AD 2018-17-24

We are adopting a new airworthiness directive (AD) for certain Airbus SAS Model A350-941 airplanes. This AD was prompted by the discovery of inadequate corrosion protection in certain areas of the horizontal stabilizer and the rear fuselage cone structure. This AD requires application of sealant and protective treatment on the affected areas of the horizontal stabilizer and the rear fuselage cone structure and, for certain airplanes, modification of the trimmable horizontal stabilizer (THS) torsion box and re-identification of the elevator. We are issuing this AD to address the unsafe condition on these products.

Final rule.

Adoption of the Amendment

Accordingly, under the authority delegated to me by the Administrator, the FAA amends 14 CFR part 39 as follows:

PART 39--AIRWORTHINESS DIRECTIVES

0 1. The authority citation for part 39 continues to read as follows:

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

Sec. 39.13 [Amended]

0 2. The FAA amends Sec. 39.13 by adding the following new airworthiness directive (AD):

2018-17-24 Airbus SAS: Amendment 39-19378; Docket No. FAA-2018-0506; Product Identifier 2018-NM-045-AD.

(a) Effective Date

This AD is effective October 18, 2018.

(b) Affected ADs

None.

(c) Applicability

This AD applies to Airbus SAS Model A350-941 airplanes certificated in any category, all manufacturer serial numbers, except those on which Airbus Modification 106695 (or retrofit Modification 110281) and Modification 107824 (or retrofit Modification 107877 and retrofit Modification 108494) have been embodied in production.

(d) Subject

Air Transport Association (ATA) of America Code 53, Fuselage; 55, Stabilizers.

(e) Reason

This AD was prompted by the discovery of inadequate corrosion protection in certain areas of the horizontal stabilizer and the rear fuselage cone structure. We are issuing this AD to prevent reduced structural integrity of the horizontal stabilizer and the rear fuselage cone structure.

(f) Compliance

Comply with this AD within the compliance times specified, unless already done.

(g) Definitions

(1) For the purpose of this AD, Group 1 airplanes are those with manufacturer serial numbers (MSNs) listed in Section 1.A., ``Applicability'' of Airbus Service Bulletin A350-53-P029, dated November 17, 2017.
(2) For the purpose of this AD, Group 2 airplanes are those with MSNs listed in Section 1.A., ``Applicability'' of Airbus Service Bulletin A350-55-P003, dated November 6, 2017.

(h) Modification

(1) For Group 1 airplanes: Before exceeding 36 months since the date of issuance of the original standard airworthiness certificate or date of issuance of the original export certificate of airworthiness, or within 90 days after the effective date of this AD, whichever occurs later, apply sealant and protective treatment on the affected areas of the rear fuselage cone structure, as defined in, and in accordance with the Accomplishment Instructions of Airbus Service Bulletin A350-53-P029, dated November 17, 2017.
(2) For Group 2 airplanes: Before exceeding 36 months since the date of issuance of the original standard airworthiness certificate or date of issuance of the original export certificate of airworthiness, or within 90 days after the effective date of this AD, whichever occurs later, accomplish concurrently the actions specified in paragraphs (h)(2)(i) and (h)(2)(ii) of this AD, in accordance with the Accomplishment Instructions of Airbus Service Bulletin A350-55-P003, dated November 6,2017.
(i) Apply sealant and protective treatment on the affected areas of the horizontal stabilizer, as defined in Airbus Service Bulletin A350-55-P003, dated November 6, 2017.
(ii) Modify the trimmable horizontal stabilizer (THS) torsion box in zone 330 and 340, and re-identify the elevator in zone 335 and 345.

(i) Other FAA AD Provisions

The following provisions also apply to this AD:
(1) Alternative Methods of Compliance (AMOCs): The Manager, International Section, Transport Standards Branch, FAA, has the authority to approve AMOCs for this AD, if requested using the procedures found in 14 CFR 39.19. In accordance with 14 CFR 39.19, send your request to your principal inspector or local Flight Standards District Office, as appropriate. If sending information directly to the International Section, send it to the attention of the person identified in paragraph (j)(2) of this AD. Information may be emailed to: 9-ANM-116-AMOC-REQUESTS@faa.gov. Before using any approved AMOC, notify your appropriate principal inspector, or lacking a principal inspector, the manager of the local flight standards district office/certificate holding district office.
(2) Contacting the Manufacturer: For any requirement in this AD to obtain corrective actions from a manufacturer, the action must be accomplished using a method approved by the Manager, International Section, Transport Standards Branch, FAA; or the European Aviation Safety Agency (EASA); or Airbus SAS's EASA Design Organization Approval (DOA). If approved by the DOA, the approval must include the DOA-authorized signature.
(3) Required for Compliance (RC): If any service information contains procedures or tests that are identified as RC, those procedures and tests must be done to comply with this AD; any procedures or tests that are not identified as RC are recommended. Those procedures and tests that are not identified as RC may be deviated from using accepted methods in accordance with the operator's maintenance or inspection program without obtaining approval of an AMOC, provided the procedures and tests identified as RC can be done and the airplane can be put back in an airworthy condition. Any substitutions or changes to procedures or tests identified as RC require approval of an AMOC.

(j) Related Information

(1) Refer to Mandatory Continuing Airworthiness Information (MCAI) EASA AD 2018-0036, dated February 7, 2018, for related information. This MCAI may be found in the AD docket on the internet at http://www.regulations.gov by searching for and locating Docket No. FAA-2018-0506.
(2) For more information about this AD, contact Kathleen Arrigotti, Aerospace Engineer, International Section, Transport Standards Branch, FAA, 2200 South 216th St., Des Moines, WA 98198; telephone and fax 206-231-3218.

(k) Material Incorporated by Reference

(1) The Director of the Federal Register approved the incorporation by reference (IBR) of the service information listed in this paragraph under 5 U.S.C. 552(a) and 1 CFR part 51.
(2) You must use this service information as applicable to do the actions required by this AD, unless this AD specifies otherwise.
(i) Airbus Service Bulletin A350-53-P029, dated November 17, 2017.
(ii) Airbus Service Bulletin A350-55-P003, dated November 6, 2017.
(3) For service information identified in this AD, contact Airbus SAS, Airworthiness Office--EAL, Rond-Point Emile Dewoitine No: 2, 31700 Blagnac Cedex, France; telephone +33 5 61 93 36 96; fax +33 5 61 93 45 80; email continued-airworthiness.a350@airbus.com; internet http://www.airbus.com.
(4) You may view this service information at the FAA, Transport Standards Branch, 2200 South 216th St., Des Moines, WA. For information on the availability of this material at the FAA, call 206-231-3195.
(5) You may view this service information that is incorporated by reference at the National Archives and Records Administration (NARA). For information on the availability of this material at NARA, call 202-741-6030, or go to: http://www.archives.gov/federal-register/cfr/ibr-locations.html.

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 SAS Model A350-941 airplanes. The NPRM published in the Federal Register on June 11, 2018 (83 FR 26882). The NPRM was prompted by the discovery of inadequate corrosion protection in certain areas of the horizontal stabilizer and the rear fuselage cone structure. The NPRM proposed to require application of sealant and protective treatment on the affected areas of the horizontal stabilizer and the rear fuselage cone structure and, for certain airplanes, modification of the THS torsion box and re- identification of the elevator.
We are issuing this AD to address reduced structural integrity of the horizontal stabilizer and the rear fuselage cone structure.
The European Aviation Safety Agency (EASA), which is the Technical Agent for the Member States of the European Union, has issued EASA AD 2018-0036, dated February 7, 2018 (referred to after this as the Mandatory Continuing Airworthiness Information, or ``the MCAI''), to correct an unsafe condition for certain Airbus SAS Model A350-941 airplanes. The MCAI states:

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In some areas of the Horizontal Tail Plane (HTP) [horizontal stabilizer] and fuselage Section (S) 19 [rear fuselage cone structure], the interfay sealant for multimaterial joints (hybrid joints) was only applied on the surface in direct contact with aluminium parts and not between all surfaces of the joint parts. This situation does not ensure full barrier properties. To avoid any risk of water ingress in multi-material-stacks involving aluminium, it is necessary to apply interfay sealant between all assembled parts, even between parts made of corrosion resistant material. This ensures a double barrier in the joint and prevents subsequent potential galvanic corrosion on the aluminum holes on top of the single barrier already applied in aluminium parts.
This condition, if not corrected, could reduce the structural integrity of the HTP and fuselage at S19.
To address this unsafe condition, Airbus developed production mod [Modification] 106695 for fuselage at S19 and mod 107824 for HTP to improve protection against corrosion, and issued [Airbus] SB [Service Bulletin] A350-53-P029 (Airbus mod 110281) and [Airbus] SB A350-55-P003 (Airbus mod 107877 and mod 108494) to provide modification instructions for in-service pre-mod aeroplanes.
For the reasons described above, this [EASA] AD requires application of sealant and protective treatment on the affected areas of the HTP and fuselage at S19 and, for certain aeroplanes, modification of the trimmable horizontal stabilizer (THS) torsion box [and re-identification of the elevator].

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-2018- 0506.

Comments

We gave the public the opportunity to participate in developing this final rule. We received no comments on the NPRM or on the determination of the cost to the public.

Conclusion

We reviewed the relevant data and determined that air safety and the public interest require adopting this final rule 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 addressing the unsafe condition; and
Do not add any additional burden upon the public than was already proposed in the NPRM.

Related Service Information Under 1 CFR Part 51

Airbus SAS has issued Service Bulletin A350-53-P029, dated November 17, 2017. This service information describes procedures to apply sealant and protective treatment on the affected areas of the rear fuselage cone structure.
Airbus SAS has issued Service Bulletin A350-55-P003, dated November 6, 2017. This service information describes procedures to apply sealant and protective treatment on the affected areas of the horizontal stabilizer, modify the THS torsion box in zone 330 and 340, and re- identify the elevator in zone 335 and 345.
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 6 airplanes of U.S. registry.
We estimate the following costs to comply with this AD:

Estimated Costs for Required Actions ----------------------------------------------------------------------------------------------------------------
Labor cost Parts cost Cost per product Cost on U.S. operators ---------------------------------------------------------------------------------------------------------------- Up to 57 work-hours x $85 per hour = Unavailable............ Up to $4,845........... Up to $29,070.
$4,845. ----------------------------------------------------------------------------------------------------------------

According to the manufacturer, some or all of the costs of this AD may be covered under warranty, thereby reducing the cost impact on affected individuals. We do not control warranty coverage for affected individuals. As a result, we have included all known costs in our cost estimate.

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 forpractices, 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 and associated appliances to the Director of the System Oversight Division.

Regulatory Findings

This AD will not have federalism implications under Executive Order 13132. This AD will not have a substantial direct effect on 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.