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