[Federal Register Volume 76, Number 37 (Thursday, February 24, 2011)]
[Rules and Regulations]
[Pages 10213-10214]
From the Federal Register Online via the Government Publishing Office [www.gpo.gov]
[FR Doc No: 2011-4072]
[[Page 10213]]
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DEPARTMENT OF TRANSPORTATION
Federal Aviation Administration
14 CFR Part 25
[Docket No. NM449; Notice No. 25-420-SC]
Special Conditions: Embraer Model EMB-135BJ (Legacy 650)
Airplanes, Limit Engine Torque Loads for Sudden Engine Stoppage
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 Embraer Model EMB-
135BJ (Legacy 650) airplanes, modified in accordance with design-change
application (DCA) 0145-000-00020-2008/FAA (the most current FAA-
approved revision; hereafter referred to as ``the DCA''). This Model
EMB-135BJ airplane, as modified by the DCA, is commonly referred to as
the Legacy 650 airplane. It will have a novel or unusual design feature
associated with engine size and the potential torque load imposed by
sudden engine-stoppage conditions. 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: The effective date of these special conditions is February 17,
2011. We must receive your comments by April 11, 2011.
ADDRESSES: You must mail two copies of your comments to: Federal
Aviation Administration, Transport Airplane Directorate, Attn: Rules
Docket (ANM-113), Docket No. NM449, 1601 Lind Avenue, SW., Renton,
Washington 98057-3356. You may deliver two copies to the Transport
Airplane Directorate at the above address. You must mark your comments:
Docket No. NM449. You can inspect comments in the Rules Docket
weekdays, except Federal holidays, between 7:30 a.m. and 4 p.m.
FOR FURTHER INFORMATION CONTACT: Carl Niedermeyer, FAA Airframe Branch,
ANM-115, Transport Airplane Directorate, Aircraft Certification
Service, 1601 Lind Avenue, SW., Renton, Washington 98057-3356;
telephone (425) 227-2279; facsimile (425) 227-1149; e-mail
[email protected].
SUPPLEMENTARY INFORMATION: The FAA has determined that notice of, and
opportunity for prior public comment on, these special conditions are
impracticable because these procedures would significantly delay
issuance of the design approval and thus delivery of the affected
aircraft. 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 that
good cause exists for making these special conditions effective upon
issuance.
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 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 special conditions. You can inspect the docket 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 preamble
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
these special conditions based on the comments we receive.
If you want us to acknowledge receipt of your comments on these
special conditions, include with your comments a self-addressed,
stamped postcard on which you have written the docket number. We will
stamp the date on the postcard and mail it back to you.
Background
On September 19, 2008, Embraer applied for an amendment to U.S.
type certificate (TC) T00011AT to include the new certification basis
of Model EMB-135BJ (Legacy 650), modified according to major level 1
design change documented in DCA 0145-000-00020-2008/FAA Revision
original. This airplane is a derivative of the Model EMB-135BJ (Legacy
600) airplane, which is approved under the same TC.
The Model EMB-135BJ (Legacy 650) airplane, modified according to
the DCA, is powered by two Rolls Royce Allison engines, model AE3007A2.
The airplane has an interior seating arrangement similar to the
baseline configuration Model EMB-135BJ (Legacy 600) airplane, with
increased maximum takeoff weight (MTOW) of 24,300 kg. It is intended
for long-range operations with enhanced performance, and has additional
fuel capacity over the Model EMB-135BJ (Legacy 600) baseline
configuration.
Type Certification Basis
Under the provisions of Title 14, Code of Federal Regulations (14
CFR), 21.17, Embraer must show that the Model EMB-135BJ (Legacy 650)
airplane meets the applicable provisions of the regulations
incorporated by reference in TC T00011AT or the applicable regulations
in effect on the date of application for the change to the TC data
sheet. The regulations incorporated by reference in the type
certificate are commonly referred to as the ``original type-
certification basis.'' The regulations incorporated by reference in TC
T00011AT are 14 CFR part 25 effective February 1, 1965, including
Amendments 25-1 through 25-85, and 25-86 (applicable for Sec.
25.1517), 25-88, 25-90, 25-91 (applicable for Sec. Sec. 25.331,
25.335(b)(2), 25.351, 25.363, 25.371, 25.415, 25.491, 25.499 and
25.561), 25-93, 25-94 (applicable for Sec. 25.807), 25-96 (applicable
for Sec. 25.571(e)(1)), 25-97, and 25-98, with certain exceptions that
are not relevant to this special condition.
In addition, if the regulations incorporated by reference do not
provide adequate standards with respect to the change, the applicant
must comply with certain regulations in effect on the date of
application for the change. The FAA has determined that the Model EMB-
135BJ (Legacy 650) airplane must be shown to comply with the
airworthiness standards of part 25, including Amendments 25-1 through
25-124, for components, areas, appliances, and systems affected by the
type design change presented in the DCA.
If the Administrator finds that the applicable airworthiness
regulations (i.e., 14 CFR part 25) do not contain adequate or
appropriate safety standards for the Model EMB-135BJ (Legacy 650)
airplane because of a novel or unusual design feature, special
conditions are prescribed under the provisions of 14 CFR 21.16.
In addition to the applicable airworthiness regulations and special
conditions, this Model EMB-135BJ (Legacy 650) airplane must comply with
the fuel-vent and exhaust-emission requirements of 14 CFR part 34 and
the
[[Page 10214]]
noise certification requirements of 14 CFR part 36.
Special conditions, as defined in 14 CFR 11.19, are issued
according to Sec. 11.38 and become part of the type-certification
basis according to 14 CFR 21.101(b)(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, or should any other model already included on
the same type certificate be modified to incorporate 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(a)(1).
Novel or Unusual Design Features
The Model EMB-135BJ (Legacy 650) airplane will incorporate novel or
unusual design features involving engine size and the potential torque
load imposed by sudden-engine-stoppage conditions.
Discussion
The limit engine-torque load imposed by sudden engine stoppage, due
to malfunction or structural failure (such as compressor jamming), has
been a specific requirement for transport-category airplanes since
1957. The size, configuration, and failure modes of jet engines have
changed considerably from those envisioned when the engine seizure
requirement of Sec. 25.361(b) was first adopted. Current engines are
much larger and are now designed with large bypass fans capable of
producing much larger torque loads if they become jammed. It is evident
from service history that the frequency of occurrence of the most
severe sudden-engine-stoppage events is rare.
Relative to the engine configurations that existed when the rule
was developed in 1957, the present generation of engines are
sufficiently different and novel to justify issuance of special
conditions to establish appropriate design standards. The latest
generation of jet engines is capable of producing, during failure,
transient loads that are significantly higher and more complex than the
generation of engines that were present when the existing standard was
developed. Therefore, the FAA has determined that special conditions
are needed for the Model EMB-135BJ (Legacy 650) airplanes.
To maintain the level of safety intended in Sec. 25.361(b), a more
comprehensive criteria is needed for the new generation of high-bypass
engines. These special conditions would distinguish between the more-
common seizure events and those less-common seizure events resulting
from structural failures. For those less-common but severe seizure
events, these criteria could allow some deformation in the engine-
supporting structure (ultimate load design) in order to absorb the
higher energy associated with the high-bypass engines, while at the
same time protecting the adjacent primary structure in the wing and
fuselage by providing a higher safety factor. The criteria for the
more-severe events would no longer be a pure static torque-load
condition, but would account for the full spectrum of transient dynamic
loads developed from the engine-failure condition.
Applicability
As discussed above, these special conditions are applicable to the
Model EMB-135BJ (Legacy 650) airplanes. Should Embraer apply at a later
date for a change to the type design of a certified airplane without
new model designation on Type Certificate No. T00011AT to incorporate
the same novel or unusual design feature, the special conditions would
apply to that model as well under the provisions of Sec. 21.101(a)(1).
Certification of the Model EMB-135BJ (Legacy 650) airplane is
currently scheduled for February 18, 2011. The substance of these
special conditions has been subject to the notice and public-comment
procedure in several prior instances. Therefore, because a delay would
significantly affect the applicant's both installation of the system
and certification of the airplane, these special conditions are
effective upon issuance.
Conclusion
This action affects only certain novel or unusual design features
on Model EMB-135BJ airplanes. It is not a rule of general applicability
and it affects only the applicant who applied to the FAA for approval
of these features on the airplane.
Under standard practice, the effective date of final special
conditions would be 30 days after the date of publication in the
Federal Register; however, as the certification date for the Embraer
Model EMB-135BJ (Legacy 650) airplane is imminent, the FAA finds that
good cause exists to make these special conditions effective upon
issuance.
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 the Embraer Model EMB-135BJ (Legacy
650) airplanes.
1. For turbine engine installations, the engine mounts, pylons and
adjacent supporting airframe structure must be designed to withstand 1g
level flight loads acting simultaneously with the maximum limit torque
loads imposed by each of the following:
a. Sudden engine deceleration due to a malfunction, which could
result in a temporary loss of power or thrust; and
b. The maximum acceleration of the engine.
2. For auxiliary-power-unit installations, the power-unit mounts
and adjacent supporting airframe structure must be designed to
withstand 1g level flight loads acting simultaneously with the maximum
limit torque loads imposed by each of the following:
a. Sudden auxiliary-power-unit deceleration due to malfunction or
structural failure; and
b. The maximum acceleration of the power unit.
3. For engine supporting structure, an ultimate loading condition
must be considered that combines 1g flight loads with the transient
dynamic loads resulting from:
a. The loss of any fan, compressor, or turbine blade; and
b. Separately, where applicable to a specific engine design, any
other engine structural failure that results in higher loads.
4. The ultimate loads developed from these conditions are to be
multiplied by a factor of 1.0 when applied to engine mounts and pylons
and multiplied by a factor of 1.25 when applied to adjacent supporting
airframe structure.
5. Any permanent deformation that results from the conditions
specified in Special Condition number 3 must not prevent continued safe
flight and landing.
Issued in Renton, Washington, on February 17, 2011.
Ali Bahrami,
Manager, Transport Airplane Directorate, Aircraft Certification
Service.
[FR Doc. 2011-4072 Filed 2-23-11; 8:45 am]
BILLING CODE 4910-13-P