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[Federal Register Volume 80, Number 83 (Thursday, April 30, 2015)]
[Rules and Regulations]
[Pages 24193-24195]
From the Federal Register Online via the Government Publishing Office [www.gpo.gov]
[FR Doc No: 2015-10098]

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DEPARTMENT OF TRANSPORTATION

Federal Aviation Administration

14 CFR Part 25

[Docket No. FAA-2014-1080; Special Conditions No. 25-582-SC]

Special Conditions: Airbus Model A319-151n/171n, A320-251n/271n, 
and A321-251n/271n (SAneo) Series Airplanes; Transient Engine-Failure 
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 Airbus Model A319-
151n/171n, A320-251n/271n, and A321-251n/271n (collectively known as 
Single Aisle new engine option (SA neo)) series airplanes. These 
airplanes will have a novel or unusual design feature when compared to 
the state of technology envisioned in the airworthiness standards for 
transport-category airplanes. This design feature is a new generation 
of high-bypass engines, and the potential loads resulting from extreme 
engine-failure 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: This action is effective on Airbus on April 30, 2015. We must 
receive your comments by June 15, 2015.

ADDRESSES: Send comments identified by docket number FAA-2014-1080 
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 9 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 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: Todd Martin, FAA, ANM-115, Transport 
Airplane Directorate, Aircraft Certification Service, 1601 Lind Avenue 
SW., Renton, Washington 98057-3356; telephone 425-227-1178; facsimile 
425-227-1320.

SUPPLEMENTARY INFORMATION: The FAA has determined that notice of, and 
opportunity for prior public comment on, these special conditions is 
unnecessary.
    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 in the 
Federal Register.

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 by the closing date for

[[Page 24194]]

comments. We may change these special conditions based on the comments 
we receive.

Background

    On February 29, 2012, Airbus applied for amended type certificate 
no. A28NM for their new Model SAneo series airplanes. Later, Airbus 
requested, and the FAA approved, an extension to the application date 
for FAA type certification to June 30, 2012.
    The Airbus Model SAneo series airplanes are derivatives of the 
A319-100, A320-200, and A321-200 series airplanes equipped with 
SharkletsTM (large winglets). The changes include 
installation of new CFMTM LEAPTM A engines on the 
A319-151n, A320-251n, and A321-251n series airplanes, and installation 
of new Pratt & Whitney PW-1100G engines on the A319-171n, A320-271n, 
and A321-271n series airplanes with larger fan diameters and reduced 
fuel consumption as compared to the current engines. The changes also 
include new nacelles, new pylons, new engine mounts, new bleed-air 
systems, structural reinforcements, software changes for the bleed-air 
system, an auto-flight system, an indicating and recording system, 
flight-warning and flight-control computers, and small changes to 
certified weights.
    The existing regulations are inadequate because the new high-bypass 
fan engines of the Airbus Model SAneo series airplanes can cause more 
damage in a failure event than could the previous engines.

Type Certification Basis

    The certification basis for the SAneo series airplanes is the 
certification basis for the A319-100, A320-200 and A321-200 series 
airplanes with Sharklets, as defined in type-certificate data sheet 
A28NM for components or areas not affected by the SAneo change; and 
sections of 14 CFR part 25 as amended by Amendments 25-1 through 25-136 
(i.e., the amendment in effect on the date of the new reference date of 
application, June 30, 2012) applied to the components and areas 
affected by the SAneo change. Under the provisions of Sec.  21.101, 
these regulations will be incorporated into type certificate no. A28NM 
after type certification approval of the Airbus Model SAneo series 
airplanes.
    In addition, the certification basis includes certain special 
conditions, exemptions, or later amended sections of the applicable 
part that are not relevant to these special conditions.
    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 Airbus Model SAneo series airplane 
because of a novel or unusual design feature, special conditions are 
prescribed under 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, these special conditions would also apply to 
the other model under Sec.  21.101.
    In addition to the applicable airworthiness regulations and special 
conditions, the Airbus Model SAneo series 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.
    The FAA issues special conditions, as defined in 14 CFR 11.19, 
under Sec.  11.38, and they become part of the type certification basis 
under Sec.  21.17(a)(2).

Novel or Unusual Design Features

    The Airbus Model SAneo series airplanes will incorporate the 
following novel or unusual design feature:
    Engines with large, high-bypass fans capable of producing much 
higher failure loads than previous engine designs.
    The Airbus Model SAneo series airplanes therefore require 
additional dynamic-load analyses to assess the most severe engine-
failure events. The loads resulting from these conditions would be 
considered as ultimate loads, with an additional safety factor applied 
to the airframe-supporting structure.

Discussion

    The size, configuration, and failure modes of jet engines has 
changed considerably from those envisioned in Sec.  25.361(b), when the 
engine-seizure requirement was first adopted. Engines have become 
larger and are now designed with large, high-bypass fans capable of 
producing much higher failure loads. 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 special conditions for Model SAneo series airplanes and related 
future airplane models. Service history has shown 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.
    To maintain the level of safety envisioned by Sec.  25.361(b), more 
comprehensive criteria are required for the new generation of high-
bypass engines. These special conditions would distinguish between the 
more-common engine-failure event and those rare events resulting from 
structural failures. The more-common events would continue to be 
treated as static torque limit-load conditions. The more-severe events 
resulting from extreme engine-failure conditions (such as loss of a 
full fan blade at redline speed) would be treated as full dynamic-load 
conditions. These would be considered ultimate loads and include all 
transient loads associated with the event. An additional safety factor 
would be applied to the more-critical airframe supporting structure.
    The regulatory authorities and industry 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. These special conditions reflect the ARAC recommendation 
and are essentially harmonized with the corresponding EASA 
Certification Specifications (CS) 25. In addition, the ARAC 
recommendation includes corresponding advisory material that is 
incorporated into CS-25. This advisory material is considered an 
acceptable means of compliance to the 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 apply to the Airbus 
Model SAneo series airplanes. Should Airbus apply later for a change to 
the type certificate to include another model incorporating the same 
novel or unusual design feature, these special conditions would apply 
to that model as well.

Conclusion

    This action affects only certain novel or unusual design features 
on the Airbus Model SAneo series 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:

    Authority: 49 U.S.C. 106(g), 40113, 44701, 44702, 44704.

[[Page 24195]]

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 Airbus Model SAneo series airplanes.
    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 torque limit 
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 installations, the power-unit mounts 
and adjacent supporting airframe structure must be designed to 
withstand 1g level flight loads acting simultaneously with the maximum 
torque limit 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 
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 
Special Conditions 3.a. and 3.b., above, 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. The airplane must be capable of continued safe flight 
considering the aerodynamic effects on controllability due to any 
permanent deformation that results from the conditions specified in 
Special Condition 3, above.

    Issued in Renton, Washington, on April 19, 2015.
Victor Wicklund,
Acting Manager, Transport Airplane Directorate, Aircraft Certification 
Service.
[FR Doc. 2015-10098 Filed 4-29-15; 8:45 am]
 BILLING CODE 4910-13-P
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