Special Conditions: Airbus Model A319-151n/171n, A320-251n/271n, and A321-251n/271n (SAneo) Series Airplanes; Transient Engine-Failure Loads, 24193-24195 [2015-10098]

Download as PDF Federal Register / Vol. 80, No. 83 / Thursday, April 30, 2015 / Rules and Regulations impracticable, and good cause exists for adopting these special conditions upon publication in the Federal Register. The FAA is requesting comments to allow interested persons to submit views that may not have been submitted in response to the prior opportunities for comment described above. 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: 14 CFR Part 25 rmajette on DSK2VPTVN1PROD with RULES Design Roll Maneuver Condition In lieu of compliance to § 25.349(a): The following conditions, speeds, and cockpit roll-control motions (except as the motions may be limited by pilot effort) must be considered in combination with an airplane load factor of zero and of two-thirds of the positive maneuvering factor used in design. In determining the resulting control-surface deflections, the torsional flexibility of the wing must be considered in accordance with § 25.301(b): 1. Bombardier Inc. must investigate conditions corresponding to steady rolling velocities. In addition, conditions corresponding to maximum angular acceleration must be investigated for airplanes with engines or other weight concentrations outboard of the fuselage. For the angular acceleration conditions, zero rolling velocity may be assumed in the absence of a rational time-history investigation of the maneuver. 2. At VA, sudden movement of the cockpit roll control up to the limit is assumed. The position of the cockpit roll control must be maintained until a steady roll rate is achieved and then must be returned suddenly to the neutral position. 3. At VC, the cockpit roll control must be moved suddenly and maintained so as to achieve a roll rate not less than that obtained in Special Condition 2, above. 4. At VD, the cockpit roll control must be moved suddenly and maintained so as to achieve a roll rate not less than one third of that obtained in Special Condition 2, above. Jkt 235001 BILLING CODE 4910–13–P Federal Aviation Administration The Special Conditions Accordingly, pursuant to the authority delegated to me by the Administrator, the following special conditions are issued as part of the typecertification basis for the Bombardier Inc. Model BD–700–2A12 and BD–700– 2A13 airplanes. 14:33 Apr 29, 2015 [FR Doc. 2015–10102 Filed 4–29–15; 8:45 am] DEPARTMENT OF TRANSPORTATION Authority: 49 U.S.C. 106(g), 40113, 44701, 44702, 44704. VerDate Sep<11>2014 Issued in Renton, Washington, on April 17, 2015. Victor Wicklund, Acting Manager, Transport Airplane Directorate, Aircraft Certification Service. [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 Federal Aviation Administration (FAA), DOT. ACTION: Final special conditions; request for comments. AGENCY: 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 transportcategory 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. SUMMARY: PO 00000 Frm 00003 Fmt 4700 Sfmt 4700 24193 • 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 E:\FR\FM\30APR1.SGM 30APR1 24194 Federal Register / Vol. 80, No. 83 / Thursday, April 30, 2015 / Rules and Regulations comments. We may change these special conditions based on the comments we receive. rmajette on DSK2VPTVN1PROD with RULES 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 § 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 VerDate Sep<11>2014 14:33 Apr 29, 2015 Jkt 235001 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 § 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 § 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 § 11.38, and they become part of the type certification basis under § 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 § 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 fanblade failures, and these events occur much less frequently than the typical ‘‘limit’’ load condition. To maintain the level of safety envisioned by § 25.361(b), more comprehensive criteria are required for PO 00000 Frm 00004 Fmt 4700 Sfmt 4700 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 enginefailure 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. E:\FR\FM\30APR1.SGM 30APR1 Federal Register / Vol. 80, No. 83 / Thursday, April 30, 2015 / Rules and Regulations DEPARTMENT OF TRANSPORTATION 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 § 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. rmajette on DSK2VPTVN1PROD with RULES The Special Conditions Federal Aviation Administration 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 VerDate Sep<11>2014 14:33 Apr 29, 2015 Jkt 235001 14 CFR Part 39 [Docket No. FAA–2014–0286; Directorate Identifier 2014–NM–004–AD; Amendment 39–18145; AD 2015–08–09] RIN 2120–AA64 Airworthiness Directives; The Boeing Company Airplanes Federal Aviation Administration (FAA), DOT. ACTION: Final rule. AGENCY: 24195 Management Facility between 9 a.m. and 5 p.m., Monday through Friday, except Federal holidays. The AD docket contains this AD, the regulatory evaluation, any comments received, and other information. The address for the Docket Office (phone: 800–647–5527) is Docket Management Facility, U.S. Department of Transportation, Docket Operations, M–30, West Building Ground Floor, Room W12–140, 1200 New Jersey Avenue SE., Washington, DC 20590. FOR FURTHER INFORMATION CONTACT: We are adopting a new airworthiness directive (AD) for certain The Boeing Company Model 737–600 and –700 series airplanes. This AD was prompted by reports of cracking in the body station (STA) 727 bulkhead lower frame. This AD requires a detailed and open hole high frequency eddy current (HFEC) inspection of the left- and rightside lower frame webs and inner chords for cracking, and corrective actions and preventative modifications if necessary. This AD also provides for optional terminating action of the repetitive inspections, under certain conditions. We are issuing this AD to detect and correct cracking in a bulkhead lower frame web and inner chord, which could result in a severed frame and induced skin cracks, and could lead to rapid decompression of the fuselage. DATES: This AD is effective June 4, 2015. The Director of the Federal Register approved the incorporation by reference of a certain publication listed in this AD as of June 4, 2015. ADDRESSES: For service information identified in this AD, contact Boeing Commercial Airplanes, Attention: Data & Services Management, P.O. Box 3707, MC 2H–65, Seattle, WA 98124–2207; telephone 206–544–5000, extension 1; fax 206–766–5680; Internet https:// www.myboeingfleet.com. You may view this referenced service information at the FAA, Transport Airplane Directorate, 1601 Lind Avenue SW., Renton, WA. For information on the availability of this material at the FAA, call 425–227–1221. It is also available on the Internet at http:// www.regulations.gov by searching for and locating Docket No. FAA–2014– 0286. SUMMARY: Alan Pohl, Aerospace Engineer, Airframe Branch, ANM–120S, FAA, Seattle Aircraft Certification Office, 1601 Lind Avenue SW., Renton, WA 98057–3356; phone: 425–917–6450; fax: 425–917–6590; email: alan.pohl@ faa.gov. SUPPLEMENTARY INFORMATION: Discussion We issued a notice of proposed rulemaking (NPRM) to amend 14 CFR part 39 by adding an AD that would apply to certain The Boeing Company Model 737–600 and –700 series airplanes. The NPRM published in the Federal Register on May 28, 2014 (79 FR 30490). The NPRM was prompted by reports of cracking in the body STA 727 bulkhead lower frame. The NPRM proposed to require a detailed and open hole high frequency eddy current (HFEC) inspection of the left- and rightside lower frame webs and inner chords for cracking, as applicable, and corrective actions and preventative modifications if necessary. The NPRM also proposed to provide for an optional terminating action for the repetitive inspections under certain conditions. We are issuing this AD to detect and correct cracking in a bulkhead lower frame web and inner chord, which could result in a severed frame and induced skin cracks, and could lead to rapid decompression of the fuselage. Comments We gave the public the opportunity to participate in developing this AD. Boeing and United Airlines stated that they support the NPRM (79 FR 30490, May 28, 2014). The following presents the comments received on the NPRM, and the FAA’s response to each comment. Examining the AD Docket You may examine the AD docket on the Internet at http:// www.regulations.gov by searching for and locating Docket No. FAA–2014– 0286; or in person at the Docket Request To Clarify Modification and Repair Requirements Southwest Airlines (SWA) requested that we clarify whether the preventative modifications and repairs of the lower frame webs and inner chords (if PO 00000 Frm 00005 Fmt 4700 Sfmt 4700 E:\FR\FM\30APR1.SGM 30APR1

Agencies

[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]


-----------------------------------------------------------------------

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.

-----------------------------------------------------------------------

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