[Federal Register Volume 77, Number 186 (Tuesday, September 25, 2012)]
[Proposed Rules]
[Pages 58970-58971]
From the Federal Register Online via the Government Publishing Office [www.gpo.gov]
[FR Doc No: 2012-23536]


 ========================================================================
 Proposed Rules
                                                 Federal Register
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 This section of the FEDERAL REGISTER contains notices to the public of 
 the proposed issuance of rules and regulations. The purpose of these 
 notices is to give interested persons an opportunity to participate in 
 the rule making prior to the adoption of the final rules.
 
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  Federal Register / Vol. 77, No. 186 / Tuesday, September 25, 2012 / 
Proposed Rules  

[[Page 58970]]



DEPARTMENT OF TRANSPORTATION

Federal Aviation Administration

14 CFR Part 25

[Docket No. FAA-2012-0260; Notice No. 25-12-05-SC]


Special Conditions: Embraer S.A. Model EMB-550 Airplanes, Sudden 
Engine Stoppage

AGENCY: Federal Aviation Administration (FAA), DOT.

ACTION: Notice of proposed special conditions.

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SUMMARY: This action proposes special conditions for the Embraer Model 
EMB-550 airplane. This airplane will have a novel or unusual design 
feature associated with the effects of sudden engine stoppage upon the 
airframe. The applicable airworthiness regulations do not contain 
adequate or appropriate safety standards for this design feature. 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.

DATES: Submit your comments on or before October 26, 2012.

ADDRESSES: Send comments identified by docket number FAA-2011-0260 
using any of the following methods:
     Federal eRegulations Portal: Go to http://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 8 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 http://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), as well as at http://DocketsInfo.dot.gov/ gov/.
    Docket: Background documents or comments received may be read at 
http://www.regulations.gov/ at any time. Follow the online instructions 
for accessing the docket or go to the 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: Cindy Ashforth, FAA, International 
Branch, ANM-116, Transport Airplane Directorate, Aircraft Certification 
Service, 1601 Lind Avenue SW., Renton, Washington 98057-3356; telephone 
(425) 227-2768; facsimile (425) 227-1320.

SUPPLEMENTARY INFORMATION: 

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 on or before the closing 
date for comments. We may change these special conditions based on the 
comments we receive.

Background

    On May 14, 2009, Embraer applied for a type certificate for their 
new Model EMB-550 airplane. The Model EMB-550 airplane is the first of 
a new family of jets designed as a corporate jet, and for fractional, 
charter, and private-owner operations. The airplane is a conventional 
configuration with a low wing and T-tail empennage. The primary 
structure is metal with composite empennage and control surfaces. The 
Model EMB-550 airplane is designed for eight passengers, with a maximum 
of 12 passengers (including toilet seat). It is equipped with two 
Honeywell HTF7500-E medium-bypass-ratio turbofan jet engines mounted on 
aft-fuselage pylons. Each engine produces approximately 6,540 lb of 
thrust for normal takeoff. The primary flight-control systems are 
electronically controlled using fly-by-wire (FBW) technology.
    The Model EMB-550 airplane incorporates novel or unusual design 
features involving engine size and torque load that affect the airframe 
as it relates to sudden engine-stoppage conditions.

Type Certification Basis

    Under the provisions of Title 14, Code of Federal Regulations (14 
CFR) 21.17, Embraer must show that the Model EMB-550 airplane meets the 
applicable provisions of part 25, as amended by Amendments 25-1 through 
1-127.
    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-550 airplane 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, the special conditions would also apply to the 
other model.
    In addition to the applicable airworthiness regulations and special 
conditions, the Model EMB-550 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; and the FAA must issue a 
finding of regulatory adequacy under Sec.  611 of Public Law 92-574, 
the ``Noise Control Act of 1972.''
    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.  21.17(a)(2).

[[Page 58971]]

Novel or Unusual Design Features

    The Model EMB-550 airplane will incorporate the following novel or 
unusual design features:
    The engine proposed for the Embraer Model EMB-550 airplane is a 
medium-bypass-ratio turbofan jet engine that will not seize and produce 
transient torque loads in the same manner that is envisioned by current 
Sec.  25.361(b)(1) related to ``sudden engine stoppage.''

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. In the past, the design torque loads associated with typical 
failure scenarios have been estimated by the engine manufacturer and 
provided to the airframe manufacturer as limit loads. These limit loads 
were considered simple, purely static torque loads. The size, 
configuration, and failure modes of jet engines have changed 
considerably from what was 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.
    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 
generations of jet engines are 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 Embraer Model EMB-550 airplane.
    To maintain the level of safety envisioned in Sec.  25.361(b), more 
comprehensive criteria are needed for the new generation of high-bypass 
engines. The special conditions would distinguish between the more 
common engine-failure events and those rare events resulting from 
structural failures. For these less common but more severe seizure 
events, the criteria (as stated in special conditions numbers 3 and 4, 
below) could allow some deformation in the engine-supporting structure 
(ultimate load design) 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 
purely 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-550 airplane. Should Embraer apply at a later date for a 
change to the type certificate to include another model incorporating 
the same novel or unusual design feature, the special conditions would 
apply to that model as well.

Conclusion

    This action affects only certain novel or unusual design features 
on one model of 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, the Federal Aviation Administration (FAA) proposes the 
following special conditions as part of the type-certification basis 
for the Embraer Model EMB-550 airplane. In lieu of 14 CFR 25.361(b), 
the following special conditions are proposed:
    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 that could 
result in a temporary loss of power or thrust, and
    (b) The maximum acceleration of the engine.
    2. For auxiliary power unit (APU) installations, the APU 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 APU deceleration due to malfunction or structural 
failure; and
    (b) The maximum acceleration of the APU.
    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 
separately
    (b) Where applicable to a specific engine design, any other engine 
structural failure that results in higher loads.
    4. The ultimate loads developed from the conditions specified in 
paragraphs 3(a) and 3(b) 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 3, above, must not prevent continued 
safe flight and landing.

    Issued in Renton, Washington, on September 6, 2012.
Ali Bahrami,
Manager, Transport Airplane Directorate, Aircraft Certification 
Service.
[FR Doc. 2012-23536 Filed 9-24-12; 8:45 am]
BILLING CODE 4910-13-P