80724 Federal Register / Vol. 89, No. 193 / Friday, October 4, 2024 / Rules and Regulations 

94 12 U.S.C. 5512(b)(1). 

95 44 U.S.C. 3501–3521. 

96 5 U.S.C. 801 et seq. 

out the purposes and objectives of 

Federal consumer financial laws.94

Insofar as the advisory opinion 

constitutes a general statement of 

policy, it provides background 

information about applicable law and 

articulates considerations relevant to the 

CFPB’s exercise of its authorities. It does 

not confer any rights of any kind. 

The CFPB has determined that this 

rule does not impose any new or revise 

any existing recordkeeping, reporting, or 

disclosure requirements on covered 

entities or members of the public that 

would be collections of information 

requiring approval by the Office of 

Management and Budget under the 

Paperwork Reduction Act.95

Pursuant to the Congressional Review 

Act,96 the CFPB will submit a report 

containing this interpretive rule and 

other required information to the United 

States Senate, the United States House 

of Representatives, and the Comptroller 

General of the United States prior to the 

rule’s published effective date. The 

Office of Information and Regulatory 

Affairs has designated this interpretive 

rule as a ‘‘major rule’’ as defined by 5 

U.S.C. 804(2). 

Rohit Chopra, 

Director, Consumer Financial Protection 

Bureau. 

[FR Doc. 2024–22962 Filed 10–3–24; 8:45 am] 

BILLING CODE 4810–AM–P 

DEPARTMENT OF TRANSPORTATION 

Federal Aviation Administration 

14 CFR Part 39 

[Docket No. FAA–2024–0768; Project 

Identifier AD–2022–00504–R; Amendment 

39–22825; AD 2024–16–19] 

RIN 2120–AA64 

Airworthiness Directives; Bell Textron 

Inc. Helicopters 

AGENCY: Federal Aviation 

Administration (FAA), DOT. 

ACTION: Final rule. 

SUMMARY: The FAA is adopting a new 

airworthiness directive (AD) for certain 

Bell Textron Inc. Model 212, 412, 

412CF, and 412EP helicopters. This AD 

was prompted by reports of cracked tail 

boom attachment barrel nuts (barrel 

nuts). This AD requires replacing all 

steel alloy barrel nuts with nickel alloy 

barrel nuts, replacing or inspecting 

other tail boom attachment point 

hardware, repetitively inspecting 

torque, and repetitively replacing tail 

boom attachment bolts (bolts). This AD 

also prohibits installing steel alloy 

barrel nuts. 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 certain publications 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–2024–0768; 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: 

• For Bell material identified in this 

AD, contact Bell Textron Inc., P.O. Box 

482, Fort Worth, TX 76101; phone: (450) 

437–2862 or 1–800–363–8023; fax: (450) 

433–0272; email: productsupport@

bellflight.com; or website: 

bellflight.com/support/contact-support. 

• You may view this material at the 

FAA, Office of the Regional Counsel, 

Southwest Region, 10101 Hillwood 

Parkway, Room 6N–321, Fort Worth, TX 

76177. For information on the 

availability of this material at the FAA, 

call (817) 222–5110. It is also available 

at regulations.gov under Docket No. 

FAA–2024–0768. 

FOR FURTHER INFORMATION CONTACT: 

Jacob Fitch, Aviation Safety Engineer, 

FAA, 1801 S Airport Road, Wichita, KS 

67209; phone: (817) 222–4130; email: 

jacob.fitch@faa.gov. 

SUPPLEMENTARY INFORMATION: 

Background 

The FAA issued a notice of proposed 

rulemaking (NPRM) to amend 14 CFR 

part 39 by adding an AD that would 

apply to certain serial-numbered Bell 

Textron Inc. (Bell) Model 212, 412, 

412CF, and 412EP helicopters. The 

NPRM published in the Federal 

Register on May 8, 2024 (89 FR 38841). 

The NPRM was prompted by reports of 

cracked barrel nuts on Model 412EP 

helicopters. According to Bell, the root 

cause for cracking can vary from 

corrosion damage, high time in service, 

or hydrogen embrittlement. Barrel nut 

cracking can also cause loss of torque on 

the associated bolt and subsequent bolt 

cracking. Due to design similarities, 

Model 212, 412, and 412CF helicopters 

are also affected. 

In the NPRM, the FAA proposed to 

require, for certain serial-numbered 

Model 212, 412CF, 412, and 412EP 

helicopters, replacing the upper lefthand (LH) steel alloy barrel nut and bolt 

with a new nickel alloy barrel nut, 

retainer, and bolt. For certain other 

serial-numbered Model 412 and 412EP 

helicopters, the FAA proposed to 

require removing the upper LH steel 

alloy barrel nut, inspecting the removed 

upper LH steel alloy barrel nut and 

replacing it with a nickel alloy barrel 

nut and retainer, and either inspecting 

or replacing the upper LH bolt. For 

those serial-numbered Model 212, 412, 

412CF, and 412EP helicopters, the FAA 

also proposed to require removing the 

upper right-hand (RH), lower LH, and 

lower RH steel alloy barrel nuts, 

inspecting those removed steel alloy 

barrel nuts and replacing them with 

new nickel alloy barrel nuts and 

retainers, and either inspecting or 

replacing the upper RH, lower LH, and 

lower RH bolts. Thereafter for those 

helicopters, as well as for one additional 

serial-numbered Model 412/412EP 

helicopter, 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. For all 

applicable helicopters, the FAA 

proposed to require repetitively 

inspecting the torque applied on each 

bolt within a longer-term compliance 

time interval and, depending on the 

results, replacing and inspecting certain 

tail boom attachment point hardware 

and repeating the torque inspections 

and stabilization, or applying torque 

stripes. Additionally, for all applicable 

helicopters, within a longer-term 

compliance time interval, the FAA 

proposed to require repetitively 

replacing the upper LH bolt and 

inspecting the other three bolts and, 

depending on the results, taking 

corrective action. Following 

accomplishment of those actions, 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 steel 

alloy barrel nuts on any helicopter. The 


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Federal Register / Vol. 89, No. 193 / Friday, October 4, 2024 / Rules and Regulations 80725 

FAA is issuing this AD to address the 

unsafe condition on these products. 

Discussion of Final Airworthiness 

Directive 

Comments 

The FAA received comments from 

Bell requesting changes to the 

Differences Between This Proposed AD 

and the Service Information section in 

the NPRM (the Differences Between 

This AD and the Referenced Material 

section in this final rule). The following 

presents the comments received on the 

NPRM and the FAA’s response to each 

comment. 

Request To Change the Torque 

Inspection Nomenclature 

In the NPRM, the FAA explained that 

while the service information specifies 

checking torque, the proposed AD 

would require inspecting the torque. 

Bell requested the FAA change the 

torque inspection to a torque check 

consistent with the terminology in its 

manuals and in the service information 

required by this AD. 

The FAA disagrees. The FAA’s 

regulatory definition of ‘‘maintenance’’ 

includes inspections but does not 

include checks. In certain ADs, the FAA 

uses the term ‘‘check’’ in limited 

situations when allowing a pilot to 

perform actions as an exception to the 

FAA’s standard maintenance 

regulations. For this AD, the specified 

torque verification requirement is a 

maintenance action that must be 

performed by persons authorized under 

14 CFR 43.3. Accordingly, this AD must 

use the term ‘‘inspection.’’ 

Comments Regarding Torque Below 

Minimum Allowable Limit 

In the NPRM, the FAA explained that 

for stabilizing the tail boom attachment 

hardware torque, the service 

information does not specify actions for 

if the torque on a bolt is below the 

minimum allowable torque, and 

therefore the proposed AD would 

require several actions. Bell stated that 

certain actions such as replacing the 

bolt, inspecting the associated barrel 

but, and repeating the torque inspection, 

are mandated by Bell Alert Service 

Bulletin (ASB) 412–21–187, Revision A, 

dated February 23, 2022, part II (torque 

stabilization) and part III (repetitive 

longer-term torque inspection) of ASB 

412–21–187, Revision A, February 23, 

2022. 

The torque stabilization procedures in 

part II of the Bell service bulletins 

specify corrective action if the torque 

has not stabilized after checking the 

torque up to three times maximum. 

However, the procedures do not specify 

any corrective action if the torque is 

below the minimum allowable torque 

limit as a result of any individual 

instance of a torque stabilization 

inspection. Similarly, the repetitive 

longer-term torque inspection 

procedures in part III of the Bell service 

bulletins specify additional actions if 

the torque is below the minimum 

allowable torque limit as a result of an 

inspection. However, the FAA 

determined that those part III 

procedures are somewhat vague and 

may be interpreted in more than one 

way. Thus, this AD contains specific 

actions for addressing torque below the 

minimum limits. The FAA has clarified 

this explanation in the Differences 

Between This AD and the Referenced 

Material section of this final rule. 

Comment Regarding the 5,000 Hours 

Time-in-Service (TIS) or 5 Year 

Required Actions 

In the NPRM, the FAA explained the 

proposed AD would require replacing 

the upper LH bolt and visually 

inspecting the upper RH and lower bolts 

within 5,000 hours TIS or 5 years, while 

the service information did not contain 

those actions. Bell stated that its service 

bulletins specify that the maintenance 

manual will be revised to include those 

actions. Bell also cited the 5,000 hour/ 

5-year inspection in the Bell Model 412/ 

412EP Maintenance Manual, Issue 001, 

dated May 31, 2023. 

The FAA has revised the Differences 

Between This AD and the Referenced 

Material in this final rule to explain that 

the referenced material specifies that the 

5,000 hours TIS or 5 year threshold 

actions will be incorporated into the 

maintenance manual. 

Additional Changes Made to This Final 

Rule 

Since the NPRM published, the FAA 

determined that paragraph (c) of the 

proposed AD incorrectly included some 

serial-numbered helicopters that are not 

eligible for an FAA airworthiness 

certificate. Therefore, the FAA has 

revised the applicability of this AD to 

remove those helicopters. The FAA has 

also updated the model for serial 

number 37052 in paragraph (c)(4) of this 

AD to Model 412EP, since it is currently 

registered as such. 

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 and other changes described 

previously, this AD is adopted as 

proposed in the NPRM. None of the 

changes will increase the economic 

burden on any operator. 

Material Incorporated by Reference 

Under 1 CFR Part 51 

The FAA reviewed the following Bell 

ASBs, each Revision A, and each dated 

February 23, 2022. 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 inspecting the torque. 

• ASB 212–21–166 for Model 212 

helicopters, 

• ASB 412–21–187 for Model 412/ 

412EP helicopters, and 

• ASB 412CF–21–72 for Model 412CF 

helicopters. 

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. 

Differences Between This AD and the 

Referenced Material 

The referenced material specifies 

checking torque, whereas this AD 

requires 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 

referenced 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 

a torque stripe. 

This AD requires replacing each 

upper LH bolt with a new (zero total 

hours TIS) bolt and visually inspecting 

the upper RH, lower LH, and lower RH 

bolts within a 5,000 hours TIS or 5 year 

threshold, whereas the referenced 

material states that these actions will be 

incorporated into the maintenance 

manual. 

Costs of Compliance 

The FAA estimates that this AD 

affects 105 helicopters of U.S. registry. 

Labor rates are estimated at $85 per 

work-hour. Based on these numbers, the 

FAA estimates the following costs to 

comply with this AD. 

For the initial requirements for certain 

helicopters, replacing the four steel 

alloy barrel nuts with new nickel alloy 

barrel nuts, inspecting or replacing up 

to four bolts, inspecting and stabilizing 


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the torque, and applying torque stripes 

will take up to approximately 8.5 workhours for an estimated labor cost of up 

to $723. The parts cost for the four new 

nickel alloy barrel nuts (including 

retainers) is approximately $680. The 

parts cost for an upper LH bolt is 

approximately $196 and the parts cost 

for the other bolts is approximately $89 

per bolt. The parts cost to apply torque 

stripes is a nominal amount. The 

estimated cost for these actions is up to 

approximately $1,866 per helicopter. 

For all applicable helicopters, 

inspecting the torque applied on each 

bolt will take approximately 1 workhour for an estimated cost of $85 per 

helicopter and $8,925 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 workhours. The parts cost for an upper LH 

bolt is approximately $196 and the parts 

cost to apply a torque stripe is a 

nominal amount. The estimated cost for 

these actions is up to approximately 

$621 per helicopter and $65,205 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 bolt and 

$31,290 for the U.S. fleet, per inspection 

cycle. If required, replacing a bolt 

following that inspection will take a 

minimal amount of additional time and 

a parts cost of approximately $89. 

If required as a result of failing a 

torque inspection, visually inspecting a 

barrel nut, replacing a bolt, stabilizing 

the torque, and applying a torque stripe 

will take up to approximately 5.5 workhours per failed hardware set. The parts 

cost for an upper LH bolt is 

approximately $196 and the parts cost 

for the other bolts is approximately $89 

per bolt. The parts cost to apply a torque 

stripe is a nominal amount. The 

estimated cost for these actions is $664 

(upper LH bolt) or $557 (other bolts), 

per failed hardware set. If required, 

replacing a barrel nut following that 

inspection will take a minimal amount 

of additional time with a parts cost for 

a barrel nut (including retainer) of 

approximately $173. 

If required as a result of failing a 

torque stabilization, replacing a barrel 

nut, visually inspecting a bolt, 

stabilizing the torque, and applying a 

torque stripe will take up to 

approximately 5.5 work-hours and the 

parts cost for a barrel nut (including 

retainer) is approximately $73. The 

estimated cost for these actions is $541. 

If required, replacing the bolt following 

that inspection will take a minimal 

amount of additional time with a parts 

cost for an upper LH bolt of 

approximately $196 and a parts cost for 

the other bolts of approximately $89 per 

bolt. 

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 

■ 1. The authority citation for part 39 

continues to read as follows: 

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

§ 39.13 [Amended] 

■ 2. The FAA amends § 39.13 by adding 

the following new airworthiness 

directive: 

2024–16–19 Bell Textron Inc.: Amendment 

39–22825; Docket No. FAA–2024–0768; 

Project Identifier AD–2022–00504–R. 

(a) Effective Date 

This airworthiness directive (AD) is 

effective November 8, 2024. 

(b) Affected ADs 

None. 

(c) Applicability 

This AD applies to the Bell Textron Inc. 

helicopters, certificated in any category, that 

are identified in paragraphs (c)(1) through (5) 

of this AD. 

(1) Model 212 helicopters, serial numbers 

(S/N) 30501 through 30603 inclusive, 30611 

through 30753 inclusive, 30755 through 

30889 inclusive, 30891 through 30999 

inclusive, 31101 through 31162 inclusive, 

31164 through 31311 inclusive, 32101 

through 32142 inclusive, and 35001 through 

35103 inclusive; 

(2) Model 412CF helicopters, S/N 46400 

through 46499 inclusive; 

(3) Model 412 and 412EP helicopters, S/N 

33001 to 33078 inclusive, 33080 through 

33129 inclusive, 33131 through 33138 

inclusive, 33150 through 33213 inclusive, 

36001 through 36687 inclusive, 36689 

through 36999 inclusive, 37002 through 

37018 inclusive, 37021 through 37051 

inclusive, 38001, and 39101 through 39103 

inclusive; 

(4) Model 412EP helicopter, S/N 37052; 

and 

(5) Model 412 and 412EP helicopters, S/N 

36688, 37019, 37020, 37053 through 37999 

inclusive, 38002 through 38999 inclusive, 

and 39104 through 39999 inclusive. 

(d) Subject 

Joint Aircraft System Component (JASC) 

Code: 5302, Rotorcraft Tail Boom. 

(e) Unsafe Condition 

This AD was prompted by reports of 

cracked tail boom attachment barrel nuts 

(barrel nuts). The FAA is issuing this AD to 

address fatigue cracking of barrel nuts, 

damage to the tail boom attachment bolts 

(bolts), and certain bolts remaining in service 

beyond fatigue limits. The unsafe condition, 

if not addressed, could result in increased 

fatigue loading and subsequent failure of the 

bolts, which could lead to 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) 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 (g)(1)(i) 


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through (iv) of this AD, as applicable. For 

purposes of this AD, the word ‘‘new’’ is 

defined as having zero total hours TIS. 

(i) For all helicopters identified in 

paragraphs (c)(1) and (2) of this AD; and for 

helicopters identified in paragraph (c)(3) of 

this AD that have accumulated 5,000 or more 

total hours TIS or 5 or more years since new, 

or if the total hours TIS or age of the 

helicopter is unknown, remove the upper 

left-hand (LH) steel alloy barrel nut part 

number (P/N) NAS577B9A and upper LH 

bolt from service and replace them with a 

new nickel alloy barrel nut P/N NAS577C9A, 

new retainer P/N NAS578C9A, and a new 

bolt in accordance with the Accomplishment 

Instructions, part I, paragraphs 4 through 7, 

of Bell Alert Service Bulletin 212–21–166, 

Revision A, dated February 23, 2022 (ASB 

212–21–166 Rev A), Bell Alert Service 

Bulletin 412CF–21–72, Revision A, dated 

February 23, 2022 (ASB 412CF–21–72 Rev 

A), or Bell Alert Service Bulletin 412–21– 

187, Revision A, dated February 23, 2022 

(ASB 412–21–187 Rev A), as applicable to 

your helicopter model, except you are not 

required to discard parts. 

(ii) For helicopters identified in paragraph 

(c)(3) of this AD that have accumulated less 

than 5,000 total hours TIS and less than 5 

years since new, remove the upper LH steel 

alloy barrel nut P/N NAS577B9A, the upper 

LH bolt, countersunk washer, and plain 

washers, and visually inspect the removed 

upper LH steel alloy barrel nut for cracking. 

If there is any cracking in the upper LH steel 

alloy barrel nut, before further flight, remove 

the upper LH bolt from service. If the upper 

LH bolt was not removed from service as a 

result of the upper LH steel alloy barrel nut 

inspection, visually inspect the upper LH 

bolt for any corrosion, damaged threads, 

wear, and fatigue cracking. If the upper LH 

bolt has any corrosion, a damaged thread, 

wear, or fatigue cracking, before further 

flight, remove the upper LH bolt from 

service. Regardless of the result of the upper 

LH steel alloy barrel nut inspection, remove 

the upper LH steel alloy barrel nut from 

service and replace it with a new nickel alloy 

barrel nut P/N NAS577C9A and new retainer 

P/N NAS578C9A. Install a new upper LH 

bolt or reinstall the existing upper LH bolt, 

as applicable, by following the 

Accomplishment Instructions, part I, 

paragraphs 6 and 7, of ASB 412–21–187 Rev 

A. 

(iii) For helicopters identified in 

paragraphs (c)(1) through (3) of this AD, 

remove the upper right-hand (RH) steel alloy 

barrel nut P/N NAS577B8A, the upper RH 

bolt, countersunk washer, and plain washers, 

and visually inspect the removed upper RH 

steel alloy barrel nut for cracking. If there is 

any cracking in the upper RH steel alloy 

barrel nut, before further flight, remove the 

upper RH bolt from service. If the upper RH 

bolt was not removed from service as a result 

of the upper RH steel alloy barrel nut 

inspection, visually inspect the upper RH 

bolt for any corrosion, damaged threads, 

wear, and fatigue cracking. If the upper RH 

bolt has any corrosion, a damaged thread, 

wear, or fatigue cracking, before further 

flight, remove the upper RH bolt from 

service. Regardless of the result of the upper 

RH steel alloy barrel nut inspection, remove 

the upper RH steel alloy barrel nut from 

service and replace it 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, 

as applicable, by following the 

Accomplishment Instructions, part I, 

paragraphs 11 and 12, of ASB 212–21–166 

Rev A, ASB 412–21–187 Rev A, or ASB 

412CF–21–72 Rev A, as applicable to your 

helicopter model. 

(iv) For helicopters identified in 

paragraphs (c)(1) through (3) of this AD, 

remove one of the lower steel alloy barrel 

nuts P/N NAS577B6A, its lower bolt, 

countersunk washer, and plain washers, and 

visually inspect the removed lower steel 

alloy barrel nut for cracking. If there is any 

cracking in the lower steel alloy barrel nut, 

before further flight, remove the lower bolt 

from service. If the lower bolt was not 

removed from service as a result of the lower 

steel alloy barrel nut inspection, visually 

inspect the lower bolt for any corrosion, 

damaged threads, wear, and fatigue cracking. 

If the lower bolt has any corrosion, a 

damaged thread, wear, or fatigue cracking, 

before further flight, remove the lower bolt 

from service. Regardless of the result of the 

lower steel alloy barrel nut inspection, 

remove the lower steel alloy barrel nut from 

service and replace it 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, as 

applicable, by following the Accomplishment 

Instructions, part I, paragraphs 16 and 17, of 

ASB 212–21–166 Rev A, ASB 412–21–187 

Rev A, or ASB 412CF–21–72 Rev A, as 

applicable to your helicopter model. Repeat 

the actions required by this paragraph for the 

other lower tail boom attachment point. 

(2) For helicopters identified in paragraphs 

(c)(1) through (3) of this AD, after 

accumulating 1 hour TIS, but not to exceed 

5 hours TIS after accomplishing the actions 

required by paragraph (g)(1) of this AD, using 

the torque value information in the 

Accomplishment Instructions, part II, 

paragraph 1, of ASB 212–21–166 Rev A, ASB 

412–21–187 Rev A, or ASB 412CF–21–72 Rev 

A, as applicable to your helicopter model, 

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 (g)(2)(i) and (ii) of this AD. 

Note 1 to the introductory text of 

paragraph (g)(2): This note applies to the 

introductory text of paragraph (g)(2), the 

introductory text of paragraph (g)(2)(i), 

paragraph (g)(2)(i)(B), and paragraph (g)(2)(ii) 

of this AD. The Accomplishment 

Instructions, part II, paragraph 1, of ASB 

212–21–166 Rev A, ASB 412–21–187 Rev A, 

and ASB 412CF–21–72 Rev A each refer to 

part I for allowable torque limits; part I of 

ASB 212–21–166 Rev A, ASB 412–21–187 

Rev A, and ASB 412CF–21–72 Rev A specify 

the different torque limits for the different 

bolts. 

(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 (g)(2)(i)(A) and (B) of 

this AD. 

(A) Remove the hardware set of one failed 

tail boom attachment point (barrel nut, 

retainer, bolt, countersunk washer, and plain 

washers). 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) Install a new bolt or reinstall the 

existing bolt, as applicable, and a new nickel 

alloy barrel nut P/N NAS577C9A, 

NAS577C8A, or NAS577C6A, and new 

retainer P/N NAS578C9A, NAS578C8A, or 

NAS578C6A, 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 by following the 

Accomplishment Instructions, part I, 

paragraphs 6 and 7, paragraphs 11 and 12, or 

paragraphs 16 and 17, of ASB 212–21–166 

Rev A, ASB 412–21–187 Rev A, or ASB 

412CF–21–72 Rev A, as applicable to your 

helicopter model and with the paragraphs as 

applicable to that bolt. Repeat the actions 

required by paragraphs (g)(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 

(g)(2) of this AD just for each newly installed 

or reinstalled bolt until the torque for all four 

tail boom attachment points stabilizes. 

(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 the helicopter identified in 

paragraph (c)(4) of this AD, within 5 hours 

TIS after the effective date of this AD, inspect 

the torque applied on each bolt in accordance 

with the Accomplishment Instructions, part 

II, paragraphs 1 and 2, of ASB 412–21–187 

Rev A. 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 (g)(2)(i) and (ii) of this AD. 

Note 2 to paragraph (g)(3): The 

Accomplishment Instructions, part II, 

paragraph 1, of ASB 412–21–187 Rev A refers 

to part I for allowable torque limits; part I of 

ASB 412–21–187 Rev A specifies the 

different torque limits for the different bolts. 

(4) For helicopters identified in paragraphs 

(c)(1) through (4) 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 (g)(2)(ii) of 

this AD, and thereafter within intervals not 

to exceed 600 hours TIS or 12 months, 

whichever occurs first; and for helicopters 

identified in paragraph (c)(5) of this AD, 

within 600 hours TIS or 12 months after the 

effective date of this AD, whichever occurs 

first, and thereafter within intervals not to 

exceed 600 hours TIS or 12 months, 


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80728 Federal Register / Vol. 89, No. 193 / Friday, October 4, 2024 / Rules and Regulations 

whichever occurs first, using the torque value 

information in the Accomplishment 

Instructions, part II, paragraph 1, of ASB 

212–21–166 Rev A, ASB 412–21–187 Rev A, 

or ASB 412CF–21–72 Rev A, as applicable to 

your helicopter model, inspect the torque 

applied on each bolt. If the torque on any bolt 

is below the minimum allowable torque 

limit, accomplish the actions required by 

paragraphs (g)(4)(i) and (ii) of this AD. 

(i) Before further flight, remove the 

hardware set of one failed tail boom 

attachment point (barrel nut, retainer, bolt, 

countersunk washer, and plain washers). 

Visually inspect the removed barrel nut for 

cracking, corrosion, and loss of tare torque. 

If the barrel nut has any cracking, corrosion, 

or has lost any 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 NAS577C9A, 

NAS577C8A, or NAS577C6A, and new 

retainer P/N NAS578C9A, NAS578C8A, or 

NAS578C6A, 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 by following the Accomplishment 

Instructions, part I, paragraphs 6 and 7, 

paragraphs 11 and 12, or paragraphs 16 and 

17, of ASB 212–21–166 Rev A, ASB 412–21– 

187 Rev A, or ASB 412CF–21–72 Rev A, as 

applicable to your helicopter model and with 

the paragraphs as applicable to that bolt. 

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 (g)(4)(i) of this 

AD, using the torque value information in the 

Accomplishment Instructions, part II, 

paragraph 1, of ASB 212–21–166 Rev A, ASB 

412–21–187 Rev A, or ASB 412CF–21–72 Rev 

A, as applicable to your helicopter model, 

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 (g)(2)(i) and (ii) of 

this AD. 

Note 3 to paragraph (g)(4): The 

Accomplishment Instructions, part II, 

paragraph 1, of ASB 212–21–166 Rev A, ASB 

412–21–187 Rev A, and ASB 412CF–21–72 

Rev A, each refer to part I for allowable 

torque limits; part I of ASB 212–21–166 Rev 

A, ASB 412–21–187 Rev A, and ASB 412CF– 

21–72 Rev A, specify the different torque 

limits for the different bolts. 

(5) Within the compliance times specified 

in Table 1 to the introductory text of 

paragraph (g)(5) of this AD, accomplish the 

actions required by paragraphs (g)(5)(i) 

through (iv) of this AD. 

Table 1 to the Introductory Text of 

Paragraph (g)(5) 

(i) Remove the upper LH bolt from service 

and replace it with a new upper LH bolt by 

following the Accomplishment Instructions, 

part I, paragraphs 6 and 7, of ASB 212–21– 

166 Rev A, ASB 412–21–187 Rev A, or ASB 

412CF–21–72 Rev A, as applicable to your 

helicopter model. Then accomplish the 

actions required by paragraph (g)(5)(v) of this 

AD. 

Note 4 to paragraph (g)(5)(i): This note 

applies to paragraphs (g)(5)(i) through (v) of 

this AD. The Accomplishment Instructions, 

part II, paragraph 1, of ASB 212–21–166 Rev 

A, ASB 412–21–187 Rev A, and ASB 412CF– 

21–72 Rev A, each refer to part I for 

allowable torque limits; part I of ASB 212– 

21–166 Rev A, ASB 412–21–187 Rev A, and 

ASB 412CF–21–72 Rev A, specify the 

different torque limits for the different bolts. 

(ii) With the upper RH bolt removed, 

visually inspect the upper RH bolt for any 

corrosion, damaged threads, wear, and 

fatigue cracking. If the upper RH bolt has any 

corrosion, a damaged thread, wear, or fatigue 

cracking, before further flight, remove the 

upper RH bolt from service. Install a new 


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Helicopter Groups Compliance Times 

For helicopters identified in Within 5,000 hours TIS or 5 years after 

paragraphs (c)(l) and (2) of this accomplishing the actions required by paragraph 

AD, and helicopters identified in (g)(l) of this AD, whichever occurs first, and 

paragraph (c)(3) of this AD that thereafter, within intervals not to exceed 5,000 

accomplished paragraph (g)( 1 )(i) hours TIS or 5 years, whichever occurs first. 

of this AD. 

For helicopters identified in Before the helicopter accumulates 5,000 total 

paragraph (c)(3) of this AD that hours TIS or 5 years since new, whichever occurs 

accomplished paragraph (g)( 1 )(ii) first, and thereafter, within intervals not to exceed 

of this AD. 5,000 hours TIS or 5 years, whichever occurs 

first. 

For helicopters identified in Before the helicopter accumulates 5,000 total 

paragraphs (c)(4) and (5) of this hours TIS or 5 years since new, whichever occurs 

AD. first, or if the total hours TIS or age of the 

helicopter is unknown, before further flight, and 

thereafter, within intervals not to exceed 5,000 

hours TIS or 5 years, whichever occurs first. 
Federal Register / Vol. 89, No. 193 / Friday, October 4, 2024 / Rules and Regulations 80729 

upper RH bolt or reinstall the existing upper 

RH bolt, as applicable, by following the 

Accomplishment Instructions, paragraphs 11 

and 12 of ASB 212–21–166 Rev A, ASB 412– 

21–187 Rev A, or ASB 412CF–21–72 Rev A, 

as applicable to your helicopter model. Then 

accomplish the actions required by paragraph 

(g)(5)(v) of this AD. 

(iii) With the lower LH bolt removed, 

visually inspect the lower LH bolt for any 

corrosion, damaged threads, wear, and 

fatigue cracking. If the lower LH bolt has any 

corrosion, a damaged thread, wear, or fatigue 

cracking, before further flight, remove the 

lower LH bolt from service. Install a new 

lower LH bolt or reinstall the existing lower 

LH bolt, as applicable, by following the 

Accomplishment Instructions, paragraphs 16 

and 17 of ASB 212–21–166 Rev A, ASB 412– 

21–187 Rev A, or ASB 412CF–21–72 Rev A, 

as applicable to your helicopter model. Then 

accomplish the actions required by paragraph 

(g)(5)(v) of this AD. 

(iv) With the lower RH bolt removed, 

visually inspect the lower RH bolt for any 

corrosion, damaged threads, wear, and 

fatigue cracking. If the lower RH bolt has any 

corrosion, a damaged thread, wear, or fatigue 

cracking, before further flight, remove the 

lower RH bolt from service. Install a new 

lower RH bolt or reinstall the existing lower 

RH bolt, as applicable, by following the 

Accomplishment Instructions, paragraphs 16 

and 17 of ASB 212–21–166 Rev A, ASB 412– 

21–187 Rev A, or ASB 412CF–21–72 Rev A, 

as applicable to your helicopter model. Then 

accomplish the actions required by paragraph 

(g)(5)(v) of this AD. 

(v) After accumulating 1 hour TIS, but not 

to exceed 5 hours TIS after accomplishing the 

actions required by paragraph (g)(5)(i), (ii), 

(iii), or (iv) of this AD, using the torque value 

information in the Accomplishment 

Instructions, part II, paragraph 1, of ASB 

212–21–166 Rev A, ASB 412–21–187 Rev A, 

or ASB 412CF–21–72 Rev A, as applicable to 

your helicopter model, 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 (g)(2)(i) and (ii) of this AD. 

(6) For helicopters identified in paragraph 

(c) of this AD, as of the effective date of this 

AD, do not install a steel alloy barrel nut P/ 

N NAS577B9A, P/N NAS577B8A, or P/N 

NAS577B6A on any helicopter. 

(h) 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. 

(i) 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 Central Certification 

Branch, send it to the attention of the person 

identified in paragraph (j) of this AD. 

Information may be emailed to 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. 

(j) Additional Information 

For more information about this AD, 

contact Jacob Fitch, Aviation Safety Engineer, 

FAA, 1801 S Airport Road, Wichita, KS 

67209; phone: (817) 222–4130; email: 

jacob.fitch@faa.gov. 

(k) 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 212–21–166, 

Revision A, dated February 23, 2022. 

(ii) Bell Alert Service Bulletin 412–21–187, 

Revision A, dated February 23, 2022. 

(iii) Bell Alert Service Bulletin 412CF–21– 

72, Revision A, dated February 23, 2022. 

(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 

1–800–363–8023; fax: (450) 433–0272; email: 

productsupport@bellflight.com; or website: 

bellflight.com/support/contact-support. 

(4) You may view this material at the FAA, 

Office of the Regional Counsel, Southwest 

Region, 10101 Hillwood Parkway, Room 6N– 

321, 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 fr.inspection@nara.gov. 

Issued on September 27, 2024. 

Victor Wicklund, 

Deputy Director, Compliance & Airworthiness 

Division, Aircraft Certification Service. 

[FR Doc. 2024–22929 Filed 10–3–24; 8:45 am] 

BILLING CODE 4910–13–P 

DEPARTMENT OF TRANSPORTATION 

Federal Aviation Administration 

14 CFR Part 39 

[Docket No. FAA–2024–2324; Project 

Identifier AD–2024–00514–T; Amendment 

39–22861; AD 2024–20–02] 

RIN 2120–AA64 

Airworthiness Directives; The Boeing 

Company Airplanes 

AGENCY: Federal Aviation 

Administration (FAA), DOT. 

ACTION: Final rule; request for 

comments. 

SUMMARY: The FAA is adopting a new 

airworthiness directive (AD) for all The 

Boeing Company Model 717–200 

airplanes and Model DC–9–10, DC–9– 

20, DC–9–30, DC–9–40, and DC–9–50 

series airplanes. This AD was prompted 

by a report of cracked and severed 

structure found in the aft fuselage cant 

bulkhead at a certain station (STA) and 

the vertical stabilizer rear spar 

installation. This AD requires a onetime inspection of the aft fuselage cant 

bulkhead at certain STAs and vertical 

stabilizer rear spar structure, and 

corrective actions and an inspection 

report if necessary. This AD also 

requires an inspection of that same 

structure if certain conditions occur 

during any phase of flight. The FAA is 

issuing this AD to address the unsafe 

condition on these products. 

DATES: This AD is effective October 21, 

2024. 

The Director of the Federal Register 

approved the incorporation by reference 

of certain publications listed in this AD 

as of October 21, 2024. 

The FAA must receive comments on 

this AD by November 18, 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–2024– 

2324; 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 street address for 

Docket Operations is listed above. 

Material Incorporated by Reference: 

• For Boeing material identified in 

this AD, contact Boeing Commercial 

Airplanes, Attention: Contractual & Data 

Services (C&DS), 2600 Westminster 

Blvd., MC 110–SK57, Seal Beach, CA 

90740–5600; telephone 562–797–1717; 

website myboeingfleet.com. 

• You may view this material at the 

FAA, Airworthiness Products Section, 


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