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Federal Register / Vol. 86, No. 193 / Friday, October 8, 2021 / Proposed Rules 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 which is not specifically designated as CBI will be placed in the public docket for this rulemaking.

jspears on DSK121TN23PROD with PROPOSALS1

Background The FAA issued AD 20201105, Amendment 3921130 85 FR 31042, May 22, 2020 AD 20201105, for Airbus Helicopters Model EC120B
helicopters, all serial numbers. AD
20201105 requires repetitive inspections of the TR hub body for cracks and applicable corrective actions if necessary, and repetitive replacement of the attachment bolts, washers, and nuts of the TR hub body. AD 202011
05 was prompted by EASA AD 2019
0272R1, dated November 18, 2019
EASA AD 20190272R1, issued by EASA, which is the Technical Agent for the Member States of the European Union, to correct an unsafe condition for Airbus Helicopters, formerly Eurocopter, Eurocopter France, Model EC120 B helicopters. EASA advised that an inspection of the TR hub body revealed a recurring loss of tightening torque on several attachment bolts. This condition, if not addressed, could result in cracking and potential loss of the TR
drive and consequent loss of yaw control of the helicopter.
Accordingly, EASA AD 20190272R1
required repetitive inspections of the TR
hub body for cracks and applicable corrective actions if necessary, as well as repetitive replacement of the associated attachment bolts, washers, and nuts.
Actions Since AD 20201105 Was Issued Since the FAA issued AD 202011
05, EASA issued AD 20210069, dated March 11, 2021 EASA AD 20210069, which supersedes EASA AD 2019
0272R1. EASA advises that further detailed analysis showed that a loss of tightening torque in the interface between the TR hub body and splined flange creates the risk of crack initiation from a fretting area located on the TR
hub body and splined flange or on the TR hub body and flange bolts.

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Accordingly, EASA AD 20210069
retains the requirements of EASA AD
20190272R1 and requires additional repetitive detailed inspections of the interface between the TR hub body part number P/N C642A0100103 and the splined flange. Depending on the inspection results, EASA AD 20210069
requires accomplishment of applicable corrective actions.
FAAs Determination 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 the same type designs.
Related Service Information Under 1
CFR Part 51
The FAA reviewed Airbus Helicopters Emergency Alert Service Bulletin 05A020, Revision 2, dated February 8, 2021 ASB 05A020 Rev 2. This service information specifies procedures for repetitive inspections of the TR hub body for cracks and the TR spline flange for cracks and fretting and the appropriate corrective actions.
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.
Proposed AD Requirements in This NPRM
This proposed AD would retain some of the requirements of AD 20201105, and would require, within 15 hours time-in-service TIS or 7 days, whichever occurs first, performing repetitive inspections of the TR hub body for a crack and depending on the inspection results, removing the affected parts from service. This proposed AD
would also require inspecting the TR
spline flange for corrosion, impacts, fretting, wear, and a crack and depending on the inspection results, removing the TR splined flange from service. For helicopters with 9,000 or more total hours TIS or with unknown total hours TIS, this proposed AD would require, within 15 hours TIS or 7 days, whichever occurs first, and thereafter at intervals not to exceed 1,000 hours TIS, removing from service any bolt, washer, and nut installed on the TR hub body, replacing them with airworthy parts, inspecting the TR splined flange, and
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depending on the inspection results, removing the TR splined flange from service. This proposed AD would also require, for helicopters with less than 9,000 total hours TIS, within 1,000
hours TIS or before accumulating 9,000
total hours TIS, whichever occurs first, and thereafter at intervals not to exceed 1,000 hours TIS, removing from service any bolt, washer, and nut installed on the TR hub body replacing them with airworthy parts, inspecting the TR
splined flange, and depending on the inspection results, removing the TR
splined flange from service. This proposed AD would also prohibit the installation of a certain part-numbered TR hub body unless certain actions have been accomplished.
Differences Between This Proposed AD
and EASA AD 20210069
EASA AD 20210069 uses flight hours FH for certain compliance times, whereas this proposed AD uses hours TIS. EASA AD 20210069 retains the compliance time of November 1, 2019
for certain actions, which is the effective date of EASA AD 20190272R1, whereas this proposed AD would require compliance as of the effective date of the proposed AD.
Where Note 1 of EASA AD 20210069
allows a non-cumulative tolerance of 100 hours TIS to be applied to the compliance times for the initial replacement of bolts, washers, and nuts Table 1 of EASA AD 20210069 to allow for synchronization of the required inspections with other maintenance tasks, this proposed AD
would not allow a non-cumulative tolerance of 100 hours TIS to be applied to the compliance times.
Costs of Compliance The FAA estimates that this AD, if adopted as proposed, would affect 89
helicopters of U.S. Registry. Labor rates are estimated at $85 per work-hour.
Based on these numbers, the FAA
estimates the following costs to comply with this proposed AD.
Visually inspecting each TR hub body for a crack would take about 0.25 workhour for an estimated cost of $22 per inspection and $1,958 for the U.S. fleet.
Visually inspecting each TR spline flange for corrosion, impacts, fretting, wear, and a crack would take about 0.25
work-hour for an estimated cost of $22
per inspection and $1,958 for the U.S.
fleet.
Replacing a TR hub body would take about 2 work-hours and parts would cost about $16,417 for an estimated cost of $16,587 per TR hub body replacement.

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