Document ID: FAA-2021-0839-0001
Agency: faa
Document Type: Proposed Rule
Title: Airworthiness Directives: Airbus Helicopters
Posted Date: 2021-09-30T04:00Z

[Federal Register Volume 86, Number 187 (Thursday, September 30, 2021)]
[Proposed Rules]
[Pages 54139-54142]
From the Federal Register Online via the Government Publishing Office [www.gpo.gov]
[FR Doc No: 2021-21199]

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DEPARTMENT OF TRANSPORTATION

Federal Aviation Administration

14 CFR Part 39

[Docket No. FAA-2021-0839; Project Identifier MCAI-2020-01697-R]
RIN 2120-AA64

Airworthiness Directives; Airbus Helicopters

AGENCY: Federal Aviation Administration (FAA), DOT.

ACTION: Notice of proposed rulemaking (NPRM).

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SUMMARY: The FAA proposes to supersede Airworthiness Directive (AD) 
2020-21-01, which applies to certain Airbus Helicopters Model AS-365N2, 
AS 365N3, EC 155B, EC155B1, and SA-365N1 helicopters. AD 2020-21-01 
requires modifying the main gearbox (MGB) tail rotor (T/R) drive flange 
installation. Since the FAA issued AD 2020-21-01, the FAA has 
determined that additional helicopters are affected by the unsafe 
condition. This proposed AD would continue to require modifying the MGB 
T/R drive flange installation, and would also include new helicopters 
in the applicability for the required actions. 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 
15, 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,

[[Page 54140]]

TX 75052; phone: (972) 641-0000 or (800) 232-0323; fax: (972) 641-3775; 
or at https://www.airbus.com/helicopters/services/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-2021-0839; 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; phone: (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-2021-0839; Project Identifier 
MCAI-2020-01697-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; phone: (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 2020-21-01, Amendment 39-21274 (85 FR 63440, 
October 8, 2020), (AD 2020-21-01), for certain Airbus Helicopters Model 
AS-365N2, AS 365N3, EC 155B, EC155B1, and SA-365N1 helicopters. AD 
2020-21-01 requires modifying the MGB T/R drive flange installation. AD 
2020-21-01 was prompted by several reported occurrences of loss of 
tightening torque of the Shur-Lok nut, which serves as a retainer of 
the T/R drive flange.
    EASA AD 2020-0287, dated December 21, 2020 (EASA AD 2020-0287), 
issued by EASA, which is the Technical Agent for the Member States of 
the European Union, to correct an unsafe condition for certain AS 365 
N2, AS 365 N3, SA 365 C1, SA 365 C2, SA 365 C3, SA 365 N and SA 365 N1 
helicopters; and all EC 155 B and EC 155 B1 helicopters. Model SA 365 
C3 airplanes are not certificated by the FAA and are not included on 
the U.S. type certificate data sheet; this proposed AD therefore does 
not include those airplanes in the applicability.
    EASA advised of reported occurrences of loss of tightening torque 
of the Shur-Lok nut, which serves as a retainer of the T/R drive flange 
of the MGB. EASA also advises of subsequent investigation that 
determined that these occurrences were the result of failure of the 
Shur-Lok nut locking function, which is normally ensured by two anti-
rotation tabs engaged into two slots at the end of the MGB output shaft 
pinion. EASA states this condition could lead to the loosening of the 
Shur-Lok nut and disengagement of the Shur-Lok nut threads, possibly 
resulting in reduction of T/R drive control, rear transmission 
vibrations, and subsequent reduced control of the helicopter.
    To address this unsafe condition, EASA issued a series of ADs, 
initially with EASA AD No. 2014-0165, dated July 14, 2014 (EASA AD 
2014-0165), which required a one-time inspection of the radial play 
inside the T/R drive flange and the condition of the Shur-Lok nut. 
Shortly after, EASA issued EASA AD No. 2014-0179, dated July 25, 2014 
(EASA AD 2014-0179) to supersede EASA AD 2014-0165. EASA AD 2014-0179 
retained the requirements of EASA AD 2014-0165 and expanded the 
applicability of helicopters affected by the unsafe condition. EASA 
later revised EASA AD 2014-0179 to Revision 1, dated July 29, 2014, to 
revise the applicability and specify updated related service 
information, and again to Revision 2, dated April 11, 2016 (EASA AD 
2014-0179R2), to reduce the applicability and specify additional 
updated related service information.
    Since EASA issued EASA AD 2014-0179R2, another occurrence was 
reported that involved an on-ground loss of T/R synchronization, 
resulting from disengagement of the Shur-Lok nut. This additional 
occurrence prompted EASA to issue EASA AD 2019-0046, dated March 11, 
2019 (EASA AD 2019-0046) (which prompted FAA AD 2020-20-01), to require 
installation of modification 07 63C81, which consists of installing a 
rear output stop with 5 spigots on the T/R shaft flexible coupling. 
According to Airbus Helicopters, the 5 spigots will come into contact 
with the row of 5 bolt heads of the front T/R shaft if the T/R drive 
flange moves backwards. This contact limits backward displacement of 
the T/R drive flange and subsequently prevents T/R drive flange 
disengagement.
    Since EASA issued EASA AD 2019-0046, Airbus Helicopters reviewed 
the applicability of modification 07 63C81 and developed an additional 
4 spigot modification (07 63D01) that was applicable to an additional 
subset of in-service helicopter models that were initially excluded 
from the applicability of EASA AD 2014-0179R2, prompting EASA to issue 
EASA AD 2020-0212, dated October 5, 2020 (EASA AD 2020-0212), to 
require either a 4 spigot or 5 spigot modification for the originally 
excluded helicopter models (which was dependent on the front shaft 
configuration, on the T/R shaft flexible coupling).

[[Page 54141]]

Actions Since AD 2020-21-01 Was Issued

    Since the FAA issued AD 2020-21-01, EASA issued EASA AD 2020-0287, 
which supersedes EASA AD 2020-0212. EASA advises that modification of 
the MGB T/R drive flange is necessary for additional helicopters that 
were originally excluded from the previous EASA ADs due to date of 
manufacture. This condition, if not addressed, could result in 
loosening of the Shur-Lok nut, possibly resulting in disengagement of 
the Shur-Loc nut threads, reduction of T/R drive control, rear 
transmission vibrations, and subsequent reduced control of the 
helicopter.
    Accordingly, EASA AD 2020-0287 retains the modification of the MGB 
T/R drive flange installation. EASA AD 2020-0287 also includes new 
helicopters in the applicability for the required actions (Model SA-
365C1, SA-365C2, and SA-365N helicopters on which Airbus Helicopters 
modification 0763B64 has been embodied; and Model EC 155B and EC155B1 
helicopters without modification 0763B64 embodied).

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 these same type designs.

Related Service Information Under 1 CFR Part 51

    The FAA reviewed the following service information.
    Airbus Helicopters Alert Service Bulletin (ASB) No. AS365-63.00.26, 
Revision 0, dated July 22, 2020, for Model AS365N helicopters and non 
FAA-type certificated military Model AS365Fs helicopters; and Airbus 
Helicopters ASB No. SA365-65.52, Revision 1 and dated July 22, 2020, 
for Model SA-365C1 and SA-365C2 helicopters and non FAA-type 
certificated Model SA-365C3 helicopters. This service information 
specifies procedures for modifying the MGB T/R drive flange 
installation, which include installing a rear (aft) output stop between 
the T/R drive flange and T/R drive shaft. These documents are distinct 
since they apply to different helicopter models.
    This proposed AD also requires Airbus Helicopters ASB No. AS365-
63.00.19, Revision 1, dated January 31, 2019; and Airbus Helicopters 
ASB No. EC155-63A013, Revision 1, dated January 31, 2019; which the 
Director of the Federal Register approved for incorporation by 
reference as of November 12, 2020 (85 FR 63440, October 8, 2020).
    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 all of the requirements of AD 2020-
21-01. This proposed AD would require modifying the MGB T/R drive 
flange installation, and would also include new helicopters in the 
applicability for the required actions. This proposed AD would also 
require accomplishing the actions specified in the service information 
already described.

Differences Between This Proposed AD and the EASA AD

    EASA AD 2020-0287 specifies compliance times of 600 flight hours or 
a certain time frame (months). However, this proposed AD would only 
require the compliance time of 600 hours time-in-service.

Costs of Compliance

    The FAA estimates that this AD, if adopted as proposed, would 
affect 53 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.

                                                                     Estimated Costs
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              Action                      Labor cost                 Parts cost                  Cost per product             Cost on U.S. operators
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Modification (46 helicopters)       14 work-hours x $85    $2,704.......................  $3,894.......................  $179,124.
 (retained actions from AD 2020-21-  per hour = $1,190.
 01).
Modification (new proposed action)  14 work-hours x $85    Up to $18,474................  Up to $19,664................  Up to $1,042,192.
                                     per hour = $1,190.
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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.

[[Page 54142]]

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

0
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]

0
2. The FAA amends Sec.  39.13 by:
0
a. Removing Airworthiness Directive 2020-21-01, Amendment 39-21274 (85 
FR 63440, October 8, 2020); and
0
b. Adding the following new airworthiness directive:

Airbus Helicopters: Docket No. FAA-2021-0839; Project Identifier 
MCAI-2020-01697-R.

(a) Comments Due Date

    The FAA must receive comments on this airworthiness directive 
(AD) action by November 15, 2021.

(b) Affected ADs

    This AD replaces AD 2020-21-01, Amendment 39-21274 (85 FR 63440, 
October 8, 2020) (AD 2020-21-01).

(c) Applicability

    This AD applies to the Airbus Helicopters model helicopters, 
certificated in any category, as identified in paragraphs (c)(1) 
through (3) of this AD.
    (1) Model AS-365N2, AS 365 N3, and SA-365N1, all serial numbers 
on which Airbus Helicopters modification 0763B64 has been embodied, 
except those on which Airbus Helicopters modification 0763C81 has 
been embodied.
    (2) Model SA-365C1, SA-365C2, and SA-365N, all serial numbers on 
which Airbus Helicopters modification 0763B64 has been embodied.
    (3) Model EC 155B and EC155B1, all serial numbers, except those 
on which Airbus Helicopters modification 0763C81 has been embodied.

(d) Subject

    Joint Aircraft Service Component (JASC) Code: 6500, Tail Rotor 
Drive System.

(e) Unsafe Condition

    This AD was prompted by several reported occurrences of loss of 
tightening torque of the Shur-Lok nut, which serves as a retainer of 
the main gear box (MGB) tail rotor (T/R) drive flange. The FAA is 
issuing this AD to detect and address loss of tightening torque of 
the Shur-Lok nut. The unsafe condition, if not addressed, could 
result in loosening of the Shur-Lok nut, possibly resulting in 
disengagement of the Shur-Lok nut threads, reduction of T/R drive 
control, rear transmission vibrations, and subsequent reduced 
control of the helicopter.

(f) Compliance

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

(g) Retained Actions of Paragraph (e) of AD 2020-21-01 With No Changes

    This paragraph restates the requirements of paragraph (e) of AD 
2020-21-01 with no changes. Within 600 hours time-in-service after 
November 12, 2020 (the effective date of AD 2020-21-01:
    (1) For Model AS-365N2, AS 365N3, and SA-365N1 helicopters:
    (i) Without removing the tail drive shaft flange (a), remove the 
sliding flange (b) from the flexible coupling (c) as shown in Detail 
``B'' of Figure 1, PRE MOD, of Airbus Helicopters Alert Service 
Bulletin (ASB) No. AS365-63.00.19, Revision 1, dated January 31, 
2019 (ASB AS365-63.00.19, Revision 1); replace the 3 bolts (d) and 
remove from service the 3 washers (e).
    (ii) Install the sliding flange (b) with aft output stop (1) 
part number (P/N) 365A32-7836-20 as shown in Detail ``B'' of Figure 
1, POST MOD, of ASB AS365-63.00.19, Revision 1, and by following the 
Accomplishment Instructions, paragraph 3.B.2.b, of ASB AS365-
63.00.19, Revision 1.
    (2) For Model EC 155B and EC155B1 helicopters with modification 
0763B64 embodied:
    (i) Without removing the Shur-Lok nut (a), remove the sliding 
flange (b) from the flexible coupling (c) as shown in Detail ``B'' 
of Figure 1, PRE MOD, of Airbus Helicopters ASB No. EC155-63A013, 
Revision 1, dated January 31, 2019 (ASB EC155-63A013, Revision 1); 
replace the 3 bolts (d) and remove from service the 3 washers (e).
    (ii) Install the sliding flange (b) with aft output stop (1) P/N 
365A32-7836-20 as shown in Detail ``B'' of Figure 1, POST MOD, of 
ASB EC155-63A013, Revision 1, and by following the Accomplishment 
Instructions, paragraph 3.B.2.b, of ASB EC155-63A013, Revision 1.
    Note 1 to paragraph (g)(2)(ii): ASB EC155-63A013, Revision 1 
refers to the ``aft output stop'' as ``rear output stop.''

(h) New Required Actions

    For Model SA-365C1, SA-365C2, and SA-365N helicopters; and Model 
EC 155B and EC155B1 helicopters without modification 0763B64 
embodied: Within 600 hours time-in-service after the effective date 
of this AD, modify the MGB T/R drive flange installation, in 
accordance with paragraph 3.B.2., ``Procedure,'' of the 
Accomplishment Instructions of the applicable service information 
specified in paragraphs (h)(1) through (3) of this AD, except as 
specified in paragraph (i) of this AD.
    (1) Airbus Helicopters ASB SA365-65.52, Revision 1, dated July 
22, 2020.
    (2) Airbus Helicopters ASB AS365-63.00.26, Revision 0, dated 
July 22, 2020.
    (3) ASB EC155-63A013, Revision 1.

(i) Exceptions to Service Information

    Where the service information identified in paragraph (h) of 
this AD specifies to discard certain parts, this AD requires 
removing those parts from service.

(j) Special Flight Permits

    Special flight permits, as described in 14 CFR 21.197 and 
21.199, are not allowed.

(k) 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 (l)(1) of 
this AD. Information may be emailed to: 9-AVS-AIR-730-AMOC@faa.gov.
    (2) 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.

(l) 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; phone: (516) 228-7330; 
email: andrea.jimenez@faa.gov.
    (2) For service information identified in this AD, contact 
Airbus Helicopters, 2701 North Forum Drive, Grand Prairie, TX 75052; 
phone: (972) 641-0000 or (800) 232-0323; fax: (972) 641-3775; or at 
https://www.airbus.com/helicopters/services/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 2020-0287, dated December 21, 2020. 
You may view the EASA AD on the internet at https://www.regulations.gov in Docket No. FAA-2021-0839.

    Issued on September 24, 2021.
Gaetano A. Sciortino,
Deputy Director for Strategic Initiatives, Compliance & Airworthiness 
Division, Aircraft Certification Service.
[FR Doc. 2021-21199 Filed 9-29-21; 8:45 am]
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