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PROPOSED AD AIRBUS HELICOPTERS: Docket No. FAA-2021-0872; Project Identifier MCAI-2021-00312-R
(a) COMMENTS DUE DATE

    The FAA  must receive  comments on  this airworthiness  directive (AD)
    action by November 22, 2021.

(b) AFFECTED ADS

    This AD replaces AD 2020-11-05,  Amendment 39-21130  (85 FR 31042, May
    22, 2020) (AD 2020-11-05).

(c) APPLICABILITY

    This AD applies to Airbus Helicopters Model EC120B helicopters, certif
    -icated in any category, all serial numbers.

(d) SUBJECT

    Joint Aircraft Service Component (JASC) Code: 6400, Tail rotor system.

(e) UNSAFE CONDITION

    This  AD was  prompted by  a report  of recurrent  loss of  tightening
    torque on several  attachment bolts on  the tail rotor  (TR) hub body.
    The FAA is issuing this AD  to detect cracking and fretting, which  if
    not addressed,  could result  in potential  loss of  the TR  drive and
    consequent loss of yaw control of the helicopter.

(f) COMPLIANCE

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

(g) REQUIRED ACTIONS

(1) Within 15 hours time-in-service  (TIS)  or  7 days,  whichever  occurs
    first after the effective date of this AD, and thereafter at intervals
    not to exceed 15 hours TIS, using a light source and mirror,  visually
    inspect TR hub body part number (P/N) C642A0100103 for a crack in  the
    entire  inspection area  depicted in  Figure 1  of Airbus  Helicopters
    Emergency Alert Service Bulletin 05A020 Revision 2,  dated February 8,
    2021 (ASB 05A020 Rev 2). If  there is a crack, before further  flight,
    perform the actions in paragraphs (g)(1)(i) and (ii) of this AD.

(i) Remove the TR hub body and each bolt, washer, and nut installed on the
    TR hub body from service and replace with airworthy parts.

(ii) Inspect the TR splined flange for corrosion, impacts, fretting, wear,
     and a crack in  the areas identified in  Figure 2 of this  AD. If the
     condition of the part (including corrosion, impacts, fretting,  wear,
     or cracks) exceeds the criteria as specified in Figure 1 of this  AD,
     before further  flight, remove  the splined  flange from  service and
     replace with an airworthy part.

Note 1 to paragraph (g)(1)(ii): You may refer to "Detailed Check - Splined
Flange," Task  64-21-00,  6-5,  Airbus Aircraft Maintenance Manual  (AMM),
dated October 15, 2020 which pertains to the TR splined flange inspection.

    FIGURE 1 TO PARAGRAPH (G)(1)(II)   INSPECTION CRITERIA FOR TAIL ROTOR
                                        SPLINED FLANGE                    
    ______________________________________________________________________
    LOCATION AS SPECIFIED IN         MAXIMUM DAMAGE, WHICH CAUSES REPLACE-
    FIGURE 2 TO PARAGRAPH            MENT (E1,DIA. 2, DIA. 3, AND DIA. 4
    (G)(1)(II) OF THIS AD            ARE SHOWN IN FIGURE 2 TO PARAGRAPH
                                     (G)(1)(II) OF THIS AD)
    ______________________________________________________________________
    Zone A                           Scratch depth > 0.2 mm (0.008 in.).
                                     Crack.
                                     E1 < 2.75 mm (0.108 in.).
                                     Dia. 3 > 6.02 mm (0.2371 in.).
                                     Dia. 2 > 33.03 mm (1.3004 in.).

    Zone B                           Touch-up depth > 0.1 mm (0.004 in.).
                                     Crack.

    Zone C                           Crack.
                                     Scratch depth > 0.2 mm (0.008 in.).

    Zone D [Dia. 4 = 14 mm           Touch-up depth > 0.1 mm (0.004 in.).
    +/- 0.1 mm (0.548;               Crack.
    0.555in.)]                       E1 < 2.75 mm (0.108 in.).
    ______________________________________________________________________


                           ILLUSTRATION (Figure 2)


(2) For helicopters with 9,000 or more total hours TIS,  or  with  unknown
    total hours TIS, within 15 hours TIS or 7 days, whichever occurs first
    after the effective date of  this AD, and thereafter at  intervals not
    to exceed 1,000 hours TIS, remove each bolt, washer, and nut installed
    on the TR hub body from  service and replace with airworthy parts  and
    perform the actions in paragraph (g)(1)(ii) of this AD.

(3) 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 after  the effective date  of this AD,  and thereafter at
    intervals not to exceed 1,000 hours TIS, remove each bolt, washer, and
    nut  installed  on the  TR  hub body  from  service and  replace  with
    airworthy parts  and perform  the actions  in paragraph  (g)(1)(ii) of
    this AD.

(4) As of the effective date  of this AD,  do not install  TR hub body P/N
    C642A0100103 on any helicopter, unless the actions of paragraph (g)(1)
    of this AD have been accomplished.

(h) SPECIAL FLIGHT PERMITS

    A special flight  permit may be  permitted provided that  there are no
    passengers onboard.

(i) ALTERNATIVE METHODS OF COMPLIANCE (AMOCS)

(1) The Manager, International Validation 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 manager  of the
    International  Validation  Branch, send  it  to the  attention  of the
    person identified in paragraph (j)(1)  of this AD. Information may  be
    emailed to: 9-AVS-AIR730-AMOC@faa.gov.

(2) Before using any approved AMOC,  notify your appropriate principal in-
    spector, or lacking  a principal inspector,  the manager of  the local
    flight standards district office/certificate holding district office.

(j) RELATED INFORMATION

(1) For more information about this AD,  contact 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) 228-7330; email andrea.jimenez@faa
    .gov.

(2) For service information identified in this AD, contact Airbus Helicop-
    ters, 2701 North Forum Drive, Grand Prairie, TX 75052; telephone (972)
    641-0000 or (800)232-0323; fax (972) 641-3775 or at https://www.airbus
    .com/helicopters/services/technical-support.html.  You  may  view this
    referenced  service information  at  the  FAA,  Office of the Regional
    Counsel,  Southwest Region,  10101 Hillwood Pkwy.,  Room 6N-321,  Fort
    Worth, TX 76177.  For information on the availability of this material
    at the FAA, call (817) 222-5110.

(3) The subject of this AD is addressed  in European Union Aviation Safety
    Agency (EASA) AD 2021-0069, dated March 11, 2021.  You  may  view  the
    EASA AD on the Internet  at https://www.regulations.gov  in Docket No.
    FAA-2021-0872.

Issued on October 1, 2021. Lance T. Gant, Director, Compliance & Airworth-
iness Division, Aircraft Certification Service.

DATES: The FAA must receive comments  on this proposed AD  by November 22,
2021.
PREAMBLE 

DEPARTMENT OF TRANSPORTATION

Federal Aviation Administration

14 CFR Part 39

[Docket No. FAA-2021-0872; Project Identifier MCAI-2021-00312-R]
RIN 2120-AA64

Airworthiness Directives; Airbus Helicopters

AGENCY: Federal Aviation Administration (FAA), DOT.

ACTION: Notice of proposed rulemaking (NPRM).

-----------------------------------------------------------------------

SUMMARY: The FAA proposes to supersede Airworthiness Directive (AD)
2020-11-05, which applies to all Airbus Helicopters Model EC120B
helicopters. AD 2020-11-05 requires repetitive inspections of the tail
rotor (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. This proposed AD would retain certain
requirements of AD 2020-11-05, add repetitive inspections, require
additional corrective actions, and update applicable service
information. The FAA is proposing this AD to address the unsafe
condition on these products.

DATES: The FAA must receive comments on this proposed AD by November
22, 2021.

ADDRESSES: You may send comments, using the procedures found in 14 CFR
11.43 and 11.45, by any of the following methods:
Federal eRulemaking Portal: Go to https://www.regulations.gov. Follow the instructions
for submitting comments.
Fax: (202) 493-2251.
Mail: U.S. Department of Transportation, Docket
Operations, M-30, West Building Ground Floor, Room W12-140, 1200 New
Jersey Avenue SE, Washington, DC 20590.
Hand Delivery: Deliver to Mail address above between 9
a.m. and 5 p.m., Monday through Friday, except Federal holidays.
For service information identified in this NPRM, contact Airbus
Helicopters, 2701 North Forum Drive, Grand Prairie, TX 75052; telephone
(972) 641-0000 or (800) 232-0323; fax (972) 641-3775; or at https://www.airbus.com/helicopters/services/technical-support.html. You may
view this service information at the FAA, Office of the Regional
Counsel, Southwest Region, 10101 Hillwood Pkwy., Room 6N-321, Fort
Worth, TX 76177. For information on the availability of this material
at the FAA, call (817) 222-5110.

Examining the AD Docket

You may examine the AD docket at https://www.regulations.gov by
searching for and locating Docket No. FAA-2021-0872; or in person at
Docket Operations between 9 a.m. and 5 p.m., Monday through Friday,
except Federal holidays. The AD docket contains this NPRM, the European
Union Aviation Safety Agency (EASA) AD, any comments received, and
other information. The street address for Docket Operations is listed
above.

FOR FURTHER INFORMATION CONTACT: 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) 228-7330; email andrea.jimenez@faa.gov.

SUPPLEMENTARY INFORMATION:

Comments Invited

The FAA invites you to send any written relevant data, views, or
arguments about this proposal. Send your comments to an address listed
under ADDRESSES. Include ``Docket No. FAA-2021-0872; Project Identifier
MCAI-2021-00312-R'' at the beginning of your comments. The most helpful
comments reference a specific portion of the proposal, explain the
reason for any recommended change, and include supporting data. The FAA
will consider all comments received by the closing date and may amend
this proposal because of those comments.
Except for Confidential Business Information (CBI) as described in
the following paragraph, and other information as described in 14 CFR
11.35, the FAA will post all comments received, without change, to
https://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) 228-7330; 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.

Background

The FAA issued AD 2020-11-05, Amendment 39-21130 (85 FR 31042, May
22, 2020) (AD 2020-11-05), for Airbus Helicopters Model EC120B
helicopters, all serial numbers. AD 2020-11-05 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 2020-11-05 was prompted
by EASA AD 2019-0272R1, dated November 18, 2019 (EASA AD 2019-0272R1),
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 2019-0272R1 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 2020-11-05 Was Issued

Since the FAA issued AD 2020-11-05, EASA issued AD 2021-0069, dated
March 11, 2021 (EASA AD 2021-0069), 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. Accordingly, EASA AD 2021-0069 retains the
requirements of EASA AD 2019-0272R1 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 2021-0069 requires accomplishment of
applicable corrective actions.

FAA's Determination

These helicopters have been approved by EASA and are approved for
operation in the United States. Pursuant to the FAA's 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 2020-
11-05, 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 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 2021-0069

EASA AD 2021-0069 uses flight hours (FH) for certain compliance
times, whereas this proposed AD uses hours TIS. EASA AD 2021-0069
retains the compliance time of November 1, 2019 for certain actions,
which is the effective date of EASA AD 2019-0272R1, whereas this
proposed AD would require compliance as of the effective date of the
proposed AD.
Where Note 1 of EASA AD 2021-0069 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 2021-0069)
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 work-hour 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.

Replacing a TR spline flange would take about 0.5 work-hour and
parts would cost about $2,950 for an estimated cost of $2,993 per TR
spline flange replacement.
Replacing a bolt, washer, and nut would take about 0.5 work-hour
and parts would cost about $68 for an estimated cost of $111 per
replacement.

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.
The FAA is 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.

Regulatory Findings

The FAA determined that this proposed AD would not have federalism
implications under Executive Order 13132. This proposed AD would 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, I certify this proposed regulation:
(1) Is not a ``significant regulatory action'' under Executive
Order 12866,
(2) Would not affect intrastate aviation in Alaska, and
(3) Would 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.

The Proposed Amendment

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

PART 39--AIRWORTHINESS DIRECTIVES

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

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

Sec. 39.13 [Amended]

2. The FAA amends Sec. 39.13 by:

a. Removing Airworthiness Directive 2020-11-05, Amendment 39-21130 (85
FR 31042, May 22, 2020); and

b. Adding the following new airworthiness directive: