Federal Register, Volume 80 Issue 83 (Thursday, April 30, 2015)

[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
Sharklets^TM (large winglets). The changes include
installation of new CFM^TM LEAP^TM 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