Special Conditions: Embraer Model EMB-135BJ (Legacy 650) Airplanes, Limit Engine Torque Loads for Sudden Engine Stoppage, 10213-10214 [2011-4072]

Agencies

• Federal Aviation Administration
• DEPARTMENT OF TRANSPORTATION

[Federal Register Volume 76, Number 37 (Thursday, February 24, 2011)]
[Rules and Regulations]
[Pages 10213-10214]
From the Federal Register Online via the Government Printing Office [www.gpo.gov]
[FR Doc No: 2011-4072]



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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 
carl.niedermeyer@faa.gov.

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

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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