Source: https://www.federalregister.gov/documents/2015/04/30/2015-10098/special-conditions-airbus-model-a319-151n171n-a320-251n271n-and-a321-251n271n-saneo-series-airplanes
Timestamp: 2018-04-20 11:56:59
Document Index: 238570007

Matched Legal Cases: ['art 25', '§\u200921', 'art 25', '§\u200921', 'art 34', 'art 36', '§\u200925', '§\u200925']

Federal Register :: Special Conditions: Airbus Model A319-151n/171n, A320-251n/271n, and A321-251n/271n (SAneo) Series Airplanes; Transient Engine-Failure Loads
This action is effective on Airbus on April 30, 2015. We must receive your comments by June 15, 2015.
Docket No. FAA-2014-1080
Special Conditions No. 25-582-SC
FAA-2014-1080
https://www.federalregister.gov/d/2015-10098 https://www.federalregister.gov/d/2015-10098
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.
Send comments identified by docket number FAA-2014-1080 using any of the following methods:
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.
The FAA has determined that notice of, and opportunity for prior public comment on, these special conditions is unnecessary.
We will consider all comments we receive by the closing date for Start Printed Page 24194comments. We may change these special conditions based on the comments we receive.
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.
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.
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 § 21.16.
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 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.
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 fan-blade 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 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.
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.
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.
Authority: 49 U.S.C. 106(g), 40113, 44701, 44702, 44704.Start Printed Page 24195
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.
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
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
a. The loss of any fan, compressor, or turbine blade; and separately,
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.
[FR Doc. 2015-10098 Filed 4-29-15; 8:45 am]