Special Conditions: Airbus Model A330-841 and A330-941 (A330 NEO) Airplanes; Interaction of Systems and Structures, 36322-36326 [2017-16416]
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Federal Register / Vol. 82, No. 149 / Friday, August 4, 2017 / Rules and Regulations
flight-control system or flight-envelope
protections (other than load-factor
protection), provided that:
i. The required values are readily
achievable in turns, and
ii. Wings-level pitch-up is
satisfactory.
d. Maximum achievable negative load
factor may be limited by the
characteristics of the electronic flightcontrol system or flight-envelope
protections (other than load-factor
protection), provided that:
i. Pitch-down responsiveness is
satisfactory, and
ii. From level flight, 0g is readily
achievable, or alternatively, a
satisfactory trajectory change is readily
achievable at operational speeds. For
the FAA to consider a trajectory change
as satisfactory, the applicant should
propose and justify a pitch rate that
provides sufficient maneuvering
capability in the most critical scenarios.
e. Compliance demonstration with the
above requirements may be performed
without ice accretion on the airframe.
f. These special conditions do not
impose an upper bound for the normal
load-factor limit, nor do they require
that the limiter exist. If the limit is set
at a value beyond the structural design
limit maneuvering load factor n of
§§ 25.333(b), 25.337(b), and 25.337(c),
then there should be a very obvious
positive tactile feel built into the
controller so that it serves as a deterrent
to inadvertently exceeding the structural
limit.
Issued in Renton, Washington.
Victor Wicklund,
Manager, Transport Standards Branch,
Aircraft Certification Service.
[FR Doc. 2017–16414 Filed 8–3–17; 8:45 am]
BILLING CODE 4910–13–P
DEPARTMENT OF TRANSPORTATION
Federal Aviation Administration
14 CFR Part 25
[Docket No. FAA–2017–0356; Special
Conditions No. 25–696–SC]
Special Conditions: Airbus Model
A330–841 and A330–941 (A330 NEO)
Airplanes; Interaction of Systems and
Structures
Federal Aviation
Administration (FAA), DOT.
ACTION: Final special conditions; request
for comments.
AGENCY:
These special conditions are
issued for the Airbus Model A330 NEO
airplanes. This airplane will have novel
or unusual design features when
SUMMARY:
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compared to the state of technology
envisioned in the airworthiness
standards for transport-category
airplanes. These design features include
systems that, directly or as a result of
failure or malfunction, affect airplane
structural performance. The applicable
airworthiness regulations do not contain
adequate or appropriate safety standards
for this design feature. These 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.
DATES: This action is effective on Airbus
on August 4, 2017. We must receive
your comments by September 18, 2017.
ADDRESSES: Send comments identified
by docket number FAA–2017–0356
using any of the following methods:
• Federal eRegulations Portal: Go to
https://www.regulations.gov/ and follow
the online instructions for sending your
comments electronically.
• Mail: Send comments to Docket
Operations, M–30, U.S. Department of
Transportation (DOT), 1200 New Jersey
Avenue SE., Room W12–140, West
Building Ground Floor, Washington, DC
20590–0001.
• Hand Delivery or Courier: Take
comments to Docket Operations in
Room W12–140 of the West Building
Ground Floor at 1200 New Jersey
Avenue SE., Washington, DC, between 9
a.m. and 5 p.m., Monday through
Friday, except Federal holidays.
• Fax: Fax comments to Docket
Operations at 202–493–2251.
Privacy: The FAA will post all
comments it receives, without change,
to https://www.regulations.gov/,
including any personal information the
commenter provides. Using the search
function of the docket Web site, anyone
can find and read the electronic form of
all comments received into any FAA
docket, including the name of the
individual sending the comment (or
signing the comment for an association,
business, labor union, etc.). DOT’s
complete Privacy Act Statement can be
found in the Federal Register published
on April 11, 2000 (65 FR 19477–19478).
Docket: Background documents or
comments received may be read at
https://www.regulations.gov/ at any time.
Follow the online instructions for
accessing the docket or go to Docket
Operations in Room W12–140 of the
West Building Ground Floor at 1200
New Jersey Avenue SE., Washington,
DC, between 9 a.m. and 5 p.m., Monday
through Friday, except Federal holidays.
FOR FURTHER INFORMATION CONTACT:
Todd Martin, FAA, Airframe and Cabin
Safety, ANM–115, Transport Airplane
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Directorate, Aircraft Certification
Service, 1601 Lind Avenue SW.,
Renton, Washington 98057–3356;
telephone 425–227–1178; facsimile
425–227–1320.
SUPPLEMENTARY INFORMATION:
The FAA has determined that notice
of, and opportunity for prior public
comment on, these special conditions is
impracticable because these procedures
would significantly delay issuance of
the design approval and thus delivery of
the affected airplanes.
In addition, the substance of these
special conditions has been subject to
the public comment process in several
prior instances with no substantive
comments received. The FAA therefore
finds it unnecessary to delay the
effective date and finds that good cause
exists for making these special
conditions effective upon publication in
the Federal Register.
Comments Invited
We invite interested people to take
part in this rulemaking by sending
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 will consider all comments we
receive by the closing date for
comments. We may change these special
conditions based on the comments we
receive.
Background
On January 20, 2015, Airbus applied
for an amendment to Type Certificate
no. A46NM to include the new Model
A330–841 (A330–800NEO) and A330–
941 (A330–900NEO) airplanes,
collectively marketed as Model
A330NEO airplanes. These airplanes,
which are derivatives of the Model
A330–200 and A330–300 airplanes
currently approved under Type
Certificate no. A46NM, are wide-body,
jet-engine airplanes with a maximum
takeoff weight of 533,519 pounds, and a
passenger capacity of 257 (A330–841);
or a maximum takeoff weight of 535,503
pounds, and a passenger capacity of 287
(A330–941).
Type Certification Basis
Under the provisions of Title 14, Code
of Federal Regulations (14 CFR) 21.101,
Airbus must show that the Model
A330NEO airplanes meet the applicable
provisions of the regulations listed in
Type Certificate No. A46NM, or the
applicable regulations in effect on the
date of application for the change except
for earlier amendments as agreed upon
by the FAA.
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Federal Register / Vol. 82, No. 149 / Friday, August 4, 2017 / Rules and Regulations
If the Administrator finds that the
applicable airworthiness regulations
(i.e., 14 CFR part 25) do not contain
adequate or appropriate safety standards
for Model A330NEO airplanes because
of a novel or unusual design feature,
special conditions are prescribed under
the provisions of § 21.16.
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, or should any other
model already included on the same
type certificate be modified to
incorporate the same novel or unusual
design feature, these special conditions
would also apply to the other model
under § 21.101.
In addition to the applicable
airworthiness regulations and special
conditions, the Airbus Model A330NEO
airplanes must comply with the fuelvent and exhaust-emission requirements
of 14 CFR part 34 and the noisecertification requirements of 14 CFR
part 36.
The FAA issues special conditions, as
defined in 14 CFR 11.19, in accordance
with § 11.38, and they become part of
the type certification basis under
§ 21.101.
Novel or Unusual Design Features
The Airbus Model A330NEO
airplanes will incorporate the following
novel or unusual design features:
Systems that, directly or as a result of
failure or malfunction, affect airplane
structural performance. That is, the
airplane’s systems affect how it
responds in maneuver and gust
conditions, and thereby affect its
structural capability. These systems may
also affect the aeroelastic stability of the
airplane. Such systems include flight
control systems, autopilots, stability
augmentation systems, load alleviation
systems, and fuel management systems.
These systems represent novel and
unusual features when compared to the
technology envisioned in the current
airworthiness standards.
Discussion
Special conditions have been applied
on past airplane programs to require
consideration of the effects of systems
on structures. The regulatory authorities
and industry developed standardized
criteria in the Aviation Rulemaking
Advisory Committee (ARAC) forum
based on the criteria defined in
Advisory Circular (AC) 25.672–1, dated
November 15, 1983. The ARAC
recommendations have been
incorporated in European Aviation
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Safety Agency (EASA) Certification
Specifications (CS) 25.302 and CS 25
Appendix K, which are applicable to
Airbus. FAA rulemaking on this subject
is not complete, thus the need for the
special conditions.
The special conditions are similar to
those previously applied to other
airplane models and to the requirements
of CS 25.302. The major differences
between these special conditions and
the current CS 25.302 are as follows:
(1) Both the special conditions and CS
25.302 (and by reference Appendix K)
specify the design load conditions to be
considered. Effects of Systems on
Structure, special conditions 2.a. and
3.b.i., clarify that, in some cases,
different load conditions are to be
considered due to other special
conditions or equivalent-level-of-safety
findings.
(2) Both the special conditions (see
special condition 5, below) and CS
25.302 allow consideration of the
probability of being in a dispatched
configuration when assessing
subsequent failures and potential
‘‘continuation of flight’’ loads. The
special conditions, however, also allow
using probability when assessing
failures that induce loads at the ‘‘time
of occurrence,’’ whereas CS 25.302 does
not.
These 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.
Applicability
As discussed above, these special
conditions are applicable to Airbus
Model A330NEO airplanes. 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 feature, these special
conditions would apply to that model as
well.
Conclusion
This action affects only certain novel
or unusual design features on one model
series of airplanes. It is not a rule of
general applicability.
The substance of these special
conditions has been subject to the notice
and comment period in several prior
instances and has been derived without
substantive change from those
previously issued. It is unlikely that
prior public comment would result in a
significant change from the substance
contained herein. Therefore, because a
delay would significantly affect the
certification of the airplane, which is
imminent, the FAA has determined that
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36323
prior public notice and comment are
unnecessary and impracticable, and
good cause exists for adopting these
special conditions upon publication in
the Federal Register. The FAA is
requesting comments to allow interested
persons to submit views that may not
have been submitted in response to the
prior opportunities for comment
described above.
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 Special Conditions
Accordingly, pursuant to the
authority delegated to me by the
Administrator, the following special
conditions are issued as part of the type
certification basis for Airbus Model
A330–841 and A330–941 airplanes.
For airplanes equipped with systems
that affect structural performance, either
directly or as a result of a failure or
malfunction, the influence of these
systems and their failure conditions
must be taken into account when
showing compliance with the
requirements of part 25, subparts C and
D.
For airplanes equipped with flightcontrol systems, autopilots, stabilityaugmentation systems, load-alleviation
systems, fuel-management systems, and
other systems that either directly, or as
a result of failure or malfunction, affect
structural performance, the following
criteria must be used for showing
compliance. If these special conditions
are used for other systems, it may be
necessary to adapt the criteria to the
specific system.
1. The criteria defined herein only
address the direct structural
consequences of the system responses
and performance. They cannot be
considered in isolation, but should be
included in the overall safety evaluation
of the airplane. These criteria may, in
some instances, duplicate standards
already established for this evaluation.
These criteria are only applicable to
structure the failure of which could
prevent continued safe flight and
landing. Specific criteria that define
acceptable limits on handling
characteristics or stability requirements,
when operating in the system-degraded
or inoperative mode, are not provided in
these special conditions.
2. Depending upon the specific
characteristics of the airplane,
additional studies that go beyond the
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Federal Register / Vol. 82, No. 149 / Friday, August 4, 2017 / Rules and Regulations
airplane (e.g., system-failure conditions
that induce loads, change the response
of the airplane to inputs such as gusts
or pilot actions, or lower flutter
margins).
Effects of Systems on Structures
1. General. The following criteria will
be used in determining the influence of
a system and its failure conditions on
the airplane structure.
2. System fully operative. With the
system fully operative, the following
apply:
a. Limit loads must be derived in all
normal operating configurations of the
system from all the limit conditions
specified in part 25, subpart C (or
defined by special conditions or
findings of equivalent level of safety in
lieu of those specified in subpart C),
taking into account any special behavior
of such a system or associated functions,
or any effect on the structural
performance of the airplane that may
occur up to the limit loads. In
particular, any significant nonlinearity
(rate of displacement of control surface,
thresholds, or any other system
nonlinearities) must be accounted for in
a realistic or conservative way when
deriving limit loads from limit
conditions.
b. The airplane must meet the
strength requirements of part 25 (static
strength, residual strength), using the
specified factors to derive ultimate loads
from the limit loads defined above. The
effect of nonlinearities must be
investigated beyond limit conditions to
ensure that the behavior of the system
presents no anomaly compared to the
behavior below limit conditions.
However, conditions beyond limit
conditions need not be considered when
it can be shown that the airplane has
design features that will not allow it to
exceed those limit conditions.
c. The airplane must meet the
aeroelastic stability requirements of
§ 25.629.
3. System in the failure condition. For
any system-failure condition not shown
to be extremely improbable, the
following apply:
a. At the time of occurrence. Starting
from 1g level flight conditions, a
realistic scenario, including pilot
corrective actions, must be established
to determine the loads occurring at the
time of failure and immediately after the
failure.
i. For static-strength substantiation,
these loads, multiplied by an
appropriate factor of safety that is
related to the probability of occurrence
of the failure, are ultimate loads to be
considered for design. The factor of
safety is defined in Figure 1, below.
ii. For residual-strength
substantiation, the airplane must be able
to withstand two thirds of the ultimate
loads defined in special condition 3.a.i.
For pressurized cabins, these loads must
be combined with the normal operating
differential pressure.
iii. Freedom from aeroelastic
instability must be shown up to the
speeds defined in § 25.629(b)(2). For
failure conditions that result in speeds
beyond VC/MC, freedom from
aeroelastic instability must be shown to
increased speeds, so that the margins
intended by § 25.629(b)(2) are
maintained.
iv. Failures of the system that result
in forced structural vibrations
(oscillatory failures) must not produce
loads that could result in detrimental
deformation of primary structure.
b. For the continuation of the flight.
For the airplane in the system-failed
state, and considering any appropriate
reconfiguration and flight limitations,
the following apply:
i. The loads derived from the
following conditions (or defined by
special conditions or findings of
equivalent level of safety in lieu of the
following conditions) at speeds up to
VC/MC (or the speed limitation
prescribed for the remainder of the
flight) must be determined:
1. The limit symmetrical maneuvering
conditions specified in §§ 25.331 and
25.345.
2. the limit gust and turbulence
conditions specified in §§ 25.341 and
25.345.
3. the limit rolling conditions
specified in § 25.349, and the limit
unsymmetrical conditions specified in
§§ 25.367, and 25.427(b) and (c).
4. the limit yaw-maneuvering
conditions specified in § 25.351.
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ER04AU17.015
criteria provided in these special
conditions may be required to
demonstrate the airplane’s capability to
meet other realistic conditions, such as
alternative gust or maneuver
descriptions for an airplane equipped
with a load-alleviation system.
3. The following definitions are
applicable to these special conditions.
a. Structural performance: Capability
of the airplane to meet the structural
requirements of part 25.
b. Flight limitations: Limitations that
can be applied to the airplane flight
conditions following an in-flight
occurrence, and that are included in the
airplane flight manual (e.g., speed
limitations, avoidance of severe weather
conditions, etc.).
c. Operational limitations:
Limitations, including flight limitations,
that can be applied to the airplane
operating conditions before dispatch
(e.g., fuel, payload and Master
Minimum Equipment List limitations).
d. Probabilistic terms: Terms such as
probable, improbable, and extremely
improbable, as used in these special
conditions, are the same as those used
in § 25.1309.
e. Failure condition: This term is the
same as that used in § 25.1309.
However, these special conditions apply
only to system-failure conditions that
affect the structural performance of the
Federal Register / Vol. 82, No. 149 / Friday, August 4, 2017 / Rules and Regulations
36325
safety depending on the probability of
being in this failure state. The factor of
safety is defined in Figure 2, below.
Qj = (Tj)(Pj)
iii. For residual-strength
substantiation, the airplane must be able
to withstand two-thirds of the ultimate
loads defined in paragraph 3.b.ii. of
these special conditions. For
pressurized cabins, these loads must be
combined with the normal operating
differential pressure.
iv. If the loads induced by the failure
condition have a significant effect on
fatigue or damage tolerance, then their
effects must be taken into account.
v. Freedom from aeroelastic
instability must be shown up to a speed
determined from Figure 3, below.
Flutter clearance speeds V′ and V″ may
be based on the speed limitation
specified for the remainder of the flight
using the margins defined by
§ 25.629(b).
system-failure condition, combined
with any damage required or selected
for investigation by § 25.571(b).
c. Consideration of certain failure
conditions may be required by other
sections of part 25 regardless of
calculated system reliability. Where
analysis shows the probability of these
failure conditions to be less than 10¥9
per flight hour, criteria other than those
specified in this paragraph may be used
for structural substantiation to show
continued safe flight and landing.
4. Failure indications. For systemfailure detection and indication, the
following apply:
a. The system must be checked for
failure conditions, not extremely
improbable, that degrade the structural
capability below the level required by
part 25, or that significantly reduce the
reliability of the remaining system. As
far as reasonably practicable, the
flightcrew must be made aware of these
failures before flight. Certain elements
of the control system, such as
mechanical and hydraulic components,
may use special periodic inspections,
and electronic components may use
daily checks, in lieu of detection and
indication systems, to achieve the
objective of this requirement. These
certification-maintenance requirements
Where:
Tj = Average time spent in failure mode j (in
hours)
Pj = Probability of occurrence of failure mode
j (per hour)
Note: If Pj is greater than 10¥3 per flight
hour, then a 1.5 factor of safety must be
applied to all limit load conditions specified
in part 25, subpart C.
V′ = Clearance speed as defined by
§ 25.629(b)(2).
V″ = Clearance speed as defined by
§ 25.629(b)(1).
Qj = (Tj)(Pj)
Where:
Tj = Average time spent in failure mode j (in
hours)
Pj = Probability of occurrence of failure mode
j (per hour)
Note: If Pj is greater than 10¥3 per flight
hour, then the flutter clearance speed must
not be less than V″.
vi. Freedom from aeroelastic
instability must also be shown up to V′
in Figure 3, above, for any probable
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ER04AU17.017
ii. For static-strength substantiation,
each part of the structure must be able
to withstand the loads in special
condition 3.b.i., multiplied by a factor of
ER04AU17.016
5. the limit ground-loading conditions
specified in §§ 25.473, 25.491,
25.493(d), and 25.503.
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Federal Register / Vol. 82, No. 149 / Friday, August 4, 2017 / Rules and Regulations
must be limited to components that are
not readily detectable by normal
detection-and-indication systems, and
where service history shows that
inspections will provide an adequate
level of safety.
b. The existence of any failure
condition, not extremely improbable,
during flight, that could significantly
affect the structural capability of the
airplane, and for which the associated
reduction in airworthiness can be
minimized by suitable flight limitations,
must be signaled to the flightcrew. For
example, failure conditions that result
in a factor of safety between the airplane
strength and the loads of part 25,
subpart C below 1.25, or flutter margins
below V″, must be signaled to the crew
during flight.
5. Dispatch with known failure
conditions. If the airplane is to be
dispatched in a known system-failure
condition that affects structural
performance, or that affects the
reliability of the remaining system to
maintain structural performance, then
the provisions of these special
conditions must be met, including the
provisions of special condition 2 for the
dispatched condition, and special
condition 3 for subsequent failures.
Expected operational limitations may be
taken into account in establishing Pj as
the probability of failure occurrence for
determining the safety margin in Figure
1. Flight limitations and expected
operational limitations may be taken
into account in establishing Qj as the
combined probability of being in the
dispatched failure condition and the
subsequent failure condition for the
safety margins in Figures 2 and 3. These
limitations must be such that the
probability of being in this combined
failure state, and then subsequently
encountering limit load conditions, is
extremely improbable. No reduction in
these safety margins is allowed if the
subsequent system-failure rate is greater
than 10¥3 per flight hour.
Issued in Renton, Washington.
Victor Wicklund,
Manager, Transport Standards Branch,
Aircraft Certification Service.
[FR Doc. 2017–16416 Filed 8–3–17; 8:45 am]
BILLING CODE 4910–13–P
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DEPARTMENT OF TRANSPORTATION
Federal Aviation Administration
14 CFR Part 25
[Docket No. FAA–2017–0732; Special
Conditions No. 25–697–SC]
Special Conditions: Embraer S.A.,
Model ERJ 190–300 Series Airplanes;
Design Roll Maneuver for Electronic
Flight Controls
Federal Aviation
Administration (FAA), DOT.
ACTION: Final special conditions; request
for comments.
AGENCY:
These special conditions are
issued for the Embraer S.A. (Embraer)
Model ERJ 190–300 series airplanes.
These airplanes will have a novel or
unusual design feature when compared
to the state of technology envisioned in
the airworthiness standards for
transport category airplanes. This design
feature is an electronic flight control
system (EFCS) that provides control of
the airplane through pilot inputs to the
flight computer. The applicable
airworthiness regulations do not contain
adequate or appropriate safety standards
for this design feature. These 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.
DATES: This action is effective on
Embraer on August 4, 2017. We must
receive your comments by September
18, 2017.
ADDRESSES: Send comments identified
by docket number FAA–2017–0732
using any of the following methods:
• Federal eRegulations Portal: Go to
https://www.regulations.gov/and follow
the online instructions for sending your
comments electronically.
• Mail: Send comments to Docket
Operations, M–30, U.S. Department of
Transportation (DOT), 1200 New Jersey
Avenue SE., Room W12–140, West
Building Ground Floor, Washington, DC
20590–0001.
• Hand Delivery or Courier: Take
comments to Docket Operations in
Room W12–140 of the West Building
Ground Floor at 1200 New Jersey
Avenue SE., Washington, DC, between
9 a.m. and 5 p.m., Monday through
Friday, except Federal holidays.
• Fax: Fax comments to Docket
Operations at 202–493–2251.
Privacy: The FAA will post all
comments it receives, without change,
to https://www.regulations.gov/,
including any personal information the
commenter provides. Using the search
SUMMARY:
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Sfmt 4700
function of the docket Web site, anyone
can find and read the electronic form of
all comments received into any FAA
docket, including the name of the
individual sending the comment (or
signing the comment for an association,
business, labor union, etc.). DOT’s
complete Privacy Act Statement can be
found in the Federal Register published
on April 11, 2000 (65 FR 19477–19478).
Docket: Background documents or
comments received may be read at
https://www.regulations.gov/ at any time.
Follow the online instructions for
accessing the docket or go to Docket
Operations in Room W12–140 of the
West Building Ground Floor at 1200
New Jersey Avenue SE., Washington,
DC, between 9 a.m. and 5 p.m., Monday
through Friday, except Federal holidays.
FOR FURTHER INFORMATION CONTACT: Greg
Schneider, FAA, Airframe and Cabin
Safety Branch, ANM–115, Transport
Airplane Directorate, Aircraft
Certification Service, 1601 Lind Avenue
SW., Renton, Washington, 98057–3356;
telephone 425–227–2116; facsimile
425–227–1320.
SUPPLEMENTARY INFORMATION: The FAA
has determined that notice of, and
opportunity for prior public comment
on, these special conditions is
impracticable because these procedures
would delay issuance of the design
approval and thus delivery of the
affected airplane.
In addition, the substance of these
special conditions has been subject to
the public comment process in several
prior instances with no substantive
comments received. The FAA finds it is
unnecessary to delay the effective date
and finds that good cause exists for
adopting these special conditions upon
publication in the Federal Register.
Comments Invited
The FAA is requesting comments to
allow interested persons to submit
views that may not have been submitted
in response to the prior opportunities
for comment described above. We invite
interested people to take part in this
rulemaking by sending 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 will consider all comments we
receive by the closing date for
comments. We may change these special
conditions based on the comments we
receive.
Background
On September 13, 2013, Embraer
applied for an amendment to Type
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Agencies
[Federal Register Volume 82, Number 149 (Friday, August 4, 2017)]
[Rules and Regulations]
[Pages 36322-36326]
From the Federal Register Online via the Government Publishing Office [www.gpo.gov]
[FR Doc No: 2017-16416]
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DEPARTMENT OF TRANSPORTATION
Federal Aviation Administration
14 CFR Part 25
[Docket No. FAA-2017-0356; Special Conditions No. 25-696-SC]
Special Conditions: Airbus Model A330-841 and A330-941 (A330 NEO)
Airplanes; Interaction of Systems and Structures
AGENCY: Federal Aviation Administration (FAA), DOT.
ACTION: Final special conditions; request for comments.
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SUMMARY: These special conditions are issued for the Airbus Model A330
NEO airplanes. 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. These design
features include systems that, directly or as a result of failure or
malfunction, affect airplane structural performance. The applicable
airworthiness regulations do not contain adequate or appropriate safety
standards for this design feature. These 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.
DATES: This action is effective on Airbus on August 4, 2017. We must
receive your comments by September 18, 2017.
ADDRESSES: Send comments identified by docket number FAA-2017-0356
using any of the following methods:
Federal eRegulations Portal: Go to https://www.regulations.gov/ and follow the online instructions for sending
your comments electronically.
Mail: Send comments to Docket Operations, M-30, U.S.
Department of Transportation (DOT), 1200 New Jersey Avenue SE., Room
W12-140, West Building Ground Floor, Washington, DC 20590-0001.
Hand Delivery or Courier: Take comments to Docket
Operations in Room W12-140 of the West Building Ground Floor at 1200
New Jersey Avenue SE., Washington, DC, between 9 a.m. and 5 p.m.,
Monday through Friday, except Federal holidays.
Fax: Fax comments to Docket Operations at 202-493-2251.
Privacy: The FAA will post all comments it receives, without
change, to https://www.regulations.gov/, including any personal
information the commenter provides. Using the search function of the
docket Web site, anyone can find and read the electronic form of all
comments received into any FAA docket, including the name of the
individual sending the comment (or signing the comment for an
association, business, labor union, etc.). DOT's complete Privacy Act
Statement can be found in the Federal Register published on April 11,
2000 (65 FR 19477-19478).
Docket: Background documents or comments received may be read at
https://www.regulations.gov/ at any time. Follow the online instructions
for accessing the docket or go to Docket Operations in Room W12-140 of
the West Building Ground Floor at 1200 New Jersey Avenue SE.,
Washington, DC, between 9 a.m. and 5 p.m., Monday through Friday,
except Federal holidays.
FOR FURTHER INFORMATION CONTACT: Todd Martin, FAA, Airframe and Cabin
Safety, ANM-115, Transport Airplane Directorate, Aircraft Certification
Service, 1601 Lind Avenue SW., Renton, Washington 98057-3356; telephone
425-227-1178; facsimile 425-227-1320.
SUPPLEMENTARY INFORMATION:
The FAA has determined that notice of, and opportunity for prior
public comment on, these special conditions is impracticable because
these procedures would significantly delay issuance of the design
approval and thus delivery of the affected airplanes.
In addition, the substance of these special conditions has been
subject to the public comment process in several prior instances with
no substantive comments received. The FAA therefore finds it
unnecessary to delay the effective date and finds that good cause
exists for making these special conditions effective upon publication
in the Federal Register.
Comments Invited
We invite interested people to take part in this rulemaking by
sending 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 will consider all comments we receive by the closing date for
comments. We may change these special conditions based on the comments
we receive.
Background
On January 20, 2015, Airbus applied for an amendment to Type
Certificate no. A46NM to include the new Model A330-841 (A330-800NEO)
and A330-941 (A330-900NEO) airplanes, collectively marketed as Model
A330NEO airplanes. These airplanes, which are derivatives of the Model
A330-200 and A330-300 airplanes currently approved under Type
Certificate no. A46NM, are wide-body, jet-engine airplanes with a
maximum takeoff weight of 533,519 pounds, and a passenger capacity of
257 (A330-841); or a maximum takeoff weight of 535,503 pounds, and a
passenger capacity of 287 (A330-941).
Type Certification Basis
Under the provisions of Title 14, Code of Federal Regulations (14
CFR) 21.101, Airbus must show that the Model A330NEO airplanes meet the
applicable provisions of the regulations listed in Type Certificate No.
A46NM, or the applicable regulations in effect on the date of
application for the change except for earlier amendments as agreed upon
by the FAA.
[[Page 36323]]
If the Administrator finds that the applicable airworthiness
regulations (i.e., 14 CFR part 25) do not contain adequate or
appropriate safety standards for Model A330NEO airplanes because of a
novel or unusual design feature, special conditions are prescribed
under the provisions of Sec. 21.16.
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, or should any other model already included on
the same type certificate be modified to incorporate the same novel or
unusual design feature, these special conditions would also apply to
the other model under Sec. 21.101.
In addition to the applicable airworthiness regulations and special
conditions, the Airbus Model A330NEO airplanes 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.
The FAA issues special conditions, as defined in 14 CFR 11.19, in
accordance with Sec. 11.38, and they become part of the type
certification basis under Sec. 21.101.
Novel or Unusual Design Features
The Airbus Model A330NEO airplanes will incorporate the following
novel or unusual design features:
Systems that, directly or as a result of failure or malfunction,
affect airplane structural performance. That is, the airplane's systems
affect how it responds in maneuver and gust conditions, and thereby
affect its structural capability. These systems may also affect the
aeroelastic stability of the airplane. Such systems include flight
control systems, autopilots, stability augmentation systems, load
alleviation systems, and fuel management systems. These systems
represent novel and unusual features when compared to the technology
envisioned in the current airworthiness standards.
Discussion
Special conditions have been applied on past airplane programs to
require consideration of the effects of systems on structures. The
regulatory authorities and industry developed standardized criteria in
the Aviation Rulemaking Advisory Committee (ARAC) forum based on the
criteria defined in Advisory Circular (AC) 25.672-1, dated November 15,
1983. The ARAC recommendations have been incorporated in European
Aviation Safety Agency (EASA) Certification Specifications (CS) 25.302
and CS 25 Appendix K, which are applicable to Airbus. FAA rulemaking on
this subject is not complete, thus the need for the special conditions.
The special conditions are similar to those previously applied to
other airplane models and to the requirements of CS 25.302. The major
differences between these special conditions and the current CS 25.302
are as follows:
(1) Both the special conditions and CS 25.302 (and by reference
Appendix K) specify the design load conditions to be considered.
Effects of Systems on Structure, special conditions 2.a. and 3.b.i.,
clarify that, in some cases, different load conditions are to be
considered due to other special conditions or equivalent-level-of-
safety findings.
(2) Both the special conditions (see special condition 5, below)
and CS 25.302 allow consideration of the probability of being in a
dispatched configuration when assessing subsequent failures and
potential ``continuation of flight'' loads. The special conditions,
however, also allow using probability when assessing failures that
induce loads at the ``time of occurrence,'' whereas CS 25.302 does not.
These 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.
Applicability
As discussed above, these special conditions are applicable to
Airbus Model A330NEO airplanes. 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 feature, these special conditions
would apply to that model as well.
Conclusion
This action affects only certain novel or unusual design features
on one model series of airplanes. It is not a rule of general
applicability.
The substance of these special conditions has been subject to the
notice and comment period in several prior instances and has been
derived without substantive change from those previously issued. It is
unlikely that prior public comment would result in a significant change
from the substance contained herein. Therefore, because a delay would
significantly affect the certification of the airplane, which is
imminent, the FAA has determined that prior public notice and comment
are unnecessary and impracticable, and good cause exists for adopting
these special conditions upon publication in the Federal Register. The
FAA is requesting comments to allow interested persons to submit views
that may not have been submitted in response to the prior opportunities
for comment described above.
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 Special Conditions
Accordingly, pursuant to the authority delegated to me by the
Administrator, the following special conditions are issued as part of
the type certification basis for Airbus Model A330-841 and A330-941
airplanes.
For airplanes equipped with systems that affect structural
performance, either directly or as a result of a failure or
malfunction, the influence of these systems and their failure
conditions must be taken into account when showing compliance with the
requirements of part 25, subparts C and D.
For airplanes equipped with flight-control systems, autopilots,
stability-augmentation systems, load-alleviation systems, fuel-
management systems, and other systems that either directly, or as a
result of failure or malfunction, affect structural performance, the
following criteria must be used for showing compliance. If these
special conditions are used for other systems, it may be necessary to
adapt the criteria to the specific system.
1. The criteria defined herein only address the direct structural
consequences of the system responses and performance. They cannot be
considered in isolation, but should be included in the overall safety
evaluation of the airplane. These criteria may, in some instances,
duplicate standards already established for this evaluation. These
criteria are only applicable to structure the failure of which could
prevent continued safe flight and landing. Specific criteria that
define acceptable limits on handling characteristics or stability
requirements, when operating in the system-degraded or inoperative
mode, are not provided in these special conditions.
2. Depending upon the specific characteristics of the airplane,
additional studies that go beyond the
[[Page 36324]]
criteria provided in these special conditions may be required to
demonstrate the airplane's capability to meet other realistic
conditions, such as alternative gust or maneuver descriptions for an
airplane equipped with a load-alleviation system.
3. The following definitions are applicable to these special
conditions.
a. Structural performance: Capability of the airplane to meet the
structural requirements of part 25.
b. Flight limitations: Limitations that can be applied to the
airplane flight conditions following an in-flight occurrence, and that
are included in the airplane flight manual (e.g., speed limitations,
avoidance of severe weather conditions, etc.).
c. Operational limitations: Limitations, including flight
limitations, that can be applied to the airplane operating conditions
before dispatch (e.g., fuel, payload and Master Minimum Equipment List
limitations).
d. Probabilistic terms: Terms such as probable, improbable, and
extremely improbable, as used in these special conditions, are the same
as those used in Sec. 25.1309.
e. Failure condition: This term is the same as that used in Sec.
25.1309. However, these special conditions apply only to system-failure
conditions that affect the structural performance of the airplane
(e.g., system-failure conditions that induce loads, change the response
of the airplane to inputs such as gusts or pilot actions, or lower
flutter margins).
Effects of Systems on Structures
1. General. The following criteria will be used in determining the
influence of a system and its failure conditions on the airplane
structure.
2. System fully operative. With the system fully operative, the
following apply:
a. Limit loads must be derived in all normal operating
configurations of the system from all the limit conditions specified in
part 25, subpart C (or defined by special conditions or findings of
equivalent level of safety in lieu of those specified in subpart C),
taking into account any special behavior of such a system or associated
functions, or any effect on the structural performance of the airplane
that may occur up to the limit loads. In particular, any significant
nonlinearity (rate of displacement of control surface, thresholds, or
any other system nonlinearities) must be accounted for in a realistic
or conservative way when deriving limit loads from limit conditions.
b. The airplane must meet the strength requirements of part 25
(static strength, residual strength), using the specified factors to
derive ultimate loads from the limit loads defined above. The effect of
nonlinearities must be investigated beyond limit conditions to ensure
that the behavior of the system presents no anomaly compared to the
behavior below limit conditions. However, conditions beyond limit
conditions need not be considered when it can be shown that the
airplane has design features that will not allow it to exceed those
limit conditions.
c. The airplane must meet the aeroelastic stability requirements of
Sec. 25.629.
3. System in the failure condition. For any system-failure
condition not shown to be extremely improbable, the following apply:
a. At the time of occurrence. Starting from 1g level flight
conditions, a realistic scenario, including pilot corrective actions,
must be established to determine the loads occurring at the time of
failure and immediately after the failure.
i. For static-strength substantiation, these loads, multiplied by
an appropriate factor of safety that is related to the probability of
occurrence of the failure, are ultimate loads to be considered for
design. The factor of safety is defined in Figure 1, below.
[GRAPHIC] [TIFF OMITTED] TR04AU17.015
ii. For residual-strength substantiation, the airplane must be able
to withstand two thirds of the ultimate loads defined in special
condition 3.a.i. For pressurized cabins, these loads must be combined
with the normal operating differential pressure.
iii. Freedom from aeroelastic instability must be shown up to the
speeds defined in Sec. 25.629(b)(2). For failure conditions that
result in speeds beyond VC/MC, freedom from
aeroelastic instability must be shown to increased speeds, so that the
margins intended by Sec. 25.629(b)(2) are maintained.
iv. Failures of the system that result in forced structural
vibrations (oscillatory failures) must not produce loads that could
result in detrimental deformation of primary structure.
b. For the continuation of the flight. For the airplane in the
system-failed state, and considering any appropriate reconfiguration
and flight limitations, the following apply:
i. The loads derived from the following conditions (or defined by
special conditions or findings of equivalent level of safety in lieu of
the following conditions) at speeds up to VC/MC
(or the speed limitation prescribed for the remainder of the flight)
must be determined:
1. The limit symmetrical maneuvering conditions specified in
Sec. Sec. 25.331 and 25.345.
2. the limit gust and turbulence conditions specified in Sec. Sec.
25.341 and 25.345.
3. the limit rolling conditions specified in Sec. 25.349, and the
limit unsymmetrical conditions specified in Sec. Sec. 25.367, and
25.427(b) and (c).
4. the limit yaw-maneuvering conditions specified in Sec. 25.351.
[[Page 36325]]
5. the limit ground-loading conditions specified in Sec. Sec.
25.473, 25.491, 25.493(d), and 25.503.
ii. For static-strength substantiation, each part of the structure
must be able to withstand the loads in special condition 3.b.i.,
multiplied by a factor of safety depending on the probability of being
in this failure state. The factor of safety is defined in Figure 2,
below.
[GRAPHIC] [TIFF OMITTED] TR04AU17.016
Qj = (Tj)(Pj)
Where:
Tj = Average time spent in failure mode j (in hours)
Pj = Probability of occurrence of failure mode j (per
hour)
Note: If Pj is greater than 10-\3\ per
flight hour, then a 1.5 factor of safety must be applied to all
limit load conditions specified in part 25, subpart C.
iii. For residual-strength substantiation, the airplane must be
able to withstand two-thirds of the ultimate loads defined in paragraph
3.b.ii. of these special conditions. For pressurized cabins, these
loads must be combined with the normal operating differential pressure.
iv. If the loads induced by the failure condition have a
significant effect on fatigue or damage tolerance, then their effects
must be taken into account.
v. Freedom from aeroelastic instability must be shown up to a speed
determined from Figure 3, below. Flutter clearance speeds V' and V''
may be based on the speed limitation specified for the remainder of the
flight using the margins defined by Sec. 25.629(b).
[GRAPHIC] [TIFF OMITTED] TR04AU17.017
V' = Clearance speed as defined by Sec. 25.629(b)(2).
V'' = Clearance speed as defined by Sec. 25.629(b)(1).
Qj = (Tj)(Pj)
Where:
Tj = Average time spent in failure mode j (in hours)
Pj = Probability of occurrence of failure mode j (per
hour)
Note: If Pj is greater than 10-\3\ per
flight hour, then the flutter clearance speed must not be less than
V''.
vi. Freedom from aeroelastic instability must also be shown up to
V' in Figure 3, above, for any probable system-failure condition,
combined with any damage required or selected for investigation by
Sec. 25.571(b).
c. Consideration of certain failure conditions may be required by
other sections of part 25 regardless of calculated system reliability.
Where analysis shows the probability of these failure conditions to be
less than 10-\9\ per flight hour, criteria other than those
specified in this paragraph may be used for structural substantiation
to show continued safe flight and landing.
4. Failure indications. For system-failure detection and
indication, the following apply:
a. The system must be checked for failure conditions, not extremely
improbable, that degrade the structural capability below the level
required by part 25, or that significantly reduce the reliability of
the remaining system. As far as reasonably practicable, the flightcrew
must be made aware of these failures before flight. Certain elements of
the control system, such as mechanical and hydraulic components, may
use special periodic inspections, and electronic components may use
daily checks, in lieu of detection and indication systems, to achieve
the objective of this requirement. These certification-maintenance
requirements
[[Page 36326]]
must be limited to components that are not readily detectable by normal
detection-and-indication systems, and where service history shows that
inspections will provide an adequate level of safety.
b. The existence of any failure condition, not extremely
improbable, during flight, that could significantly affect the
structural capability of the airplane, and for which the associated
reduction in airworthiness can be minimized by suitable flight
limitations, must be signaled to the flightcrew. For example, failure
conditions that result in a factor of safety between the airplane
strength and the loads of part 25, subpart C below 1.25, or flutter
margins below V'', must be signaled to the crew during flight.
5. Dispatch with known failure conditions. If the airplane is to be
dispatched in a known system-failure condition that affects structural
performance, or that affects the reliability of the remaining system to
maintain structural performance, then the provisions of these special
conditions must be met, including the provisions of special condition 2
for the dispatched condition, and special condition 3 for subsequent
failures. Expected operational limitations may be taken into account in
establishing Pj as the probability of failure occurrence for
determining the safety margin in Figure 1. Flight limitations and
expected operational limitations may be taken into account in
establishing Qj as the combined probability of being in the
dispatched failure condition and the subsequent failure condition for
the safety margins in Figures 2 and 3. These limitations must be such
that the probability of being in this combined failure state, and then
subsequently encountering limit load conditions, is extremely
improbable. No reduction in these safety margins is allowed if the
subsequent system-failure rate is greater than 10-\3\ per
flight hour.
Issued in Renton, Washington.
Victor Wicklund,
Manager, Transport Standards Branch, Aircraft Certification Service.
[FR Doc. 2017-16416 Filed 8-3-17; 8:45 am]
BILLING CODE 4910-13-P