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Federal Register / Vol. 86, No. 119 / Thursday, June 24, 2021 / Proposed Rules
www.regulations.gov, including any personal information you provide. The agency will also post a report summarizing each substantive verbal contact received about this NPRM.
Confidential Business Information CBI is commercial or financial information that is both customarily and actually treated as private by its owner.
Under the Freedom of Information Act FOIA 5 U.S.C. 552, CBI is exempt from public disclosure. If your comments responsive to this NPRM
contain commercial or financial information that is customarily treated as private, that you actually treat as private, and that is relevant or responsive to this NPRM, it is important that you clearly designate the submitted comments as CBI. Please mark each page of your submission containing CBI
as PROPIN. The FAA will treat such marked submissions as confidential under the FOIA, and they will not be placed in the public docket of this NPRM. Submissions containing CBI
should be sent to Andrea Jimenez, Aerospace Engineer, COS Program Management Section, Operational Safety Branch, Compliance &
Airworthiness Division, FAA, 1600
Stewart Ave., Suite 410, Westbury, NY
11590; telephone 516 2287330; email andrea.jimenez@faa.gov. Any commentary that the FAA receives that is not specifically designated as CBI will be placed in the public docket for this rulemaking.

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Background EASA, which is the Technical Agent for the Member States of the European Union, has issued EASA AD 20180292, dated December 28, 2018 EASA AD
20180292 to correct an unsafe condition for Leonardo S.p.A. formerly Finmeccanica S.p.A, AgustaWestland S.p.A., Agusta S.p.A.; AgustaWestland Philadelphia Corporation, formerly Agusta Aerospace Corporation Model AB139 and Model AW139 helicopters, all serial numbers. Although EASA AD
20180292 applies to all Model AB139
and Model AW139 helicopters, this proposed AD would apply to helicopters with an affected part installed instead.
This proposed AD was prompted by a report that, during a post-flight inspection of an in-service helicopter, a tail rotor slider assembly was found fractured, and the bushing and the actuator rod in the tail rotor servo were
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partially damaged. The subsequent investigation revealed that the failure was due to fatigue, initiated from corroded areas corrosion craters on the surface of the tail rotor slider assembly characterized by signs of circumferential refinishing. The corrosion craters originated along finishing signs consistent with low grit sanding operations, which can remove the passivation corrosion protection from the tail rotor slider assembly. Sanding is a maintenance activity that is not included in the maintenance manual for Leonardo S.p.a. Model AB139 and AW139 helicopters and is not allowed on in-service helicopters. The FAA is proposing this AD to address corrosion in the tail rotor slider assembly caused by improper refinishing characterized by signs of circumferential refinishing consistent with sanding. The unsafe condition, if not addressed, could result in fatigue cracks and fracture of the tail rotor slider assembly, resulting in failure of the tail rotor controls and consequent loss of yaw control of the helicopter. See EASA AD 20180292 for additional background information.
FAAs Determination and Requirements of This Proposed AD
These helicopters have been approved by EASA and are approved for operation in the United States. Pursuant to the FAAs bilateral agreement with the European Union, EASA has notified the FAA about the unsafe condition described in its AD. The FAA is proposing this AD after evaluating all known relevant information and determining that the unsafe condition described previously is likely to exist or develop on other helicopters of these same type designs.
Related Service Information Under 1
CFR Part 51
EASA AD 20180292 requires a detailed inspection of the tail rotor slide assembly for corrosion and signs of circumferential refinishing and, depending on the findings, applicable corrective actions. If there is any evidence of corrosion craters the corrective action is replacement of the affected part with a serviceable part. If there is any evidence of surface imperfections caused by circumferential refinishing but no evidence of corrosion, the corrective action is repetitive inspections of the tail rotor slide assembly for corrosion and signs of circumferential refinishing.

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Replacement of an affected part with a serviceable part is terminating action for the repetitive inspections.
This material 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.
Proposed AD Requirements in This NPRM
This proposed AD would require accomplishing the actions specified in EASA AD 20180292, described previously, as incorporated by reference, except for any differences identified as exceptions in the regulatory text of this proposed AD.
Explanation of Required Compliance Information In the FAAs ongoing efforts to improve the efficiency of the AD
process, the FAA developed a process to use certain civil aviation authority CAA ADs as the primary source of information for compliance with requirements for corresponding FAA
ADs. The FAA has been coordinating this process with manufacturers and CAAs. As a result, EASA AD 20180292
will be incorporated by reference in the FAA final rule. This proposed AD
would, therefore, require compliance with EASA AD 20180292 in its entirety, through that incorporation, except for any differences identified as exceptions in the regulatory text of this proposed AD. Using common terms that are the same as the heading of a particular section in EASA AD 2018
0292 does not mean that operators need comply only with that section. For example, where the AD requirement refers to all required actions and compliance times, compliance with this AD requirement is not limited to the section titled Required Actions and Compliance Times in EASA AD
20180292. Service information specified in EASA AD 20180292 that is required for compliance with it will be available at https www.regulations.gov by searching for and locating Docket No.
FAA20210507 after the FAA final rule is published.
Costs of Compliance The FAA estimates that this AD, if adopted as proposed, would affect 129
helicopters of U.S. Registry. The FAA
estimates the following costs to comply with this proposed AD.

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