
[Federal Register Volume 79, Number 115 (Monday, June 16, 2014)]
[Rules and Regulations]
[Pages 34215-34217]
From the Federal Register Online via the Government Printing Office [www.gpo.gov]
[FR Doc No: 2014-13923]


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DEPARTMENT OF TRANSPORTATION

Federal Aviation Administration

14 CFR Part 25

[Docket No.FAA-2014-0380; Notice No. 25-555-SC]


Special Conditions: Bombardier Aerospace, Models BD-500-1A10 and 
BD-500-1A11; Limit Engine Torque Loads

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 Bombardier 
Aerospace Models BD-500-1A10 and BD-500-1A11 airplanes. These airplanes 
have novel or unusual design features as compared to the state of 
technology envisioned in the airworthiness standards for transport 
category airplanes. These design features include engine size and the 
potential torque loads imposed by sudden engine stoppage. 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 June 16, 2014. 
We must receive your comments by July 31, 2014.

ADDRESSES: Send comments identified by docket number [FAA-2014-0380] 
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

[[Page 34216]]

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/.
    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: Mark Freisthler, FAA, Airframe and 
Cabin Safety Branch, ANM-115, Transport Airplane Directorate, Aircraft 
Certification Service, 1601 Lind Avenue SW., Renton, Washington 98057-
3356; telephone 425-227-1119; facsimile 425-227-1232.

SUPPLEMENTARY INFORMATION: 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 publication.

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 December 10, 2009, Bombardier Aerospace applied for a type 
certificate for their new Models BD-500-1A10 and BD-500-1A11 series 
airplanes (hereafter collectively referred to as ``CSeries''). The 
CSeries airplanes are swept-wing monoplanes with an aluminum alloy 
fuselage sized for 5-abreast seating. Passenger capacity is designated 
as 110 for the Model BD-500-1A10 and 125 for the Model BD-500-1A11. 
Maximum takeoff weight is 131,000 pounds for the Model BD-500-1A10 and 
144,000 pounds for the Model BD-500-1A11.

Type Certification Basis

    Under the provisions of Title 14, Code of Federal Regulations (14 
CFR) 21.17, Bombardier Aerospace must show that the CSeries airplanes 
meet the applicable provisions of part 25, as amended by Amendments 25-
1 through 25-129 thereto.
    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 CSeries 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 or similar 
novel or unusual design feature, the special conditions would also 
apply to the other model under Sec.  21.101.
    In addition to the applicable airworthiness regulations and special 
conditions, the CSeries 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, 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).

Novel or Unusual Design Features

    The CSeries airplanes will incorporate the following novel or 
unusual design features:
    The size, configuration, and failure modes of jet engines have 
changed considerably from those envisioned by 14 CFR 25.361(b) when the 
engine seizure requirement was first adopted. Engines have become 
larger and are now designed with large bypass fans capable of producing 
much larger and more complex dynamic loads. Relative to the engine 
configurations that existed when the rule was developed in 1957, the 
present generation of engines are sufficiently novel or unusual to 
justify issuance of special conditions to establish appropriate design 
standards for the CSeries airplanes.

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, pure torque static loads.
    It is evident from service history that the engine failure events 
that tend to cause the most severe loads are fan blade failures, and 
these events occur much less frequently than the typical ``limit'' load 
condition.
    The regulatory authorities and industry have developed a 
standardized requirement in the Aviation Rulemaking Advisory Committee 
(ARAC) forum. The technical aspects of this requirement have been 
agreed upon and have been accepted by the ARAC Loads and Dynamics 
Harmonization Working Group. The special conditions outlined below 
reflect the ARAC recommendation. The ARAC recommendation includes 
corresponding advisory material, which is considered an acceptable 
means of compliance to these special conditions.
    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 the 
Model BD-500-1A10 and BD-500-1A11 (CSeries) airplanes. Should 
Bombardier Aerospace 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 two model series of airplanes. 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:


[[Page 34217]]


    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 Bombardier Aerospace Model BD-500-1A10 
and BD-500-1A11 (CSeries) airplanes.

Limit Engine Torque Loads

    In lieu of Sec.  25.361(b) the following special conditions apply:
    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 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 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) of these special 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 paragraph 3 must not prevent continued safe flight and 
landing.

    Issued in Renton, Washington, on June 6, 2014.
Jeffrey E. Duven,
Manager, Transport Airplane Directorate, Aircraft Certification 
Service.
[FR Doc. 2014-13923 Filed 6-13-14; 8:45 am]
BILLING CODE 4910-13-P


