[Federal Register Volume 86, Number 175 (Tuesday, September 14, 2021)]
[Proposed Rules]
[Pages 51038-51041]
From the Federal Register Online via the Government Publishing Office [www.gpo.gov]
[FR Doc No: 2021-19605]


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DEPARTMENT OF TRANSPORTATION

Federal Aviation Administration

14 CFR Part 39

[Docket No. FAA-2021-0728; Project Identifier MCAI-2020-00656-R]
RIN 2120-AA64


Airworthiness Directives; Bell Textron Canada Limited

AGENCY: Federal Aviation Administration (FAA), DOT.

ACTION: Notice of proposed rulemaking (NPRM).

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SUMMARY: The FAA proposes to adopt a new airworthiness directive (AD) 
for certain Bell Textron Canada Limited Model 206, 206A, 206A-1, 206B, 
206B-1, 206L, 206L-1, 206L-3, and 206L-4 helicopters. This proposed AD 
was

[[Page 51039]]

prompted by reports of cracked or missing nuts on the tail rotor drive 
shaft (TRDS) disc pack (Thomas) couplings. This proposed AD would 
require removing certain nuts from service, installing newly designed 
nuts, and applying a specific torque and a torque stripe to each newly 
installed nut. This proposed AD would then require, after the 
installation of each newly designed nut, inspecting the torque and, 
depending on the inspection results, either applying a torque stripe or 
performing further inspections and removing certain parts from service. 
Finally, this proposed AD would prohibit installing any affected nut on 
any TRDS Thomas coupling.
    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 October 29, 
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 between 9 a.m. and 
5 p.m., Monday through Friday, except Federal holidays.
    For service information identified in this NPRM, contact Bell 
Textron Canada Limited, 12,800 Rue de l'Avenir, Mirabel, Quebec J7J 
1R4, Canada; telephone 1-450-437-2862 or 1-800-363-8023; fax 1-450-433-
0272; email productsupport@bellflight.com; or at https://www.bellflight.com/support/contact-support. 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-2021-0728; 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 
Transport Canada AD, any comments received, and other information. The 
street address for Docket Operations is listed above.

FOR FURTHER INFORMATION CONTACT: Matt Fuller, AD Program Manager, 
General Aviation & Rotorcraft Unit, Airworthiness Products Section, 
Operational Safety Branch, FAA, 10101 Hillwood Pkwy., Fort Worth, TX 
76177; telephone (817) 222-5110; email matthew.fuller@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-2021-0728; Project Identifier 
MCAI-2020-00656-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 Matt 
Fuller, AD Program Manager, General Aviation & Rotorcraft Unit, 
Airworthiness Products Section, Operational Safety Branch, FAA, 10101 
Hillwood Pkwy., Fort Worth, TX 76177; telephone (817) 222-5110; email 
matthew.fuller@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

    Transport Canada, which is the aviation authority for Canada, has 
issued Canadian AD CF-2019-34, dated September 25, 2019 (Transport 
Canada AD CF-2019-34), to correct an unsafe condition for Bell 
Helicopter Textron Canada Limited (now Bell Textron Canada Limited) 
Model 206, 206A, 206A-1, 206B, 206B-1, 206L, 206L-1, 206L-3, and 206L-4 
helicopters, all serial numbers. Transport Canada AD CF-2019-34 advised 
of reports of cracked or missing nuts at the TRDS Thomas couplings, 
which could have been caused by improper torque or hydrogen 
embrittlement. This condition, if not addressed, could result in loss 
of the tail rotor and subsequent loss of control of the helicopter.
    After Transport Canada issued Transport Canada AD CF-2019-34, it 
was determined that helicopters modified in accordance with 
Supplemental Type Certificate (STC) SH2750NM or Transport Canada STC 
SH99-202, were not able to comply with AD CF-2019-34. Accordingly, 
Transport Canada issued AD CF-2020-15, dated May 13, 2020 (Transport 
Canada AD CF-2020-15) which supersedes Transport Canada AD CF-2019-34, 
and contains a new requirement for helicopters with STC SH2750NM or 
Transport Canada STC SH99-202 installed or models that have been 
modified per Bell Service Instruction BHT-206-SI-2052, Revision 1, 
dated October 14, 2010 (BHT-206-SI-2052). Transport Canada advises for 
certain model helicopters, the newly designed nuts cannot be installed 
because STC SH2750NM and Transport Canada STC SH99-202 install a pulley 
at the Thomas coupling location causing insufficient clearance. 
Transport Canada further advises for certain model helicopters with STC 
SH2750NM or Transport Canada STC SH99-202 installed, different part-
numbered nuts may be installed which were not identified in the 
applicable service information and are now required to be replaced with 
a new part-numbered nut that is not vulnerable to the unsafe condition. 
Accordingly, Air Comm Corporation, the STC holder for STC SH2750NM, 
issued new service information to address these additional issues and 
provide newly developed instructions which apply to certain model 
helicopters with STC SH2750NM or Transport Canada STC SH99-202 
installed.

[[Page 51040]]

    Additionally, Transport Canada advises that BHT-206-SI-2052 which 
is optional, specifies procedures for Model 206L-1 and 206L-3 
helicopters to upgrade the airframe and systems and also includes 
installation of the Model 206L-4 TRDS Thomas coupling. According to 
Transport Canada, models that have incorporated BHT-206-SI-2052, with 
STC SH2750NM or Transport Canada STC SH99-202 installed, will have the 
Model 206L-4 helicopter pulley configuration and are subject to the Air 
Comm Corporation service information.
    Accordingly, Transport Canada AD CF-2020-15 requires the 
replacement of the affected nuts with the newly designed nuts at each 
TRDS Thomas coupling.

FAA's Determination

    These helicopters have been approved by the aviation authority of 
Canada and are approved for operation in the United States. Pursuant to 
the FAA's bilateral agreement with Canada, Transport Canada, its 
technical representative, has notified the FAA of the unsafe condition 
described in the Transport Canada AD. The FAA is proposing this AD 
after evaluating all known relevant information and determining that an 
unsafe condition is likely to exist or develop on other helicopters of 
the same type design.

Related Service Information Under 1 CFR Part 51

    The FAA reviewed Bell Alert Service Bulletin 206-19-136, dated 
August 27, 2019, and Bell Alert Service Bulletin 206L-19-181, Revision 
A, dated August 29, 2019. This service information specifies procedures 
for replacing the affected nuts with the newly designed corrosion-
resistant nuts.
    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.

Other Related Service Information

    The FAA reviewed Air Comm Corporation Service Bulletin SB 206EC-
092619, Revision NC, dated September 26, 2019, which also specifies 
procedures for replacing the affected nuts with the newly designed 
corrosion-resistant nuts, but explains that affected helicopters 
equipped with Air Comm Corporation air conditioning systems installed 
under STC SH2750NM use the affected nut to attach a pulley onto the 
TRDS, which causes clearance issues for the nuts to be installed at the 
coupling. Therefore, this service bulletin specifies replacing the nut 
with a lower profile nut.
    The FAA also reviewed BHT-206-SI-2052. This service information 
specifies procedures to upgrade Model 206L-1 and 206L-3 helicopters to 
allow operations at an increased internal gross weight.

Proposed AD Requirements in This NPRM

    This proposed AD would require within 600 hours time-in-service 
(TIS) after the effective date of this AD, removing from service each 
affected nut, and installing a newly designed nut. This proposed AD 
would also require applying a specific torque and a torque stripe to 
each newly installed nut. This proposed AD would also require, within 
25 hours TIS after installation of each newly designed nut, inspecting 
the torque of each nut, and depending on the results of the inspection, 
this proposed AD would require further inspections and removing certain 
parts from service. Finally, this proposed AD would prohibit installing 
any affected nut on any on any TRDS Thomas coupling.

Differences Between This Proposed AD and the Transport Canada AD

    The Transport Canada AD requires compliance within 600 hours air 
time or within the next 24-months, whichever occurs first, whereas this 
proposed AD would require compliance within 600 hours TIS and an 
additional inspection at 25 hours TIS after installation of certain 
nuts.

Costs of Compliance

    The FAA estimates that this proposed AD would affect 1439 
helicopters of U.S. Registry. The FAA estimates that operators may 
incur the following costs in order to comply with this proposed AD. 
Labor costs are estimated at $85 per work-hour.
    Replacing each affected nut with the newly designed nut and 
applying torque and a torque stripe would take about 4 work-hours, and 
parts would cost about $75 for an estimated cost of $415 per nut 
replacement and $597,185 per nut replacement for the U.S. fleet.
    Replacing each TRDS Thomas coupling would take about 4 work-hours, 
and parts would cost about $4,000 for an estimated cost of $4,340 per 
TRDS Thomas coupling replacement.
    If required, inspecting the torque of each newly installed nut, and 
inspecting each TRDS Thomas coupling, each bolt, nut and washer for 
elongated holes and fretting on the fasteners would take about 0.5 
work-hours for an estimated cost of $43 per inspection.

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

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

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

[[Page 51041]]

Sec.  39.13  [Amended]

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

Bell Textron Canada Limited: Docket No. FAA-2021-0728; Project 
Identifier MCAI-2020-00656-R.

(a) Comments Due Date

    The FAA must receive comments on this airworthiness directive 
(AD) by October 29, 2021.

(b) Affected ADs

    None.

(c) Applicability

    This AD applies to Bell Textron Canada Limited Model 206, 206A, 
206A-1, 206B, 206B-1, 206L, 206L-1, 206L-3, and 206L-4 helicopters, 
certificated in any category, with nut part number (P/N) MS21042L4 
or P/N MS21042L5 installed on the tail rotor drive shaft (TRDS) disc 
pack (Thomas) couplings.
    Note 1 to paragraph (c): Helicopters with an OH-58A designation 
are Model 206A-1 helicopters.

(d) Subject

    Joint Aircraft Service Component (JASC) Code: 6510, Tail Rotor 
Drive Shaft.

(e) Unsafe Condition

    This AD was prompted by reports of cracked or missing nuts 
installed on the TRDS Thomas couplings. The FAA is issuing this AD 
to prevent failure or loss of a nut on the TRDS Thomas couplings. 
The unsafe condition, if not addressed, could result in loss of the 
tail rotor and subsequent loss of control of the helicopter.

(f) Compliance

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

(g) Required Actions

    (1) Within 600 hours time-in-service (TIS) after the effective 
date of this AD:
    (i) For helicopters that have not been modified by installing 
Supplemental Type Certificate (STC) SH2750NM:
    (A) Remove each nut P/N MS21042L4 installed on each TRDS Thomas 
coupling from service, and replace with nut P/N NAS9926-4L. The 
location of nut P/N NAS9926-4L is depicted in Detail A Figure 1 of 
Bell Alert Service Bulletin (ASB) 206-19-136, dated August 27, 2019 
(ASB 206-19-136) or Bell ASB 206L-19-181, Revision A, dated August 
29, 2019 (ASB 206L-19-181), as applicable to your model helicopter.
    (B) Apply a torque of 5.65 Nm (50 in lb) to each nut installed 
as required by paragraph (g)(1)(i)(A) of this AD, and apply a torque 
stripe using torque seal lacquer (C-049) or equivalent lacquer, as 
shown in Figure 2 of ASB 206-19-136 or ASB 206L-19-181, as 
applicable to your model helicopter.
    Note 2 to paragraph (g)(1)(i)(B): Torque stripes are referred to 
as witness marks in ASB 206-19-136 and ASB 206L-19-181.
    (ii) For Bell Textron Canada Limited Model 206, 206A, 206A-1, 
206B, 206B-1, and 206L helicopters that have been modified by 
installing STC SH2750NM and Model 206L-1, and 206L-3 helicopters 
that have been modified by installing STC SH2750NM but have not been 
modified by accomplishing Bell Service Instruction BHT-206-SI-2052, 
Revision 1, dated October 14, 2010 (BHT-206-SI-2052):
    (A) Remove each nut P/N MS21042L4 installed on each TRDS Thomas 
coupling from service, except for nuts P/N MS21042L4 installed on 
the forward short TRDS Thomas coupling, and replace with nut P/N 
NAS9926-4L. The location of nut P/N NAS9926-4L is depicted in Detail 
A Figure 1 of ASB 206-19-136 or ASB 206L-19-181 as applicable to 
your model helicopter.
    (B) Remove each nut P/N MS21042L4 installed on the forward short 
TRDS Thomas coupling from service and replace with nut P/N 90-132L4.
    (C) For each nut installed as required by paragraphs 
(g)(1)(ii)(A) and (B) of this AD, apply a torque of 5.65 Nm (50 in 
lb) to each nut and apply a torque stripe using torque seal lacquer 
(C-049) or equivalent lacquer, as shown in Figure 2 of ASB 206-19-
136 or ASB 206L-19-181, as applicable to your model helicopter.
    (iii) For Bell Textron Canada Limited Model 206L-1, and 206L-3 
helicopters that have been modified by installing STC SH2750NM and 
have been modified by accomplishing BHT-206-SI-2052:
    (A) Remove each nut P/N MS21042L4 installed on each TRDS Thomas 
coupling from service, except for nuts P/N MS21042L4 installed on 
the forward short TRDS Thomas coupling, and replace with nut P/N 
NAS9926-4L. The location of nut P/N NAS9926-4L is depicted in Detail 
A Figure 1 of ASB 206L-19-181.
    (B) Remove each nut P/N MS21042L4 installed on the forward short 
TRDS Thomas coupling from service and replace with nut P/N 90-132L4.
    (C) For each nut installed as required by paragraphs 
(g)(1)(iii)(A) and (B) of this AD, apply a torque of 5.65 Nm (50 in 
lb) to each nut, and apply a torque stripe using torque seal lacquer 
(C-049) or equivalent lacquer, as shown in Figure 2 of ASB 206L-19-
181.
    (iv) For Bell Textron Canada Limited Model 206L-4 helicopters 
that have been modified by installing STC SH2750NM:
    (A) Remove each nut P/N MS21042L4 installed on each TRDS Thomas 
coupling from service, except for nuts P/N MS21042L4 installed on 
the forward short TRDS Thomas coupling, and replace with nut P/N 
NAS9926-4L. The location of nut P/N NAS9926-4L is depicted in Detail 
A Figure 1 of ASB 206L-19-181.
    (B) Remove from service each nut P/N MS21042L5 installed on the 
forward short TRDS Thomas coupling and replace with nut P/N 90-
132L5.
    (C) For each nut installed as required by paragraphs 
(g)(1)(iv)(A) and (B) of this AD, apply a torque of 5.65 Nm (50 in 
lb) to each nut, and apply a torque stripe using torque seal lacquer 
(C-049) or equivalent lacquer, as shown in Figure 2 of ASB 206L-19-
181.
    (2) Within 25 hours TIS after installation of any nut P/N 
NAS9926-4L, P/N 90-132L4, or P/N 90-132L5, as required by paragraphs 
(g)(1)(i)(A), (ii)(A) and (B), (iii)(A) and (B), or (iv)(A) and (B) 
of this AD, apply a torque of 5.65 Nm (50 in lb) to each nut.
    (i) If the nut does not move, apply a torque stripe using torque 
seal lacquer (C-049) or equivalent lacquer, as shown in Figure 2 of 
ASB 206-19-136 or ASB 206L-19-181, as applicable to your model 
helicopter.
    (ii) If any nut moves, inspect each TRDS Thomas coupling and 
each bolt, nut, and washer for elongated holes and fretting on the 
fasteners. If any TRDS Thomas coupling has an elongated hole, remove 
the TRDS Thomas coupling from service. If any bolt, nut, or washer 
has any fretting, remove the affected part from service.
    (3) As of the effective date of this AD, do not install nut P/N 
MS21042L4 or MS21042L5 on any TRDS Thomas coupling.

(h) 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 (i)(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.

(i) Related Information

    (1) For more information about this AD, contact Matt Fuller, AD 
Program Manager, General Aviation & Rotorcraft Unit, Airworthiness 
Products Section, Operational Safety Branch, FAA, 10101 Hillwood 
Pkwy., Fort Worth, TX 76177; telephone (817) 222-5110; email 
matthew.fuller@faa.gov.
    (2) For service information identified in this AD, contact Bell 
Textron Canada Limited, 12,800 Rue de l'Avenir, Mirabel, Quebec J7J 
1R4, Canada; telephone 1-450-437-2862 or 1-800-363-8023; fax 1-450-
433-0272; email productsupport@bellflight.com; or at https://www.bellflight.com/support/contact-support. 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 Transport Canada AD 
CF-2020-15, dated May 13, 2020. You may view the Transport Canada AD 
on the internet at https://www.regulations.gov in the AD Docket.

    Issued on September 2, 2021.
Gaetano A. Sciortino,
Deputy Director for Strategic Initiatives, Compliance & Airworthiness 
Division, Aircraft Certification Service.
[FR Doc. 2021-19605 Filed 9-13-21; 8:45 am]
BILLING CODE 4910-13-P


