[Federal Register Volume 89, Number 90 (Wednesday, May 8, 2024)]
[Proposed Rules]
[Pages 38846-38852]
From the Federal Register Online via the Government Publishing Office [www.gpo.gov]
[FR Doc No: 2024-09572]


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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]
RIN 2120-AA64


Airworthiness Directives; Bell Textron Inc., Helicopters

AGENCY: Federal Aviation Administration (FAA), DOT.

ACTION: Supplemental notice of proposed rulemaking (SNPRM).

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SUMMARY: The FAA is revising a notice of proposed rulemaking (NPRM) 
that would have applied to all Bell Textron Inc., 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 action revises the NPRM by changing the proposed required actions 
and adding a special flight permit limitation. The FAA is proposing 
this airworthiness directive (AD) to address the unsafe condition on 
these products. Since these actions would impose an additional burden 
over those in the NPRM, the agency is requesting comments on this 
SNPRM.

DATES: The FAA must receive comments on this SNPRM by June 24, 2024.

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 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.
    AD Docket: You may examine the AD docket at regulations.gov by 
searching for and locating 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 the NPRM, this SNPRM, 
any comments received, and other information. The street address for 
Docket Operations is listed above.
    Material Incorporated by Reference:
     For Bell material, 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 [email protected]; website: 
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.
    Other Related Service Information: For other service information 
identified in this SNPRM, 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 [email protected]; 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: [email protected].

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 the ADDRESSES section. Include ``Docket No. FAA-2022-0600; 
Project Identifier AD-2021-01160-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 again revise 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 
regulations.gov, including any personal information you provide. The 
agency will also post a report summarizing each substantive verbal 
contact received about this SNPRM.

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 SNPRM 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 SNPRM, it is important that you clearly designate 
the

[[Page 38847]]

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 SNPRM. Submissions containing CBI should 
be sent to Michael Perrin, Aviation Safety Engineer, FAA, 1801 S 
Airport Road, Wichita, KS 67209; phone: (562) 627-5362; email: 
[email protected]. 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 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 at 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 the Model UH-1B, UH-1H, and UH-1F 
helicopters, the FAA determined that Bell Textron Inc., Model 204B, 
205A, 205A-1, 205B, and 210 helicopters are also affected by the same 
unsafe condition and issued an 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 Textron Inc., Model 204B, 205A, 205A-1, 
205B, and 210 helicopters. The NPRM proposed to require revising the 
helicopter's existing rotorcraft flight manual (RFM) to incorporate 
pre-flight checks; removing excess paint and sealant, and cleaning 
certain parts; and repetitive inspections of structural components that 
attach the tail boom to the fuselage. Depending on the inspection 
results, the NPRM proposed to require repairing or replacing 
components, or re-bonding the structure.

Actions Since the NPRM Was Issued

    Since the FAA issued the NPRM, the FAA has determined changes to 
the proposed required actions are necessary, primarily based on 
comments received from several commenters and additional review. The 
FAA has also determined to require a special flight permit limitation 
as proposed in this SNPRM.

Comments

    The FAA received comments from four commenters. The following 
discussion presents the comments received on the NPRM and the FAA's 
response.

Requests To Withdraw the NPRM

    Request: Delta Helicopters Ltd. (DHL) and Remote Helicopters Ltd. 
(RHL) stated that because Bell service information and established 
maintenance programs already provide the needed requirements to address 
the unsafe condition, the proposed AD is not necessary. Additionally, 
an individual commenter stated the proposed requirements will not 
prevent a sudden failure and stated that daily nut and bolt 
inspections, replacement of bolts and nuts at scheduled intervals, and 
maintaining proper torque would be just as effective as the 
requirements proposed in the NPRM.
    DHL stated that although damage does occur, sudden failures will 
not occur unless the helicopter is being operated outside of its 
capabilities and not being inspected properly as already prescribed by 
Bell in related alert service bulletins (ASBs). RHL stated that the 
proposed requirements in the NPRM are not necessary because properly 
accomplishing the service information from Bell and operating the 
helicopter within the appropriate parameters are sufficient. The FAA 
infers that these commenters are requesting that the FAA withdraw the 
NPRM.
    FAA Response: The FAA disagrees. While an operator may incorporate 
into its maintenance program the inspections in the manufacturer's 
service bulletins referenced by the commenters, not all operators are 
required to do so. In order for these inspections to become mandatory, 
and to correct the unsafe conditions identified in the NPRM, the FAA 
must issue an AD.
    Request: DHL, RHL, and one individual commenter each stated that 
the restricted category helicopters and the Bell Textron Inc., Model 
204 and 205 helicopters have significant dissimilarities. DHL stated 
that the comparison between restricted category and Bell Textron Inc., 
Model 204B and 205A-1 helicopters is not accurate, and the Model 205 
structure has more in common with the structure of a Model 212 
helicopter.
    RHL stated that the tail boom inspection for the Model UH-1 
helicopter is more difficult because of lack of access to the 
inspection areas. Accordingly, RHL stated that lack of access to the 
inspection areas is not a problem for Bell Textron Inc., Model 205 
helicopters, and because of this, the inspection areas for these 
helicopters are inspected on a regular basis.
    Additionally, one individual commenter stated the structural design 
of the tail boom and the fuselage attachment structure is different 
when comparing Model UH helicopters to Bell Textron Inc., Model 205A, 
205A-1, 205B, and 210 helicopters, and that these helicopters are more 
robust than the Model UH helicopter. The individual commenter also 
stated the failures mentioned in the NPRM occurred only on Model UH 
helicopters used during heli-logging, and heavy lift activities, but 
that commenter has never seen these failures during heavy lift 
activities in the Bell Textron Inc., Model 205A-1 helicopter. Finally, 
the individual commenter stated the proposed AD is unwarranted and 
without basis to include the Bell Textron Inc., Model 205A, 205A-1, 
205B, and 210 helicopters in the applicability as they are closer in 
similarity to the Bell Textron Inc., Model 212 helicopter. The FAA 
infers that these commenters are requesting that the FAA withdraw the 
NPRM.
    FAA Response: The FAA disagrees. An examination of the structures 
of both the Model UH-1 helicopters and the Bell Textron Inc., Model 204 
and 205 helicopters indicated no significant differences between the 
commercial and military model helicopters. Furthermore, there have been 
reported tail boom attachment failures involving the Bell Textron Inc., 
Model 205 helicopter. Additionally, performing heavy lift operations 
such as logging could accelerate failures in the tail boom attachment 
region. The FAA expects that the number of tail boom attachment 
failures will increase over time and will also include those aircraft 
not involved in heavy lift operations.

Request for Changes to the Required Actions

    Request: DHL commenter stated that stripping paint is not necessary 
to detect damage during routine maintenance.
    FAA Response: The FAA agrees and has revised this SNPRM 
accordingly.
    Request: One individual commenter stated inspection requirements 
are part of the Instructions for Continued Airworthiness and should not 
be included in a flight manual. The individual commenter stated a 
mandatory inspection is a stand-alone inspection and is not related to 
the operation of an aircraft, which is the main reason for a flight 
manual. Furthermore, the commenter stated

[[Page 38848]]

maintenance personnel would not review or reference a flight manual for 
inspection requirements.
    FAA Response: The FAA agrees and has revised this proposed AD 
accordingly by removing the requirement of revising the rotorcraft 
flight manual from the required actions.

Comment Regarding an Alternative Method of Compliance (AMOC) Request

    Request: One individual commenter requested the ability to submit a 
request for an AMOC for the tail boom sensor supplemental type 
certificate.
    FAA Response: The FAA agrees that operators may request approval of 
an AMOC under the provisions of paragraph (j) of this SNPRM.

FAA's Determination

    The FAA is proposing this AD after determining the unsafe condition 
described previously is likely to exist or develop in other products of 
the same type design. Certain changes described above expand the scope 
of the NPRM. As a result, it is necessary to reopen the comment period 
to provide additional opportunity for the public to comment on this 
SNPRM.

Related Service Information Under 1 CFR Part 51

    The FAA reviewed Bell Alert Service Bulletin (ASB) 210-21-15, 
Revision A, dated February 23, 2022 (ASB 210-21-15, Rev A). This 
service information 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 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 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 
service information specifies the same procedures as ASB 210-21-15, Rev 
A.

Proposed AD Requirements in This SNPRM

    This proposed AD would require for Bell Textron Inc., Model 204B 
helicopters, with the tailboom assembly removed, removing the upper 
left-hand (LH) bolt from service and inspecting the bolt's associated 
attachment hardware, and depending on the inspection results, removing 
the associated nut from service. This proposed AD would also require 
visually inspecting each bulkhead, bolt hole, attachment fitting, the 
three other nuts, the upper right-hand bolt, and two lower bolts, 
including the bolt shank and head radii. Depending on inspection 
results, this proposed AD would 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.
    This proposed AD would require for Bell Textron Inc., Model 205A, 
205A-1, and 205B helicopters, 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. This proposed AD would 
also require visually inspecting each bulkhead, bolt hole, attachment 
fitting, the three other barrel nuts, associated retainers, the upper 
right-hand bolt, and two lower bolts, including the bolt shank and head 
radii. Depending on inspection results, this proposed AD would 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.
    This proposed AD would require for Bell Textron Inc., Model 210 
helicopters, with the tail boom supported, removing the upper LH steel 
alloy barrel nut, retainer, and bolt from service. This proposed AD 
would also require 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. This proposed AD would also 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, this proposed AD would 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 bolt from service, and removing any affected bolt 
from service.
    Additionally, this proposed AD would require for all applicable 
helicopters, 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 by using the torque value 
information identified in this proposed AD or identified in ASB 210-21-
15, Rev A as applicable.
    Thereafter, for all applicable helicopters, this proposed AD would 
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, this proposed AD would prohibit installing certain part-
numbered steel alloy nuts on any Model 204B helicopters; and would 
prohibit installing certain part-numbered steel alloy barrel nuts on 
any Model 205A, 205A-1, 205B, and 210 helicopters.

Differences Between This SNPRM and the Service Information

    The service information specifies checking torque, whereas this 
proposed AD would require inspecting torque because that action must be 
accomplished by persons authorized under 14 CFR 43.3.
    When stabilizing the tail boom attachment hardware torque, the 
service information does not specify what to do if the torque on a tail 
boom attachment bolt is below the minimum allowable torque limit, 
whereas this proposed AD would require 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 proposed AD would affect 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 proposed 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 would 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 would be 
approximately $196 and the parts cost for the other bolts would be 
approximately $89 per bolt. The parts cost for four new nuts would be 
approximately $680. The parts cost to apply torque stripes would be a 
nominal amount. The estimated cost for these actions would be up to 
approximately

[[Page 38849]]

$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 
would 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) would be approximately $680. The parts cost 
for an upper LH bolt would be approximately $196 and the parts cost for 
the other bolts would be approximately $89 per bolt. The parts cost to 
apply torque stripes would be a nominal amount. The estimated cost for 
these actions would be up to approximately $1,866 per helicopter and 
$98,898 for the U.S. fleet.
    For the intital 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 would 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) would be approximately 
$680. The parts cost for an upper LH bolt would be approximately $196 
and the parts cost for the other bolts would be approximately $89 per 
bolt. The parts cost to apply torque stripes would be a nominal amount. 
The estimated cost for these actions would 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 would 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 would take up to 
approximately 5 work-hours. The parts cost for an upper LH bolt would 
be approximately $196 and the parts cost to apply a torque stripe would 
be a nominal amount. The estimated cost for these actions would 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 would 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 would take a minimal amount 
of additional time and the parts cost would be approximately $89.
    If required as a result of failing any torque inspection required 
by this proposed AD, visually inspecting a nut or a barrel nut, 
replacing a bolt, stabilizing the torque, and applying a torque stripe 
would take up to approximately 5.5 work-hours per failed hardware set. 
The parts cost for an upper LH bolt would be approximately $196 and the 
parts cost for the other bolts would be approximately $89 per bolt. The 
parts cost to apply a torque stripe would be a nominal amount. The 
estimated cost for these actions would be $664 (upper LH bolt) or $557 
(other bolts), per failed hardware set. If required, replacing a nut 
following that inspection would take a minimal amount of additional 
time and the parts cost for a nut would be approximately $89 per nut, 
and if required, replacing a barrel nut following that inspection would 
take a minimal amount of additional time and the parts cost for a 
barrel nut (including retainer) would be 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

    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 above, 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.


Sec.  39.13  [Amended]

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

Bell Textron Inc.: Docket No. FAA-2022-0600; Project Identifier AD-
2021-01160-R.

(a) Comments Due Date

    The FAA must receive comments on this airworthiness directive 
(AD) by June 24, 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.

[[Page 38850]]

(f) Compliance

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

(g) Allowable Torque Values (in-lbs)

----------------------------------------------------------------------------------------------------------------
                                                                    Model 205A/
           Tail boom attachment point               Model 204B        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 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,

[[Page 38851]]

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) For helicopters identified in paragraph (c) of this AD, 
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, as 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 204 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) 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) For helicopters identified in paragraph (c) of this AD, 
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) For helicopters identified in paragraph (c) of this AD, 
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

[[Page 38852]]

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 [email protected].
    (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: [email protected].

(l) Material Incorporated by Reference

    (1) The Director of the Federal Register approved the 
incorporation by reference (IBR) of the service information listed 
in this paragraph under 5 U.S.C. 552(a) and 1 CFR part 51.
    (2) You must use this service information 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 service information 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 
[email protected]; or website: bellflight.com/support/contact-support.
    (4) You may view this service information at the FAA, Office of 
Regional Counsel, Southwest Region, 10101 Hillwood Pkwy., Fort 
Worth, TX 76177. For information on the availability 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 [email protected].

    Issued on April 26, 2024.
James D. Foltz,
Deputy Director, Compliance & Airworthiness Division, Aircraft 
Certification Service.
[FR Doc. 2024-09572 Filed 5-1-24; 4:15 pm]
BILLING CODE 4910-13-P