[Federal Register Volume 89, Number 193 (Friday, October 4, 2024)]
[Rules and Regulations]
[Pages 80734-80739]
From the Federal Register Online via the Government Publishing Office [www.gpo.gov]
[FR Doc No: 2024-22908]



[[Page 80734]]

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DEPARTMENT OF TRANSPORTATION

Federal Aviation Administration

14 CFR Part 39

[Docket No. FAA-2022-0600; Project Identifier AD-2021-01160-R; 
Amendment 39-22827; AD 2024-17-02]
RIN 2120-AA64


Airworthiness Directives; Bell Textron Inc. Helicopters

AGENCY: Federal Aviation Administration (FAA), DOT.

ACTION: Final rule.

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SUMMARY: The FAA is adopting a new airworthiness directive (AD) for all 
Bell Textron Inc. (Bell) Model 204B, 205A, 205A-1, 205B, and 210 
helicopters. This AD was prompted by an accident and incidents 
involving failure of the tail boom attachment structure. This AD 
requires inspecting the tail boom assembly hardware, replacing tail 
boom attachment hardware, greasing the bolt shanks, and inspecting 
torque. This AD also prohibits installing steel alloy nuts on any 
helicopter. The FAA is issuing this AD to address the unsafe condition 
on these products.

DATES: This AD is effective November 8, 2024.
    The Director of the Federal Register approved the incorporation by 
reference of a certain publication listed in this AD as of November 8, 
2024.

ADDRESSES: 
    AD Docket: You may examine the AD docket at regulations.gov under 
Docket No. FAA-2022-0600; 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 final rule, any comments received, and other 
information. The address for Docket Operations is U.S. Department of 
Transportation, Docket Operations, M-30, West Building Ground Floor, 
Room W12-140, 1200 New Jersey Avenue SE, Washington, DC 20590.
    Material Incorporated by Reference:
    <bullet> For Bell material identified in this AD, contact Bell 
Textron Inc., P.O. Box 482, Fort Worth, TX 76101; phone: (450) 437-2862 
or (800) 363-8023; fax: (450) 433-0272; email: 
<a href="/cdn-cgi/l/email-protection#2b5b59444f5e485f585e5b5b44595f6b494e47474d47424c435f05484446"><span class="__cf_email__" data-cfemail="fb8b89949f8e988f888e8b8b94898fbb999e97979d97929c938fd5989496">[email protected]</span></a>; website: bellflight.com/support/contact-support.
    <bullet> You may view this material 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.
    Other Related Material: For other material identified in this final 
rule, contact Bell Textron Inc., P.O. Box 482, Fort Worth, TX 76101; 
phone: (450) 437-2862 or (800) 363-8023; fax: (450) 433-0272; email: 
<a href="/cdn-cgi/l/email-protection#2c5c5e4348594f585f595c5c435e586c4e4940404a40454b4458024f4341"><span class="__cf_email__" data-cfemail="a3d3d1ccc7d6c0d7d0d6d3d3ccd1d7e3c1c6cfcfc5cfcac4cbd78dc0ccce">[email protected]</span></a>; website: bellflight.com/support/contact-support.

FOR FURTHER INFORMATION CONTACT: Michael Perrin, Aviation Safety 
Engineer, FAA, 1801 S Airport Road, Wichita, KS 67209; phone: (562) 
627-5362; email: <a href="/cdn-cgi/l/email-protection#7e33171d161f1b125014500e1b0c0c17103e181f1f50191108"><span class="__cf_email__" data-cfemail="afe2c6ccc7cecac381c581dfcaddddc6c1efc9cece81c8c0d9">[email protected]</span></a>.

SUPPLEMENTARY INFORMATION:

Background

    The FAA issued AD 2021-15-14, Amendment 39-21661 (86 FR 39942, July 
26, 2021) (AD 2021-15-14) for various restricted category helicopters. 
AD 2021-15-14 was prompted by an accident involving a Model UH-1B 
helicopter and two forced landings involving Model UH-1H and UH-1F 
helicopters, due to tail boom attachment structure failures. Each of 
the three events involved a failure of the upper left-hand (LH) tail 
boom attachment fitting, which is the most heavily loaded of the four 
tail boom attach points. The FAA issued AD 2021-15-14 to address 
fatigue cracking of tail boom attachment fittings, cap angles, 
longerons, and bolts.
    Due to their similarity to Model UH-1B, UH-1H, and UH-1F 
helicopters, the FAA determined that Bell Model 204B, 205A, 205A-1, 
205B, and 210 helicopters are also affected by the same unsafe 
condition and issued a notice of proposed rulemaking (NPRM) to propose 
the same actions as those required in AD 2021-15-14. The NPRM published 
in the Federal Register on June 7, 2022 (87 FR 34587) to amend 14 CFR 
part 39 and would have applied to Bell Model 204B, 205A, 205A-1, 205B, 
and 210 helicopters. In the NPRM, the FAA proposed to require revising 
the helicopter's existing rotorcraft flight manual to incorporate pre-
flight checks; removing excess paint and sealant and cleaning certain 
parts; and repetitively inspecting structural components that attach 
the tail boom to the fuselage. Depending on the inspection results, the 
FAA proposed to require repairing or replacing components or re-bonding 
the structure.
    Based on comments received on the NPRM, the FAA determined changes 
to the proposed required actions were necessary. Accordingly, the FAA 
issued a supplemental notice of proposed rulemaking (SNPRM) to amend 14 
CFR part 39 by adding an AD that would apply to all Bell Model 204B, 
205A, 205A-1, 205B, and 210 helicopters. The SNPRM published in the 
Federal Register on May 8, 2024 (89 FR 38846).
    In the SNPRM, for Bell Model 204B helicopters, the FAA proposed to 
require, with the tail boom assembly removed, removing the upper LH 
bolt from service and inspecting the bolt's associated attachment 
hardware and, depending on the inspection results, removing the 
associated nut from service. The FAA also proposed to require visually 
inspecting each bulkhead, bolt hole, attachment fitting, the three 
other nuts, the upper right-hand (RH) bolt, and two lower bolts, 
including the bolt shank and head radii. Depending on inspection 
results, the FAA proposed to require repairing or replacing an affected 
bulkhead or affected fitting, removing certain part-numbered nuts, 
removing any affected nut and its associated bolt from service, and 
removing any affected bolt from service.
    For Bell Model 205A, 205A-1, and 205B helicopters, the FAA proposed 
to require, with the tail boom assembly removed, removing the upper LH 
bolt from service and inspecting its associated barrel nut and retainer 
and, depending on the inspection results, removing barrel nut and 
retainer from service. The FAA also proposed to require visually 
inspecting each bulkhead, bolt hole, attachment fitting, the three 
other barrel nuts, associated retainers, the upper RH bolt, and two 
lower bolts, including the bolt shank and head radii. Depending on 
inspection results, the FAA proposed to require repairing or replacing 
an affected bulkhead or affected fitting, removing certain part-
numbered barrel nuts and retainers, removing any affected barrel nuts 
and its associated bolt from service, and removing any affected bolt 
from service.
    For Bell Model 210 helicopters, the FAA proposed to require, with 
the tail boom supported, removing the upper LH steel alloy barrel nut, 
retainer, and bolt from service and removing the countersunk washer and 
plain washers and replacing them with a new certain part-numbered 
nickel alloy barrel nut, new retainer, new bolt, an airworthy 
countersunk washer, and airworthy plain washers. The FAA also proposed 
to require visually inspecting the upper RH bolt and its associated 
hardware and, depending on the inspection results, removing the upper 
RH bolt and barrel nut from service. Additionally, the FAA proposed to 
require visually inspecting the two lower bolts and the associated 
barrel nuts and, depending on the inspection results, removing any 
affected barrel nut and its associated

[[Page 80735]]

bolt from service and removing any affected bolt from service.
    For all applicable helicopters, the FAA proposed to require, after 
the initial inspections have been completed, applying a coating of 
grease to each bolt shank only, installing the applicable hardware, and 
torquing each bolt. Thereafter, the FAA proposed to require inspecting 
the torque applied on each bolt to determine if the torque has 
stabilized and, depending on the results, replacing and inspecting 
certain tail boom attachment point hardware and repeating the torque 
inspections or applying torque stripes.
    Lastly, the FAA proposed to prohibit installing certain part-
numbered steel alloy nuts on Model 204B helicopters and certain part-
numbered steel alloy barrel nuts on Model 205A, 205A-1, 205B, and 210 
helicopters.

Discussion of Final Airworthiness Directive

Comments

    The FAA received comments on the SNPRM from Helicopter Maintenance 
Corporation. The commenter requested that the FAA revise the proposed 
AD to allow credit for previous compliance with the visual inspection 
of the tail boom attach points and bulkhead, replacement of affected 
hardware, and the recurring inspections involving removal of the tail 
boom. Helicopter Maintenance Corporation stated that aircraft that are 
in compliance with ASB 205-21-118 should only be obligated to comply 
with any differences between the AD and the alert service bulletin.
    Paragraph (f) of this AD requires compliance unless the actions 
have already been done. Therefore, where this AD requires actions 
without incorporating Bell Alert Service Bulletin (ASB) 210-21-15, 
Revision A, dated February 23, 2022 (ASB 210-21-15, Rev A), by 
reference, operators may take credit for those actions they if were 
done before the effective date of this AD. Also, where this AD requires 
actions in accordance with ASB 210-21-15, Rev A, operators may take 
credit for those actions only if they were done before the effective 
date of this AD using ASB 210-21-15, Rev A; this AD does not allow 
credit for those actions if previously done using the original release 
of ASB 210-21-15, (dated January 27, 2022). The FAA did not change this 
AD as a result of this comment.

Conclusion

    The FAA reviewed the relevant data, considered any comments 
received, and determined that air safety requires adopting this AD as 
proposed. Accordingly, the FAA is issuing this AD to address the unsafe 
condition on these products. Except for minor editorial changes, this 
AD is adopted as proposed in the SNPRM.

Material Incorporated by Reference Under 1 CFR Part 51

    The FAA reviewed Bell ASB 210-21-15, Rev A. This material specifies 
procedures for replacing the steel alloy barrel nuts with nickel alloy 
barrel nuts, inspecting and replacing the tail boom attachment 
hardware, stabilizing the tail boom attachment hardware torque, 
applying torque seals, and subsequently checking the torque.
    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.

Other Related Material

    The FAA also reviewed Bell ASB 205-21-118, Bell ASB 204B-21-75, and 
Bell ASB 205B-21-72, each Revision A and dated February 23, 2022. This 
material specifies the same procedures as ASB 210-21-15, Rev A.

Differences Between This AD and the Related Material

    The related material specifies checking torque, whereas this AD 
requires inspecting torque because that action is a maintenance action 
that must be performed by persons authorized under 14 CFR 43.3.
    When stabilizing the tail boom attachment hardware torque, the 
related material does not clearly specify actions for each time the 
torque is below the minimum limit during any torque stabilization 
inspection, whereas this AD requires replacing and inspecting certain 
tail boom attachment point hardware, stabilizing the torque of the 
replaced hardware set, and applying torque stripes.

Costs of Compliance

    The FAA estimates that this AD affects 62 (five Model 204B 
helicopters, fifty-three Model 205A, 205A-1, and 205B helicopters, and 
four Model 210 helicopters) of U.S. registry. Labor costs are estimated 
at $85 per work-hour. Based on these numbers, the FAA estimates the 
following costs to comply with this AD.
    For the initial requirements for Model 204B helicopters, inspecting 
or replacing up to four bolts (which includes applying a coating of 
grease), inspecting each bulkhead, inspecting each fitting and bolt 
hole, inspecting and stabilizing the torque, and applying torque 
stripes will take up to approximately 8.5 work-hours for an estimated 
labor cost of up to $723. The parts cost for an upper LH bolt will be 
approximately $196 and the parts cost for the other bolts will be 
approximately $89 per bolt. The parts cost for four new nuts will be 
approximately $680. The parts cost to apply torque stripes will be a 
nominal amount. The estimated cost for these actions will be up to 
approximately $1,866 per helicopter and $9,330 for the U.S. fleet.
    For the initial requirements for Model 205A, 205A-1, and 205B 
helicopters, replacing the four steel alloy barrel nuts with new nickel 
alloy barrel nuts, inspecting or replacing up to four bolts (which 
includes applying a coating of grease), inspecting each bulkhead, 
inspecting and stabilizing the torque, and applying torque stripes will 
take up to approximately 8.5 work-hours for an estimated labor cost of 
up to $723. The parts cost for the four new nickel alloy barrel nuts 
(including retainers) will be approximately $680. The parts cost for an 
upper LH bolt will be approximately $196 and the parts cost for the 
other bolts will be approximately $89 per bolt. The parts cost to apply 
torque stripes will be a nominal amount. The estimated cost for these 
actions will be up to approximately $1,866 per helicopter and $98,898 
for the U.S. fleet.
    For the initial requirements for Model 210 helicopters, replacing 
the four steel alloy barrel nuts with new nickel alloy barrel nuts, 
inspecting or replacing up to four bolts (which includes applying a 
coating of grease), inspecting and stabilizing the torque, and applying 
torque stripes will take up to approximately 8.5 work-hours for an 
estimated labor cost of up to $723. The parts cost for the four new 
nickel alloy barrel nuts (including retainers) will be approximately 
$680. The parts cost for an upper LH bolt will be approximately $196 
and the parts cost for the other bolts will be approximately $89 per 
bolt. The parts cost to apply torque stripes will be a nominal amount. 
The estimated cost for these actions will be up to approximately $1,866 
per helicopter and $7,464 for the U.S. fleet.
    For all applicable helicopters, inspecting the torque applied on 
each bolt will take approximately 1 work-hour for an estimated cost of 
$85 per helicopter and $5,270 for the U.S. fleet, per inspection cycle.
    For all applicable helicopters, replacing an upper LH bolt, 
stabilizing the torque, and applying a torque stripe will take up to 
approximately 5 work-hours. The parts cost for an upper LH bolt will be 
approximately $196 and the parts cost to apply a torque stripe will

[[Page 80736]]

be a nominal amount. The estimated cost for these actions will be up to 
approximately $621 per helicopter and $38,502 for the U.S. fleet, per 
replacement cycle. Inspecting one of the other bolts, stabilizing the 
torque, and applying a torque stripe will take up to approximately 3.5 
work-hours for an estimated cost of $298 per other bolt and $18,476 for 
the U.S. fleet per other bolt per inspection cycle. If required, 
replacing a bolt following that inspection will take a minimal amount 
of additional time and the parts cost will be approximately $89.
    If required as a result of failing any torque inspection required 
by this AD, visually inspecting a nut or a barrel nut, replacing a 
bolt, stabilizing the torque, and applying a torque stripe will take up 
to approximately 5.5 work-hours per failed hardware set. The parts cost 
for an upper LH bolt will be approximately $196 and the parts cost for 
the other bolts will be approximately $89 per bolt. The parts cost to 
apply a torque stripe will be a nominal amount. The estimated cost for 
these actions will be $664 (upper LH bolt) or $557 (other bolts), per 
failed hardware set. If required, replacing a nut following that 
inspection will take a minimal amount of additional time and the parts 
cost for a nut will be approximately $89 per nut. If required, 
replacing a barrel nut following that inspection will take a minimal 
amount of additional time and a parts cost of approximately $173 per 
barrel nut.
    The corrective action that may be needed as a result of the 
bulkhead inspection could vary significantly from helicopter to 
helicopter. The FAA has no data to determine the costs to accomplish 
the corrective action or the number of helicopters that may require 
corrective action.

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

    This AD will not have federalism implications under Executive Order 
13132. This AD will 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 above, I certify that this AD:
    (1) Is not a ``significant regulatory action'' under Executive 
Order 12866,
    (2) Will not affect intrastate aviation in Alaska, and
    (3) Will 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 Amendment

    Accordingly, under the authority delegated to me by the 
Administrator, the FAA amends 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 adding the following new airworthiness 
directive:

2024-17-02 Bell Textron Inc.: Amendment 39-22827; Docket No. FAA-
2022-0600; Project Identifier AD-2021-01160-R.

(a) Effective Date

    This airworthiness directive (AD) is effective November 8, 2024.

(b) Affected ADs

    None.

(c) Applicability

    This AD applies to Bell Textron Inc. Model 204B, 205A, 205A-1, 
205B, and 210 helicopters, certificated in any category.

(d) Subject

    Joint Aircraft System Component (JASC) 5302, Rotorcraft Tail 
Boom.

(e) Unsafe Condition

    This AD was prompted by an accident and incidents involving 
failure of the tail boom attachment structure. The FAA is issuing 
this AD to address fatigue cracking of tail boom attachment 
fittings, cap angles, longerons, and bolts. The unsafe condition, if 
not addressed, could result in separation of the tail boom from the 
helicopter and subsequent loss of control of the helicopter.

(f) Compliance

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

 (g) Allowable Torque Values (in-lbs)

----------------------------------------------------------------------------------------------------------------
    Tail boom attachment point         Model 204B       Model 205A/205A-1       Model 205B         Model 210
----------------------------------------------------------------------------------------------------------------
Upper left-hand bolt.............            570-610             1000-1200          1000-1200          1300-1600
Upper right-hand bolt............            360-380             1000-1200          1000-1200          1000-1200
Lower left-hand bolt.............            360-380               400-430            400-430            400-430
Lower right-hand bolt............            360-380               400-430            400-430            400-430
----------------------------------------------------------------------------------------------------------------

(h) Required Actions

    (1) Within 300 hours time-in-service (TIS) or 90 days after the 
effective date of this AD, whichever occurs first, accomplish the 
actions required by paragraphs (h)(1)(i), (ii), or (iii) of this AD 
as applicable to your model helicopter. For purposes of this AD, the 
word ``new'' is defined as having zero total hours TIS.
    (i) For Model 204B helicopters, accomplish the actions required 
by paragraphs (h)(1)(i)(A) through (C) of this AD.
    (A) With the tail boom assembly removed, remove the upper left-
hand (LH) tail boom attachment bolt (bolt) from service and inspect 
its associated tail boom attachment nut (nut) for mechanical damage, 
corrosion, a crack, damaged threads, and wear, and to determine 
whether it is a steel alloy part number (P/N) NAS679A, NAS1291, or 
MS21042. If there is any mechanical damage, corrosion, a crack, a 
damaged thread, or wear, or if nut P/N NAS679A, NAS1291, or MS21042 
is installed, before further flight, remove the nut from service.
    (B) Visually inspect each bulkhead (FS 195.00 and FS 195.03) and 
the bolt holes for mechanical damage, corrosion, and cracks; 
visually inspect each attachment fitting for

[[Page 80737]]

mechanical damage, corrosion, cracks, and loose fasteners; determine 
if any of the three other nuts are a steel alloy P/N NAS679A, 
NAS1291, or MS21042; and visually inspect the other three nuts, the 
upper right-hand (RH) bolt, and two lower bolts for mechanical 
damage, corrosion, cracks, damaged threads, and wear, including the 
bolt shank and head radii of the bolts for a damaged thread, wear, 
and mechanical damage.
    (1) If there is any mechanical damage, corrosion, or cracks on 
any bulkhead (FS 195.00 or FS 195.03), or any mechanical damage, 
corrosion, or cracks on any bolt holes, or if there is any 
mechanical damage, corrosion, cracks, or loose fasteners on any 
attachment fitting, before further flight, repair or replace the 
affected bulkhead or the affected attachment fitting, as 
appropriate, in accordance with FAA-approved procedures.
    (2) If there is any mechanical damage, corrosion, a crack, a 
damaged thread, or wear on any nut, or if nut P/N NAS679A, NAS1291, 
or MS21042 is installed, before further flight, remove the affected 
nut from service. If there is a crack on any nut, before further 
flight, also remove its associated bolt from service.
    (3) If there is any mechanical damage, corrosion, a crack, a 
damaged thread, or wear on the on the upper RH bolt or two lower 
bolts, which includes the bolt shank or head radii, before further 
flight, remove the affected bolt from service.
    (C) Apply a coating of Aeriol ThixO #2 (3810-0) or Aeriol ThixO 
SYN (3820-0) aviation grease to each bolt shank only. Install the 
hardware set of each tail boom attachment point (nickel alloy nut P/
N 90-132L7 or 90-132L6, as applicable to the affected tail boom 
attachment point, new upper LH bolt P/N NAS627-21, upper RH and two 
lower bolts P/N NAS626-20, countersunk washer, and plain washers). 
Torque each bolt by using the torque value information identified in 
paragraph (g) of this AD.
    (ii) For Model 205A, 205A-1, and 205B helicopters, accomplish 
the actions required by paragraphs (h)(1)(ii)(A) through (C) of this 
AD.
    (A) With the tail boom assembly removed, remove the upper LH 
bolt from service and inspect its associated tail boom attachment 
barrel nut (barrel nut) and retainer for mechanical damage, 
corrosion, a crack, damaged threads, and wear, and to determine 
whether it is a steel alloy barrel nut P/N NAS577B8A. If there is 
any mechanical damage, corrosion, a crack, a damaged thread, or 
wear, or if barrel nut P/N NAS577B8A is installed, before further 
flight, remove the barrel nut and its associated retainer from 
service.
    (B) Visually inspect each bulkhead (BS 17.31 and FS 243.89) and 
the bolt holes for mechanical damage, corrosion, and cracks; 
visually inspect each attachment fitting for mechanical damage, 
corrosion, cracks, and loose fasteners; determine if any of the 
three other barrel nuts are steel alloy P/N NAS577B8A or P/N 
NAS577B6A; and visually inspect the other three barrel nuts and the 
associated retainers, the upper RH bolt, and two lower bolts for 
mechanical damage, corrosion, cracks, damaged threads, and wear, 
including the bolt shank and head radii of the bolts for a damaged 
thread, wear, and mechanical damage.
    (1) If there is any mechanical damage, corrosion, or cracks on 
any bulkhead (BS 17.31 or FS 243.89), or any mechanical damage, 
corrosion, or cracks on any bolt holes, or if there is any 
mechanical damage, corrosion, cracks, or loose fasteners on any 
attachment fitting, before further flight, repair or replace the 
affected bulkhead or the affected attachment fitting, as 
appropriate, in accordance with FAA-approved procedures.
    (2) If there is any mechanical damage, corrosion, a crack, a 
damaged thread, or wear on any barrel nut or retainer, or if barrel 
nut P/N NAS577B8A or NAS577B6A is installed, before further flight, 
remove the affected barrel nut and retainer (as a pair) from 
service. If there is a crack on any nut, before further flight, also 
remove its associated bolt from service.
    (3) If there is any mechanical damage, corrosion, a crack, a 
damaged thread, or wear on the upper RH bolt or two lower bolts, 
which includes the bolt shank or head radii, before further flight, 
remove the affected bolt from service.
    (C) Apply a coating of Aeriol ThixO #2 (3810-0) or Aeriol ThixO 
SYN (3820-0) aviation grease to each bolt shank only. Install the 
hardware set of each tail boom attachment point (nickel alloy barrel 
nut P/N NAS577C6A or P/N NAS577C8A and retainer P/N NAS578C6A or P/N 
NAS578C8A, as applicable to the affected tail boom attachment point, 
new upper LH bolt P/N NAS628-22, upper RH and two lower bolts P/N 
NAS628-22 or NAS626-18, as applicable to the affected tail boom 
attachment point, countersunk washer, and plain washers). Torque 
each bolt by using the torque value information identified in 
paragraph (g) of this AD.
    (iii) For Model 210 helicopters, accomplish the actions required 
by paragraphs (h)(1)(iii)(A) through (C) of this AD.
    (A) With the tail boom supported, remove the upper LH bolt, and 
the steel alloy barrel nut P/N NAS577B9A, including the retainer, 
from service. Remove the countersunk washer, and plain washers, and 
install new nickel alloy barrel nut P/N NAS577C9A, new retainer P/N 
NAS578C9A, airworthy countersunk washer, airworthy plain washers, 
and a new bolt in accordance with the Accomplishment Instructions, 
Part I, paragraphs 5 through 7 of Bell Alert Service Bulletin (ASB) 
210-21-15, Revision A, dated February 23, 2022 (ASB 210-21-15, Rev 
A).
    (B) Remove the upper RH bolt, steel alloy barrel nut P/N 
NAS577B8A, countersunk washer, and plain washers. Visually inspect 
the upper RH bolt for any corrosion, damaged threads, wear, and 
fatigue cracking. If the upper RH bolt has any corrosion, damaged 
threads, wear, or fatigue cracking, before further flight, remove 
the upper RH bolt from service. Visually inspect the removed barrel 
nut for cracking. If there is any cracking in the barrel nut, before 
further flight, remove the upper RH bolt from service. Regardless of 
the result of the upper RH steel alloy barrel nut inspection, 
replace the barrel nut with a new nickel alloy barrel nut P/N 
NAS577C8A and new retainer P/N NAS578C8A. Install a new upper RH 
bolt or reinstall the existing upper RH bolt (if no cracks in the 
barrel nut, and no corrosion, damaged threads, wear, or fatigue 
cracking in the bolt were identified), by following the 
Accomplishment Instructions, part I, paragraphs 11 and 12, including 
the caution above paragraph 11, of ASB 210-21-15, Rev A.
    (C) Remove one of the lower bolts, its lower steel alloy barrel 
nut P/N NAS577B6A, countersunk washer, and plain washers. Visually 
inspect that lower bolt for any corrosion, damaged threads, wear, 
and fatigue cracking. If the lower bolt has any corrosion, damaged 
threads, wear, or fatigue cracking, before further flight, remove 
the lower bolt from service. Visually inspect the removed lower 
barrel nut for cracking. If there is any cracking in the lower 
barrel nut, before further flight, remove the lower bolt from 
service. Regardless of the result of that lower steel alloy barrel 
nut inspection, replace the barrel nut with a new nickel alloy 
barrel nut P/N NAS577C6A and new retainer P/N NAS578C6A. Install a 
new lower bolt or reinstall the existing lower bolt (if no cracks in 
the barrel nut, and no corrosion, damaged threads, wear, or fatigue 
cracking in the bolt were identified), by following the 
Accomplishment Instructions, part I, paragraphs 16 through 17, 
including the caution above paragraph 16, of ASB 210-21-15, Rev A. 
Repeat the actions required by this paragraph for the other lower 
attachment point.
    (2) After accumulating 1 hour TIS, but not to exceed 5 hours 
TIS, after accomplishing the actions required by paragraph (h)(1) of 
this AD, using the torque value information identified in paragraph 
(g) of this AD applicable to your model helicopter, inspect the 
torque applied on each bolt. Thereafter, repeat the torque 
inspection of each bolt after accumulating 1 hour TIS, but not to 
exceed 5 hours TIS, to determine if the torque has stabilized. Do 
not exceed three torque inspections total for each bolt and 
accomplish the actions required by paragraphs (h)(2)(i) and (ii) of 
this AD.
    (i) If the torque on a bolt is below the minimum allowable 
torque limit as a result of any instance of the torque inspection or 
if after three torque inspection attempts, the torque on any bolt 
has not stabilized, before further flight, accomplish the actions 
required by paragraphs (h)(2)(i)(A) and (B) of this AD.
    (A) Remove the hardware set of one failed tail boom attachment 
point (nut, bolt, countersunk washer, and plain washers for Model 
204B helicopters, and barrel nut, bolt, retainer, countersunk 
washer, and plain washers for Model 205A, 205A-1, 205B, and 210 
helicopters). For Model 204B helicopters, remove the nut from 
service and for Model 205A, 205A-1, 205B, and 210 helicopters, 
remove the barrel nut and retainer from service as applicable to the 
affected tail boom attachment point. Visually inspect the removed 
bolt for any corrosion, damaged threads, wear, and fatigue cracking. 
If the bolt has any corrosion, a damaged thread, wear, or fatigue 
cracking, before further flight, remove the bolt from service.
    (B) Apply a coating of Aeriol ThixO #2 (3810-0) or Aeriol ThixO 
SYN (3820-0)

[[Page 80738]]

aviation grease to the bolt shank only. Install a new bolt or 
reinstall the existing bolt (if no corrosion, damaged threads, wear, 
or fatigue cracking in the bolt were identified) and the hardware 
set of the affected tail boom attachment point (new nut P/N 90-132L6 
or 90-132L7, countersunk washer, and plain washers for Model 204B 
helicopters, and new nickel alloy barrel nut P/N NAS577C6A, 
NAS577C8A or P/N NAS577C9A and new retainer P/N NAS578C6A, 
NAS578C8A, or P/N NAS577C9A, countersunk washer, and plain washers 
for Model 205A, 205A-1, 205B, and 210 helicopters), as applicable to 
the affected tail boom attachment point. Torque the bolt by using 
the torque value information identified in paragraph (g) of this AD. 
Repeat the actions required by paragraphs (h)(2)(i)(A) and (B) of 
this AD for each failed tail boom attachment point, one hardware set 
at a time. Then repeat the actions required by paragraph (h)(2) of 
this AD just for each newly installed or reinstalled bolt until the 
torque for all four tail boom attachment points stabilize.
    (ii) If the torque for all four tail boom attachment points has 
stabilized, before further flight, apply a torque stripe to all four 
bolts.
    (3) Within 600 hours TIS or 12 months, whichever occurs first 
after applying torque stripes to all four bolts as required by 
paragraph (h)(2)(ii) of this AD, and thereafter within intervals not 
to exceed 600 hours TIS or 12 months, whichever occurs first, 
inspect the torque applied on each bolt using the torque value 
information identified in paragraph (g) of this AD, as applicable to 
your model helicopter. If the torque on any bolt is below the 
minimum allowable torque limit, accomplish the actions required by 
paragraphs (h)(3)(i) and (ii) of this AD.
    (i) Before further flight, remove the hardware set of one failed 
tail boom attachment point (nut, bolt, countersunk washer, and plain 
washers for Model 204B helicopters, and barrel nut, retainer, bolt, 
countersunk washer, and plain washers for Model 205A, 205A-1, 205B, 
and 210 helicopters) and then accomplish the actions required by 
paragraphs (h)(3)(i)(A), (B), or (C) of this AD as applicable to 
your model helicopter.
    (A) For Model 204B helicopters, visually inspect the removed nut 
for cracking, corrosion, and loss of tare torque. If the nut has any 
cracking, corrosion, or loss of tare toque, before further flight, 
remove the nut from service and replace with a new nut P/N 90-132L7 
or 90-132L6 as applicable to the tail boom attachment point. 
Regardless of the result of the nut inspection, remove the bolt from 
service and replace it with a new bolt by applying a coating of 
Aeriol ThixO #2 (3810-0) or Aeriol ThixO SYN (3820-0) aviation 
grease to the bolt shank only, and install the hardware set of the 
tail boom attachment point (nut, bolt, and countersunk washer, and 
plain washers). Torque each bolt by using the torque value 
information identified in paragraph (g) of this AD. Repeat the 
actions required by this paragraph for each failed tail boom 
attachment point, one hardware set at a time.
    (B) For Model 205A, 205A-1, and 205B helicopters, visually 
inspect the removed barrel nut for cracking, corrosion, and loss of 
tare torque. If the barrel nut has any cracking, corrosion, or loss 
of tare toque, before further flight, remove the barrel nut and 
retainer from service and replace them with a new nickel alloy 
barrel nut P/N NAS577C6A, or NAS577C8A, and new retainer P/N 
NAS578C6A, or NAS578C8A, with the P/N of the new nickel alloy barrel 
nut and the P/N of the new retainer being as applicable to the 
affected tail boom attachment point. Regardless of the result of the 
barrel nut inspection, remove the bolt from service and replace it 
with a new bolt. Apply a coating of Aeriol ThixO #2 (3810-0) or 
Aeriol ThixO SYN (3820-0) aviation grease to each bolt shank only. 
Install the hardware set of each tail boom attachment point (nickel 
alloy barrel nut, retainer, bolt, countersunk washer, and plain 
washers). Torque each bolt by using the torque value information 
identified in paragraph (g) of this AD. Repeat the actions required 
by this paragraph for each failed tail boom attachment point, one 
hardware set at a time.
    (C) For Model 210 helicopters, visually inspect the removed 
barrel nut for cracking, corrosion, and loss of tare torque. If the 
barrel nut has any cracking, corrosion, or loss of tare toque, 
before further flight, remove the barrel nut and retainer from 
service and replace them with a new nickel alloy barrel nut P/N 
NAS577C6A, NAS577C8A, or NAS577C9A, and new retainer P/N NAS578C6A, 
NAS578C8A, or NAS578C9A, with the P/N of the new nickel alloy barrel 
nut and the P/N of the new retainer being as applicable to the 
affected tail boom attachment point. Regardless of the result of the 
barrel nut inspection, remove the bolt from service and replace it 
with a new bolt, apply a coating of Aeriol ThixO #2 (3810-0) or 
Aeriol ThixO SYN (3820-0) aviation grease to each bolt shank only, 
and torque each bolt by using the torque value information 
identified in paragraph (g) of this AD. Repeat the actions required 
by this paragraph for each failed tail boom attachment point, one 
hardware set at a time.
    (ii) After accumulating 1 hour TIS, but not to exceed 5 hours 
TIS after accomplishing the actions required by paragraph (h)(3)(i) 
of this AD, using the torque value information identified in 
paragraph (g) of this AD as applicable to your model helicopter, 
inspect the torque applied on each newly installed bolt. Thereafter, 
repeat the torque inspection of those bolts after accumulating 1 
hour TIS, but not to exceed 5 hours TIS, to determine if the torque 
has stabilized. Do not exceed three torque inspections total for 
those bolts and accomplish the actions required by paragraphs 
(h)(2)(i) and (ii) of this AD.
    (4) Within 5,000 hours TIS or 5 years after accomplishing the 
actions required by paragraph (h)(1) of this AD, whichever occurs 
first, and thereafter within intervals not to exceed 5,000 hours TIS 
or 5 years, whichever occurs first, accomplish the actions required 
by paragraphs (h)(4)(i) and (ii) of this AD.
    (i) Accomplish the actions required by paragraphs (h)(1)(i), 
(ii), or (iii) of this AD, as applicable to your model helicopter.
    (ii) After accumulating 1 hour TIS, but not to exceed 5 hours 
TIS after accomplishing the actions required by paragraph (h)(4)(i) 
of this AD, using the torque value information identified in 
paragraph (g) of this AD as applicable to your model helicopter, 
inspect the torque applied on each bolt. Thereafter, repeat the 
torque inspection of those bolts after accumulating 1 hour TIS, but 
not to exceed 5 hours TIS, to determine if the torque has 
stabilized. Do not exceed three torque inspections total for those 
bolts and accomplish the actions required by paragraphs (h)(2)(i) 
and (ii) of this AD.
    (5) As of the effective date of this AD, do not install the 
following parts identified in paragraphs (h)(5)(i) and (ii) of this 
AD on any helicopter.
    (i) For Model 204B helicopters: steel alloy nut P/N NAS679A, 
NAS1291, or MS21042.
    (ii) For Model 205A, 205A-1, 205B, and 210 helicopters: steel 
alloy barrel nut P/N NAS577B9A, P/N NAS577B8A, or P/N NAS577B6A.

(i) Special Flight Permit

    A one-time special flight permit may be issued in accordance 
with 14 CFR 21.197 and 21.199 in order to fly to a maintenance area 
to perform the required actions in this AD.

(j) Alternative Methods of Compliance (AMOCs)

    (1) The Manager, Central Certification 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 certification office, send it to the 
attention of the person identified in paragraph (k) of this AD. 
Information may be emailed to <a href="/cdn-cgi/l/email-protection#eaaba7a5a9aa8c8b8bc48d859c"><span class="__cf_email__" data-cfemail="4504080a06052324246b222a33">[email protected]</span></a>.
    (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.

(k) Related Information

    For more information about this AD, contact Michael Perrin, 
Aviation Safety Engineer, FAA, 1801 S Airport Road, Wichita, KS 
67209; phone: (562) 627-5362; email: <a href="/cdn-cgi/l/email-protection#f1bc98929990949ddf9bdf81948383989fb1979090df969e87"><span class="__cf_email__" data-cfemail="3e73575d565f5b521054104e5b4c4c57507e585f5f10595148">[email protected]</span></a>.

(l) Material Incorporated by Reference

    (1) The Director of the Federal Register approved the 
incorporation by reference of the material listed in this paragraph 
under 5 U.S.C. 552(a) and 1 CFR part 51.
    (2) You must use this material as applicable to do the actions 
required by this AD, unless the AD specifies otherwise.
    (i) Bell Alert Service Bulletin 210-21-15, Revision A, dated 
February 23, 2022.
    (ii) [Reserved]
    (3) For Bell material identified in this AD, contact Bell 
Textron Inc., P.O. Box 482, Fort Worth, TX 76101; phone: (450) 437-
2862 or (800) 363-8023; fax: (450) 433-0272; email: 
<a href="/cdn-cgi/l/email-protection#dbaba9b4bfaeb8afa8aeababb4a9af9bb9beb7b7bdb7b2bcb3aff5b8b4b6"><span class="__cf_email__" data-cfemail="a5d5d7cac1d0c6d1d6d0d5d5cad7d1e5c7c0c9c9c3c9ccc2cdd18bc6cac8">[email protected]</span></a>; website: bellflight.com/support/contact-support.
    (4) You may view this material at the FAA, Office of Regional 
Counsel, Southwest Region, 10101 Hillwood Pkwy., Fort Worth, TX 
76177. For information on the availability

[[Page 80739]]

of this material at the FAA, call: (817) 222-5110.
    (5) You may view this material at the National Archives and 
Records Administration (NARA). For information on the availability 
of this material at NARA, visit www.archives.gov/federal-register/cfr/ibr-locations or email <a href="/cdn-cgi/l/email-protection#294f5b0740475a594c4a5d4046476947485b48074e465f"><span class="__cf_email__" data-cfemail="1c7a6e3275726f6c797f687573725c727d6e7d327b736a">[email protected]</span></a>.

    Issued on September 27, 2024.
Victor Wicklund,
Deputy Director, Compliance & Airworthiness Division, Aircraft 
Certification Service.
[FR Doc. 2024-22908 Filed 10-3-24; 8:45 am]
BILLING CODE 4910-13-P


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