed the
part 25 certification basis for the Model
A380–800 airplane, and no changes are
required based on the new application
date.
The Model A380–800 airplane will be
an all-new, four-engine jet transport
airplane with a full double-deck, twoaisle cabin. The maximum takeoff
weight will be 1.235 million pounds
with a typical three-class layout of 555
passengers.
Type Certification Basis
Under the provisions of 14 CFR 21.17,
Airbus must show that the Model A380–
800 airplane meets the applicable
provisions of 14 CFR part 25, as
amended by Amendments 25–1 through
25–98. If the Administrator finds that
the applicable airworthiness regulations
do not contain adequate or appropriate
safety standards for the Airbus A380–
800 airplane because of novel or
unusual design features, special
conditions are prescribed under the
provisions of 14 CFR 21.16.
In addition to the applicable
airworthiness regulations and special
conditions, the Airbus Model A380–800
airplane must comply with the fuel vent
and exhaust emission requirements of
14 CFR part 34 and the noise
certification requirements of 14 CFR
part 36. In addition, the FAA must issue
a finding of regulatory adequacy
pursuant to section 611 of Public Law
E:\FR\FM\28MRP1.SGM
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]]>Agencies
[Federal Register Volume 71, Number 59 (Tuesday, March 28, 2006)]
[Proposed Rules]
[Pages 15345-15350]
From the Federal Register Online via the Government Printing Office [www.gpo.gov]
[FR Doc No: 06-2973]
=======================================================================
-----------------------------------------------------------------------
DEPARTMENT OF TRANSPORTATION
Federal Aviation Administration
14 CFR Part 25
[Docket No. NM341; Notice No. 25-06-02-SC]
Special Conditions: Airbus Model A380-800 Airplane, Loading
Conditions for Multi-Leg Landing Gear
AGENCY: Federal Aviation Administration (FAA), DOT.
ACTION: Notice of proposed special conditions.
-----------------------------------------------------------------------
SUMMARY: This notice proposes special conditions for the Airbus A380-
800 airplane. This airplane will have novel or unusual design features
when compared to the state of technology envisioned in the
airworthiness standards for transport category airplanes. Many of these
novel or unusual design features are associated with the complex
systems and the
[[Page 15346]]
configuration of the airplane, including its full-length double deck.
For these design features, the applicable airworthiness regulations do
not contain adequate or appropriate safety standards regarding loading
conditions for multi-leg landing gear. These proposed special
conditions contain the additional safety standards that the
Administrator considers necessary to establish a level of safety
equivalent to that established by the existing airworthiness standards.
Additional special conditions will be issued for other novel or unusual
design features of the Airbus Model A380-800 airplane.
DATES: Comments must be received on or before May 12, 2006.
ADDRESSES: Comments on this proposal may be mailed in duplicate to:
Federal Aviation Administration, Transport Airplane Directorate,
Attention: Rules Docket (ANM-113), Docket No. NM341, 1601 Lind Avenue,
SW., Renton, Washington 98055-4056; or delivered in duplicate to the
Transport Airplane Directorate at the above address. All comments must
be marked: Docket No. NM341. Comments may be inspected in the Rules
Docket weekdays, except Federal holidays, between 7:30 a.m. and 4 p.m.
FOR FURTHER INFORMATION CONTACT: Holly Thorson, FAA, International
Branch, ANM-116, Transport Airplane Directorate, Aircraft Certification
Service, 1601 Lind Avenue, SW., Renton, Washington 98055-4056;
telephone (425) 227-1357; facsimile (425) 227-1149.
SUPPLEMENTARY INFORMATION:
Comments Invited
The FAA invites interested persons to participate in this
rulemaking by submitting written comments, data, or views. The most
helpful comments reference a specific portion of the special
conditions, explain the reason for any recommended change, and include
supporting data. We ask that you send us two copies of written
comments.
We will file in the docket all comments we receive as well as a
report summarizing each substantive public contact with FAA personnel
concerning these proposed special conditions. The docket is available
for public inspection before and after the comment closing date. If you
wish to review the docket in person, go to the address in the ADDRESSES
section of this notice between 7:30 a.m. and 4 p.m., Monday through
Friday, except Federal holidays.
We will consider all comments we receive on or before the closing
date for comments. We will consider comments filed late, if it is
possible to do so without incurring expense or delay. We may change the
proposed special conditions in light of the comments we receive.
If you want the FAA to acknowledge receipt of your comments on this
proposal, include with your comments a pre-addressed, stamped postcard
on which the docket number appears. We will stamp the date on the
postcard and mail it back to you.
Background
Airbus applied for FAA certification/validation of the
provisionally-designated Model A3XX-100 in its letter AI/L 810.0223/98,
dated August 12, 1998, to the FAA. Application for certification by the
Joint Aviation Authorities (JAA) of Europe had been made on January 16,
1998, reference AI/L 810.0019/98. In its letter to the FAA, Airbus
requested an extension to the 5-year period for type certification in
accordance with 14 CFR 21.17(c). The request was for an extension to a
7-year period, using the date of the initial application letter to the
JAA as the reference date. The reason given by Airbus for the request
for extension is related to the technical challenges, complexity, and
the number of new and novel features on the airplane. On November 12,
1998, the Manager, Aircraft Engineering Division, AIR-100, granted
Airbus' request for the 7-year period, based on the date of application
to the JAA.
In its letter AI/LE-A 828.0040/99 Issue 3, dated July 20, 2001,
Airbus stated that its target date for type certification of the Model
A380-800 had been moved from May 2005, to January 2006, to match the
delivery date of the first production airplane. In a subsequent letter
(AI/L 810.0223/98 Issue 3, dated January 27, 2006), Airbus stated that
its target date for type certification is October 2, 2006. In
accordance with 14 CFR 21.17(d)(2), Airbus chose a new application date
of December 20, 1999, and requested that the 7-year certification
period which had already been approved be continued. The FAA has
reviewed the part 25 certification basis for the Model A380-800
airplane, and no changes are required based on the new application
date.
The Model A380-800 airplane will be an all-new, four-engine jet
transport airplane with a full double-deck, two-aisle cabin. The
maximum takeoff weight will be 1.235 million pounds with a typical
three-class layout of 555 passengers.
Type Certification Basis
Under the provisions of 14 CFR 21.17, Airbus must show that the
Model A380-800 airplane meets the applicable provisions of 14 CFR part
25, as amended by Amendments 25-1 through 25-98. If the Administrator
finds that the applicable airworthiness regulations do not contain
adequate or appropriate safety standards for the Airbus A380-800
airplane because of novel or unusual design features, special
conditions are prescribed under the provisions of 14 CFR 21.16.
In addition to the applicable airworthiness regulations and special
conditions, the Airbus Model A380-800 airplane must comply with the
fuel vent and exhaust emission requirements of 14 CFR part 34 and the
noise certification requirements of 14 CFR part 36. In addition, the
FAA must issue a finding of regulatory adequacy pursuant to section 611
of Public Law 93-574, the ``Noise Control Act of 1972.''
Special conditions, as defined in 14 CFR 11.19, are issued in
accordance with 14 CFR 11.38 and become part of the type certification
basis in accordance with 14 CFR 21.17(a)(2).
Special conditions are initially applicable to the model for which
they are issued. Should the type certificate for that model be amended
later to include any other model that incorporates the same novel or
unusual design feature, the special conditions would also apply to the
other model under the provisions of 14 CFR 21.101.
Discussion of Novel or Unusual Design Features
The A380 has a multi-leg landing gear arrangement consisting of a
nose gear, two wing mounted gear, and two body mounted gear. This
arrangement is different from the simpler, conventional landing gear
arrangement envisioned by the landing and ground load requirements of
14 CFR part 25. Those regulations assume a landing gear arrangement
comprising a three point suspension system (two main gear and a nose or
tail gear) in which load sharing between the landing gear can be
determined without considering the flexibility of the airframe. In
fact, Sec. 25.477 states that certain Ground Load provisions apply
only to ``airplanes with conventional arrangements of main and nose
gears, or main and tail gears, when normal operating techniques are
used.''
For a five point suspension system, like that of the A380, load
sharing between landing gear must be determined in a rational manner
considering the flexibility of the
[[Page 15347]]
airplane. Therefore, the landing and ground load requirements of 14 CFR
part 25 are not valid, and special conditions specifying the load
conditions appropriate to the multi-leg landing gear on the A380 are
necessary.
Proposed regulatory changes pertaining to landing and ground
handling structural design loads have been developed by a working group
of the Aviation Rulemaking and Advisory Committee (ARAC). The proposal,
dated May 30, 2003, provides design load requirements for various
landing gear configurations, including the multi-leg landing gear
configuration of the A380.
The special conditions proposed in this document are based upon the
regulatory changes proposed by the ARAC working group, as are the
special conditions issued by the European Aviation Safety Agency for
its certification of the A380. For ease of reference, the special
conditions proposed in this document are organized in the same manner
as in the ARAC recommendation. Since the changes proposed by ARAC cover
various landing gear configurations, certain paragraphs of the proposal
are not applicable to the A380. These paragraphs are so indicated in
the section of this notice, entitled ``The Proposed Special
Conditions.''
This notice contains two groups of proposed special conditions. The
first group (Group A) addresses Landing Conditions and includes
proposed special conditions pertaining to the following:
A.1. Landing load conditions and assumptions,
A.2. Symmetric landing load conditions,
A.3. One-gear landing conditions, and
A.4. Side load conditions.
The second group (Group B) addresses other conditions and tests,
including Ground Handling Conditions. It includes proposed special
conditions pertaining to the following:
B.1. Ground handling conditions,
B.2. Taxi, takeoff and landing roll,
B.3. Braked roll conditions,
B.4. Nose-wheel yaw and steering,
B.5. Pivoting,
B.6. Reversed braking,
B.7. Ground load: unsymmetrical loads on multiple-wheel units,
and
B.8. Shock absorption tests.
Applicability
As discussed above, these special conditions are applicable to the
Airbus A380-800 airplane. Should Airbus apply at a later date for a
change to the type certificate to include another model incorporating
the same novel or unusual design features, these special conditions
would apply to that model as well under the provisions of Sec. 21.101.
Conclusion
This action affects only certain novel or unusual design features
of the Airbus A380-800 airplane. It is not a rule of general
applicability.
List of Subjects in 14 CFR Part 25
Aircraft, Aviation safety, Reporting and recordkeeping
requirements.
The authority citation for these special conditions is as follows:
Authority: 49 U.S.C. 106(g), 40113, 44701, 44702, 44704.
The Proposed Special Conditions
Accordingly, pursuant to the authority delegated to me by the
Administrator, the Federal Aviation Administration (FAA) proposes the
following special conditions as part of the type certification basis
for the Airbus A380-800 airplane.
A. Landing Conditions
1. Landing Load Conditions and Assumptions
In lieu of Sec. Sec. 25.473 and 25.477, the following special
conditions apply:
(a) The landing gear and airplane structure must be investigated
for the landing conditions specified in Special Conditions A.2., A.3.,
and A.4. For these conditions, the airplane is assumed to contact the
ground--
(1) In the attitudes defined in Special Conditions A.2. and A.3.
(2) At the descent velocities defined in Special Conditions A.2.
and A.3. The prescribed descent velocities may be modified, if it is
shown that the airplane has design features that make it impossible to
develop these velocities.
(b) Airplane lift, not exceeding airplane weight, may be assumed,
unless the presence of systems or procedures significantly affects the
lift.
(c) The method of analysis of airplane and landing gear loads must
take into account at least the following elements:
(1) Landing gear dynamic characteristics.
(2) Spin-up and spring back.
(3) Rigid body response.
(4) Structural dynamic response of the airframe, if significant.
(5) Each approved tire with nominal characteristics.
(d) The landing gear dynamic characteristics must be validated by
tests as defined in Special Condition B.8., paragraph (a).
(e) The coefficient of friction between the tires and the ground
may be established by considering the effects of skidding velocity and
tire pressure. However, this coefficient of friction need not be more
than 0.8.
2. Symmetric Landing Load Conditions
In lieu of Sec. Sec. 25.479 and 25.481, the following special
conditions apply:
The landing gear and airframe structure must be designed for the
dynamic landing conditions of Special Condition A.2., using the
assumptions specified in Special Condition A.1.
(a) The airplane is assumed to contact the ground--
(1) With an airspeed corresponding to the attitudes specified in
paragraph (c) of this special condition in the following conditions:
(i) Standard sea level conditions, and (ii) at maximum approved
altitude in a hot day temperature of 22.8[deg]C (41[deg]F) above
standard.
The airspeed need not be greater than 1.25V[INF]S0[/INF], or less
than V[INF]S0[/INF], where V[INF]S0[/INF] = the 1-g stalling speed
based on C[INF]NAmax[/INF] at the appropriate weight and in the landing
configuration. The effects of increased ground contact speeds must be
investigated to account for downwind landings for which approval is
desired.
(2) With a limit descent velocity of 3.05 m/sec (10 fps) at the
design landing weight (the maximum weight for landing conditions at
maximum descent velocity); and,
(3) With a limit descent velocity of 1.83 m/sec (6 fps) at the
design takeoff weight (the maximum weight for landing conditions at a
reduced descent velocity).
(b) Not applicable to A380.
(c) For airplanes with nose wheels, the conditions specified in
this paragraph must be investigated assuming the following attitudes:
(1) An attitude in which the nose and main wheels are assumed to
contact the ground simultaneously, as shown in 14 CFR part 25, Appendix
A, Figure 2. For this condition, airplane pitching moment is assumed to
be reacted by the nose gear.
(2) An attitude corresponding to the smallest pitch attitude at
which the main landing gear reach maximum vertical compression before
impact on the nose gear.
(3) An attitude corresponding to either the stalling angle or the
maximum angle allowing clearance with the ground by each part of the
airplane other than any wheel of the main landing gear, in accordance
with 14 CFR part 25, Appendix A, Figure 3, whichever is less.
(4) For aircraft with more than two main landing gear or more than
two wheels per main landing gear unit, each
[[Page 15348]]
intermediate attitude that may be critical.
(d) For airplanes with more than two main landing gear, landing
must be considered on a level runway and, as a separate condition, on a
runway having a convex upward shape that may be approximated by a slope
of 1.5% at main landing gear stations.
3. One-Gear Landing Conditions
In lieu of Sec. 25.483, the following special condition applies:
(a) Not applicable to the A380.
(b) For airplanes with more than two main landing gear, a dynamic
rolled landing condition on a level runway must be considered, using
the assumptions specified in Special Condition A.1., in which--
(1) The airplane is assumed to contact the ground--
(i) At the maximum roll angle attainable within the geometric
limitations of the airplane; (however, the roll angle need not exceed
10 degrees),
(ii) With a limit descent velocity of 2.13 m/sec (7 fps) at the
design landing weight,
(iii) At the critical pitch attitudes and corresponding contact
velocities obtained under Special Conditions No. A.2.
(2) The dynamic analysis must include the contact of all gear
outboard of the airplane centerline on the side of first gear impact.
This condition need not apply to the gear on the opposite side of the
airplane.
(3) Side loads (in the ground reference system) may be assumed to
be zero.
(4) Airplane rolling moments shall be reacted by airplane inertia
forces and by subsequent main gear reactions.
4. Side Load Conditions
In lieu of Sec. 25.485, the following special conditions apply:
For the side load conditions specified in paragraphs (a) and (b)
below, the vertical and drag loads are assumed to act at the wheel axle
centerline, and the side loads are assumed to act at the ground contact
point. The gear loads are balanced by inertia of the airplane.
(a) The most severe combination of loads that are likely to arise
during a lateral drift landing must be taken into account. In the
absence of a more rational analysis of this condition, the following
must be investigated:
(1) A separate condition for each gear, for which the vertical load
is assumed to be 75% of the maximum vertical reaction obtained in
Special Condition A.2. or A.3., whichever is greater. For airplanes
with more than two main landing gear, the vertical load on the other
gear is assumed to be 75% of the correlated vertical load for those
gear in the same condition. The vertical loads for each gear are
combined with drag and side loads of 40% and 25%, respectively, of the
vertical load.
(2) The airplane is assumed to be in the attitude corresponding to
the maximum vertical reaction obtained in Special Condition A.2 or
A.3., whichever is greater.
(3) The shock absorber and tire deflections must be assumed to be
75% of the deflection corresponding to the vertical loads obtained in
Special Condition A.2., whichever is greater.
(b) In addition to the side load conditions specified in paragraph
(a) above, the following side load conditions must be considered for
each main landing gear unit:
(1) A separate condition for each main landing gear unit, for which
the vertical load is assumed to be 50% of the maximum vertical reaction
obtained in Special Condition A.2. For airplanes with more than two
main gear, the vertical load on other gear is assumed to be 50% of the
correlated vertical load for those gear in the same condition. The
vertical loads for each gear are combined with the side loads specified
in paragraph (b)(3) or (b)(4) of this special condition, as applicable.
(2) The airplane is assumed to be in the attitude corresponding to
the maximum vertical reaction obtained in Special Conditions A.2.
(3) For the outboard main landing gear, side loads of 0.8 of the
vertical reaction (on one side) acting inward and 0.6 of the vertical
reaction (on the other side) acting outward as shown in 14 CFR part 25,
Appendix A, Figure 5.
(4) For airplanes with more than two main landing gear, the side
load of each inboard main landing gear is determined by a linear
interpolation between 0.8 and 0.6 of the vertical gear load on that
gear, depending on the lateral position of that gear relative to the
outboard main landing gear. The side loads act in the same direction as
the outboard main gear side loads.
(5) The drag loads may be assumed to be zero.
(6) The shock absorber and tire deflections must be assumed to be
50% of the deflection corresponding to the vertical loads of Special
Conditions A.2.
B. Ground Handling Conditions
1. Ground Handling Conditions
In lieu of Sec. 25.489, the following special conditions apply:
(a) Unless otherwise prescribed, the landing gear and airplane
structure must be investigated for the conditions in Sec. 25.509 and
in Special Conditions. B.2, B.3, B.4, B.5, and B.6, as follows:
(1) The airplane must be assumed to be at the design ramp weight
(the maximum weight for ground handling conditions);
(2) The airplane lift must be assumed to be zero; and
(3) The shock absorbers and tires may be assumed to be in their
static position.
(b) For airplanes with more than two main landing gears, the
airplane must be considered to be on a level runway and, as a separate
condition, on a runway having a convex upward shape that may be
approximated by a slope of 1.5% at the main landing gear stations. The
ground reactions must be distributed to the individual landing gear in
a rational or conservative manner.
2. Taxi, Takeoff and Landing Roll
In lieu of Sec. 25.491, the following special condition applies:
Within the range of appropriate ground speeds and approved weights,
the airplane structure and landing gear are assumed to be subjected to
loads not less than those obtained when the aircraft is operating over
the roughest ground that may reasonably be expected in normal
operation. Steady aerodynamic effects must be considered in a rational
or conservative manner.
3. Braked Roll Conditions
In lieu of Sec. 25.493, the following special conditions apply:
(a) Not applicable to A380.
(b)For an airplane with a nose wheel, the limit vertical load
factor is 1.2 at the design landing weight and 1.0 at the design ramp
weight. A drag reaction equal to the vertical reaction, multiplied by a
coefficient of friction of 0.8, must be combined with the vertical
reaction and applied at the ground contact point of each wheel with
brakes. The following two attitudes, in accordance with14 CFR part 25,
Appendix A, Figure 6, must be considered:
(1) The level attitude with the wheels contacting the ground and
the loads distributed between the main and nose gear. Zero pitching
acceleration is assumed.
(2) The level attitude with only the main gear contacting the
ground and with the pitching moment resisted by angular acceleration.
(c) 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
[[Page 15349]]
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 (e) of this paragraph.
(d) Not applicable to the A380.
(e) A drag reaction lower than that prescribed in Special Condition
B.3 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.
4. Nose-Wheel Yaw and Steering
In lieu of Sec. 25.499, the following special conditions apply:
(a) A vertical load factor of 1.0 at the airplane center of gravity
and a side component at the nose wheel ground contact equal to 0.8 of
the vertical ground reaction at that point are assumed.
(b) With the airplane assumed to be in static equilibrium with the
loads resulting from the use of brakes on one side of the main landing
gear system, the nose gear, its attaching structure, and the fuselage
structure forward of the center of gravity must be designed for the
following loads:
(1) A vertical load factor at the center of gravity of 1.0.
(2) For wheels with brakes applied, the coefficient of friction
must be 0.8. Drag loads are balanced by airplane inertia. Airplane
pitching moment is reacted by the nose gear.
(3) Side and vertical loads at the ground contact point on the nose
gear that are required for static equilibrium.
(4) A side load factor at the airplane center of gravity of zero.
(c) If the loads prescribed in paragraph (b) above result in a nose
gear side load higher than 0.8 times the vertical nose gear load, the
design nose gear side load may be limited to 0.8 times the vertical
load, with unbalanced yawing moments assumed to be resisted by airplane
inertia forces.
(d) For other than the nose gear, its attaching structure, and the
forward fuselage structure, the loading conditions are those prescribed
in paragraph (b) above, except that--
(1) A lower drag reaction may be used if an effective drag force of
0.8 times the vertical reaction cannot be reached under any likely
loading condition; and
(2) The forward acting load at the center of gravity need not
exceed the maximum drag reaction on the main landing gear, determined
in accordance with Special Conditions B.3., paragraph (b).
(e) With the airplane at design ramp weight, and the nose gear in
any steerable position, the combined application of full normal
steering torque and vertical force equal to 1.33 times the maximum
static reaction on the nose gear must be considered in designing the
nose gear, its attaching structure, and the forward fuselage structure.
5. Pivoting
In lieu of Sec. 25.503, the following special condition applies:
The main landing gear and supporting structure must be designed for
the loads induced by pivoting during ground maneuvers in paragraph (b)
below.
(a) Not applicable to A380.
(b) For airplanes with more than two main landing gear, the
following pivoting conditions must be considered:
(1) The following rational pivoting maneuvers must be considered:
(i) Towing at the nose gear at the critical towing angle, no brakes
applied, and separately,
(ii) Application of symmetrical and unsymmetrical forward thrust to
aid pivoting, with and without braking by pilot action on the pedals.
(2) The airplane is assumed to be in static equilibrium, with the
loads being applied at the ground contact points.
(3) The limit vertical load factor must be 1.0, and
(i) For wheels with brakes applied, the coefficient of friction
must be 0.8.
(ii) For wheels with brakes not applied, the ground tire reactions
must be based on reliable tire data.
6. Reversed Braking
In lieu of Sec. 25.507, the following special conditions apply:
(a) The airplane must be in a static ground attitude. Horizontal
reactions parallel to the ground and directed forward must be applied
at the ground contact point of each wheel with brakes. The limit loads
must be equal to 0.55 times the vertical load at each wheel or to the
load developed by 1.2 times the nominal maximum static brake torque,
whichever is less.
(b) For airplanes with nose gears, the pitching moment must be
balanced by rotational inertia.
7. Ground Load: Unsymmetrical Loads on Multiple-Wheel Units
In lieu of Sec. 25.511, subparagraphs (d) and (e), the following
special conditions apply:
(a) Landing conditions. For one and for two deflated tires, the
applied load to each gear unit is assumed to be 60 percent and 50
percent, respectively, of the limit load applied to each gear for each
of the prescribed landing conditions. However, for Special Condition
A.4., paragraph (b), 100 percent of the vertical load must be applied.
Special Condition A.4., paragraph (a)(3), need not be considered with
deflated tires.
(b) Taxiing and ground handling conditions. For one and for two
deflated tires--
(1) The applied side or drag load factor, or both factors, at the
center of gravity must be the most critical value up to 50 percent and
40 percent, respectively, of the limit side or drag load factors, or
both factors, corresponding to the most severe condition resulting from
consideration of the prescribed taxiing and ground handling conditions;
(2) For the braked roll conditions of Special Conditions B.3.,
paragraph (b)(2), the drag loads on each inflated tire may not be less
than those at each tire for the symmetrical load distribution with no
deflated tires;
(3) The vertical load factor at the center of gravity must be 60
percent and 50 percent, respectively, of the factor with no deflated
tires, except that it may not be less than 1g; and
(4) The pivoting condition of Special Condition B.5. and the braked
roll conditions of Special Condition B.3., paragraph (c), need not be
considered with deflated tires.
8. Shock Absorption Tests
In lieu of Sec. 25.723, the following special conditions apply:
(a) The analytical representation of the landing gear dynamic
characteristics that is used in determining the landing loads must be
validated by energy absorption tests. A range of tests must be
conducted to ensure that the analytical representation is valid for the
design conditions specified in Special Conditions A.2. and A.3., if
applicable.
(1) The configurations subjected to energy absorption tests at
limit design conditions must include both the condition with the
maximum energy absorbed by the landing gear and the condition with the
maximum descent velocity obtained from Special Condition A.2. and A.3.
(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.
(b) Each landing gear unit may not fail in a test, demonstrating
its reserve energy absorption capacity, assuming--
(3) The test descent velocity is 120% of that corresponding to the
condition specified in paragraph (b)(1) of this paragraph;
[[Page 15350]]
(4) The effects of wheel spin-up need not be included.
(c) In lieu of the tests prescribed in this paragraph, 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.
Issued in Renton, Washington, on March 20, 2006.
Ali Bahrami,
Manager, Transport Airplane Directorate, Aircraft Certification
Service.
[FR Doc. 06-2973 Filed 3-27-06; 8:45 am]
BILLING CODE 4910-13-P
