Discussion
We issued a notice of proposed rulemaking (NPRM) to amend 14 CFR part 39 by adding an AD that would apply to certain Airbus Model A318 series airplanes and Model A319 series airplanes; all Model A320-211, - 212, -214, -216, -231, -232, and -233 airplanes; and all Model A321- 111, -112, -131, -211, -212, -213, -231, and -232 airplanes. The NPRM published in the Federal Register on January 12, 2018 (83 FR 1579) (``the NPRM''). The NPRM was prompted by an evaluation by the DAH indicating that the holes of the upper cleat to upper stringer attachments at certain areas of the left- and right-hand wings are subject to WFD. The NPRM proposed to require modifying the holes of the upper cleat to upper stringer attachments at certain areas of the left- and right-hand wings. We are issuing this AD to prevent fatigue cracking in the stringer attachment holes of the wings, which could result in reduced structural integrity of the wings.
The European Aviation Safety Agency (EASA), which is the Technical Agent for the Member States of the European Union, has issued EASA AD 2017-0117, dated July 7, 2017 (referred to after this as the Mandatory Continuing Airworthiness Information, or ``the MCAI''), to correct an unsafe condition for certain Airbus Model A318 series airplanes and Model A319 series
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airplanes; all Model A320-211, -212, -214, -216, -231, -232, and -233 airplanes; and all Model A321-111, -112, -131, -211, -212, -213, -231, and -232 airplanes. The MCAI states:
Within the scope of work of service life extension for A320 aeroplanes and of widespread fatigue damage evaluations, it has been determined that a structural modification is required to allow the aeroplanes to continue operation up to the limit of validity (LoV).
This condition, if not corrected, may affect the structural integrity of the wing.
To address this potential unsafe condition, Airbus issued [service bulletin] SB A320-57-1208, providing instructions to oversize the holes of the upper cleat to upper stringer attachments at Rib 2 to Rib 7 (inclusive).
For the reason described above, this [EASA] AD requires modification of the affected holes.
You may examine the MCAI in the AD docket on the internet at http://www.regulations.gov by searching for and locating Docket No. FAA-2017- 1245.
Comments
We gave the public the opportunity to participate in developing this AD. The following presents the comments received on the NPRM and the FAA's response to each comment. United Airlines agreed with the intent of the NPRM.
Request To Clarify Applicability
Allegiant Air asked that we clarify the manufacturer serial numbers (MSNs) identified in the applicability section of the proposed AD. Allegiant Air stated that the effectivity specified in Airbus Service Bulletin A320-57-1208, dated November 21, 2016, identifies airplanes up to and including MSN 7493, and asked about airplanes having MSNs higher than 7493. Allegiant Air noted that it has 11 Model A320 airplanes with MSNs outside those listed in Airbus Service Bulletin A320-57-1208, dated November 21, 2016. Allegiant Air added that it understands the AD takes precedence over the service information, but there are several configurations listed therein. Allegiant Air also added that since the MSNs in question are not listed in the effectivity of the service information, an operator with an MSN outside the effectivity will not know which modification kit to order.
We agree to clarify. The effectivity in Airbus Service Bulletin A320-57-1208, dated November 21, 2016, does not include all MSNs for Model A320 airplanes, and the applicability specified in paragraph (c) of this AD includes all MSNs for Model A320 airplanes, except for airplanes having certain modifications. We acknowledge that the referenced service information may not be adequate for certain airplane configurations. Therefore, we have revised paragraph (g) of this AD to provide an option for doing the modification, including identification of the appropriate modification kit, using a method approved by the Manager, International Section, Transport Standards Branch, FAA; or EASA; or Airbus's EASA Design Organization Approval (DOA).
In addition, Airbus has informed us that Revision 1 of the referenced service information will expand the effectivity to include MSNs up to 8555. Airbus has also informed us that, upon request, it will issue a technical adaptation as an interim method of compliance until a revised service bulletin is issued.
Conclusion
We reviewed the relevant data, considered the comments received, and determined that air safety and the public interest require adopting this AD as proposed except for minor editorial changes. We have determined that these minor changes:
Are consistent with the intent that was proposed in the NPRM for correcting the unsafe condition; and
Do not add any additional burdenupon the public than was already proposed in the NPRM.
Related Service Information Under 1 CFR Part 51
Airbus has issued Airbus Service Bulletin A320-57-1208, dated November 21, 2016. This service information describes procedures for modifying the stringer attachments at rib 2 through rib 7 of the left- and right-hand wings. The modification includes oversizing the holes, doing an eddy current inspection of the affected holes for damage, and repair. This service information is reasonably available because the interested parties have access to it through their normal course of business or by the means identified in the ADDRESSES section.
Costs of Compliance
We estimate that this AD affects 1,136 airplanes of U.S. registry.
We estimate the following costs to comply with this AD:
Estimated Costs ----------------------------------------------------------------------------------------------------------------
Cost per Cost on U.S.
ActionLabor cost Parts cost product operators ---------------------------------------------------------------------------------------------------------------- Modification (by oversizing and 125 work-hours x $85 per $26,260 $36,885 $41,901,360
doing eddy current inspection). hour = $10,625. ----------------------------------------------------------------------------------------------------------------
We have received no definitive data that would enable us to provide cost estimates for the on-condition actions specified in this AD.
Authority for This Rulemaking
Title 49 of the United States Code specifies the FAA's authority to issue rules on aviation safety. Subtitle I, section 106, describes the authority of the FAA Administrator. Subtitle VII: Aviation Programs, describes in more detail the scope of the Agency's authority.
We are issuing this rulemaking under the authority described in Subtitle VII, Part A, Subpart III, Section 44701: ``General requirements.'' Under that section, Congress charges the FAA with promoting safe flight of civil aircraft in air commerce by prescribing regulations for practices, methods, and procedures the Administrator finds necessary for safety in air commerce. This regulation is within the scope of that authority because it addresses an unsafe condition that is likely to exist or develop on products identified in this rulemaking action.
This AD is issued in accordance with authority delegated by the Executive Director, Aircraft Certification Service, as authorized by FAA Order 8000.51C. In accordance with that order, issuance of ADs is normally a function of the Compliance and Airworthiness Division, but during this transition period, the Executive Director has delegated the authority to issue ADs applicable to transport category airplanes to the Director of the System Oversight Division.
Regulatory Findings
We determined that this AD will not have federalism implications under Executive Order 13132. This AD will not have a substantial direct effect on
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the States, on the relationship between the national government and the States, or on the distribution of power and responsibilities among the various levels of government.
For the reasons discussed above, I certify that this AD:
1. Is not a ``significant regulatory action'' under Executive Order 12866,
2. Is not a ``significant rule'' under the DOT Regulatory Policies and Procedures (44 FR 11034, February 26, 1979),
3. Will not affect intrastate aviation in Alaska, and
4. Will not have a significant economic impact, positive or negative, on a substantial number of small entities under the criteria of the Regulatory Flexibility Act.
List of Subjects in 14 CFR Part 39
Air transportation, Aircraft, Aviation safety, Incorporation by reference, Safety.