[Federal Register Volume 71, Number 59 (Tuesday, March 28, 2006)]
[Proposed Rules]
[Pages 15345-15350]
From the Federal Register Online via the Government Publishing Office [www.gpo.gov]
[FR Doc No: 06-2973]


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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.

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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