51038 Federal Register / Vol. 86, No. 175 / Tuesday, September 14, 2021 / Proposed Rules 

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

§ 39.13 [Amended] 

■ 2. The FAA amends § 39.13 by: 

■ a. Removing Airworthiness Directive 

2021–06–06, Amendment 39–21473 (86 

FR 14366, March 16, 2021); and 

■ b. Adding the following new 

airworthiness directive: 

Bell Textron Canada Limited: Docket No. 

FAA–2021–0729; Project Identifier 

MCAI–2021–00364–R. 

(a) Comments Due Date 

The FAA must receive comments on this 

airworthiness directive (AD) action by 

October 29, 2021. 

(b) Affected ADs 

This AD replaces AD 2021–06–06, 

Amendment 39–21473 (86 FR 14366, March 

16, 2021) (AD 2021–06–06). 

(c) Applicability 

This AD applies to Bell Textron Canada 

Limited Model 505 helicopters, serial 

number (S/N) 65011 through 65347 

inclusive, certificated in any category. 

(d) Subject 

Joint Aircraft Service Component (JASC) 

Code: 6710, Main Rotor Control. 

(e) Unsafe Condition 

This AD was prompted by a report of a 

cracked pilot collective stick and grip 

assembly. The FAA is issuing this AD to 

detect a cracked pilot collective stick and 

grip assembly. The unsafe condition, if not 

addressed, could result in failure of the pilot 

collective stick and grip assembly 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) Before further flight after the effective 

date of this AD, revise the Limitations section 

of the existing Rotorcraft Flight Manual 

(RFM) for your helicopter by inserting Bell 

505 RFM Temporary Revision (TR) for Pilot 

Collective (ASB 505–21–20), BHT–505–FM– 

1, Temporary Revision (TR–6) or Bell 505 

RFM TR for Pilot Collective (ASB 505–21– 

20), BHT–505–FM–2, Temporary Revision 

(TR–1), each dated March 3, 2021, as 

applicable to your helicopter. Using a 

different document with information 

identical to the information for the ‘‘Flight 

Crew’’ and ‘‘Configuration,’’ as applicable to 

your helicopter, in the RFM TR specified in 

this paragraph for your helicopter is 

acceptable for compliance with the 

requirements of this paragraph. This action 

may be performed by the owner/operator 

(pilot) holding at least a private pilot 

certificate and must be entered into the 

aircraft records showing compliance with 

this AD in accordance with § 43.9(a)(1) 

through (4) and § 91.417(a)(2)(v). The record 

must be maintained as required by § 91.417, 

§ 121.380, or § 135.439. 

(2) Before further flight after the effective 

date of this AD, and thereafter at intervals not 

to exceed 25 hours time-in-service (TIS): 

(i) Remove the pilot collective stick and 

grip assembly from the jackshaft assembly 

and clean the areas specified in Figure 2 of 

Bell Alert Service Bulletin 505–21–20, 

Revision C, dated March 11, 2021 (ASB 505– 

21–20 Rev C) with a clean cloth C–516C or 

equivalent moistened with dry cleaning 

solvent C–304 or equivalent. 

(ii) Perform a fluorescent penetrant 

inspection (FPI) for a crack by following the 

Accomplishment Instructions, Part I, 

paragraph 5. (but not paragraphs 5.a. and b.) 

of ASB 505–21–20 Rev C. Perform this FPI 

in the areas specified in Figure 2 of ASB 505– 

21–20 Rev C. If there is a crack, before further 

flight, remove the pilot collective stick and 

grip assembly from service. 

(3) Within 12 months after the effective 

date of this AD, remove the pilot collective 

stick tube from service and install pilot 

collective stick tube part number (P/N) 

M207–20M301–043 by following the 

Accomplishment Instructions, Part II, 

paragraphs 3. through 4. of ASB 505–21–20 

Rev C except where this service information 

specifies discarding parts, you are required to 

remove those parts from service instead. 

Thereafter, remove from service pilot 

collective stick tube P/N M207–20M301–043 

before it accumulates 300 total hours TIS 

(4) Completing the actions required in 

paragraph (g)(3) of this AD constitutes a 

terminating action for the requirements in 

paragraphs (g)(1) and (2) of this AD. 

(5) As of the effective date of this AD, do 

not install any pilot collective stick and grip 

assembly on any helicopter unless the 

actions required by paragraphs (g)(2) and 

(g)(3) of this AD have been accomplished. 

(6) As of the effective date of this AD, relief 

under any Master Minimum Equipment List 

or Minimum Equipment List for the Audio 

Panel is prohibited when the aircraft is 

operated with a single pilot. 

(h) Credit for Previous Actions 

If you performed an FPI of the pilot 

collective stick and grip assembly before the 

effective date of this AD using Bell Alert 

Service Bulletin 505–21–20, dated February 

20, 2021, Bell Alert Service Bulletin 505–21– 

20, Revision A, dated February 26, 2021, or 

Bell Alert Service Bulletin 505–21–20, 

Revision B, dated March 3, 2021, you met the 

before further flight FPI requirement of 

paragraph (g)(2) of this AD. 

(i) Special Flight Permits 

A special flight permit to a maintenance 

facility may be granted provided that: 

(1) There are no passengers on-board, 

(2) The helicopter is flown from the copilot 

seat only, and 

(3) The GMA (intercom) is operative. 

(j) Alternative Methods of Compliance 

(AMOCs) 

(1) The Manager, International Validation 

Branch, FAA, has the authority to approve 

AMOCs for this AD, if requested using the 

procedures found in 14 CFR 39.19. In 

accordance with 14 CFR 39.19, send your 

request to your principal inspector or local 

Flight Standards District Office, as 

appropriate. If sending information directly 

to the manager of the International Validation 

Branch, send it to the attention of the person 

identified in paragraph (k)(1) of this AD. 

Information may be emailed to: 9-AVS-AIR730-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. 

(k) Related Information 

(1) For more information about this AD, 

contact Hal Jensen, Aerospace Engineer, 

Operational Safety Branch, Compliance & 

Airworthiness Division, FAA, 950 L’Enfant 

Plaza N SW, Washington, DC 20024; 

telephone (202) 267–9167; email hal.jensen@

faa.gov. 

(2) For service information identified in 

this AD, contact Bell Textron Canada 

Limited, 12,800 Rue de l’Avenir, Mirabel, 

Quebec J7J1R4; telephone 1–450–437–2862 

or 1–800–363–8023; fax 1–450–433–0272; 

email productsupport@bellflight.com; or at 

https://www.bellflight.com/support/contactsupport. You may view this referenced 

service information at the FAA, Office of the 

Regional Counsel, Southwest Region, 10101 

Hillwood Pkwy., Room 6N–321, Fort Worth, 

TX 76177. For information on the availability 

of this material at the FAA, call (817) 222– 

5110. 

(3) The subject of this AD is addressed in 

Transport Canada AD CF–2021–05R3, dated 

March 19, 2021. You may view the Transport 

Canada AD on the internet at https://

www.regulations.gov in Docket No. FAA– 

2021–0729. 

Issued on September 2, 2021. 

Gaetano A. Sciortino, 

Deputy Director for Strategic Initiatives, 

Compliance & Airworthiness Division, 

Aircraft Certification Service. 

[FR Doc. 2021–19608 Filed 9–13–21; 8:45 am] 

BILLING CODE 4910–13–P 

DEPARTMENT OF TRANSPORTATION 

Federal Aviation Administration 

14 CFR Part 39 

[Docket No. FAA–2021–0728; Project 

Identifier MCAI–2020–00656–R] 

RIN 2120–AA64 

Airworthiness Directives; Bell Textron 

Canada Limited 

AGENCY: Federal Aviation 

Administration (FAA), DOT. 

ACTION: Notice of proposed rulemaking 

(NPRM). 

SUMMARY: The FAA proposes to adopt a 

new airworthiness directive (AD) for 

certain Bell Textron Canada Limited 

Model 206, 206A, 206A–1, 206B, 206B– 

1, 206L, 206L–1, 206L–3, and 206L–4 

helicopters. This proposed AD was 


tkelley on DSK125TN23PROD with PROPOSALS
Federal Register / Vol. 86, No. 175 / Tuesday, September 14, 2021 / Proposed Rules 51039 

prompted by reports of cracked or 

missing nuts on the tail rotor drive shaft 

(TRDS) disc pack (Thomas) couplings. 

This proposed AD would require 

removing certain nuts from service, 

installing newly designed nuts, and 

applying a specific torque and a torque 

stripe to each newly installed nut. This 

proposed AD would then require, after 

the installation of each newly designed 

nut, inspecting the torque and, 

depending on the inspection results, 

either applying a torque stripe or 

performing further inspections and 

removing certain parts from service. 

Finally, this proposed AD would 

prohibit installing any affected nut on 

any TRDS Thomas coupling. 

The FAA is proposing this AD to 

address the unsafe condition on these 

products. 

DATES: The FAA must receive comments 

on this proposed AD by October 29, 

2021. 

ADDRESSES: You may send comments, 

using the procedures found in 14 CFR 

11.43 and 11.45, by any of the following 

methods: 

• Federal eRulemaking Portal: Go to 

https://www.regulations.gov. Follow the 

instructions for submitting comments. 

• Fax: (202) 493–2251. 

• Mail: U.S. Department of 

Transportation, Docket Operations, 

M–30, West Building Ground Floor, 

Room W12–140, 1200 New Jersey 

Avenue SE, Washington, DC 20590. 

• Hand Delivery: Deliver to Mail 

address between 9 a.m. and 5 p.m., 

Monday through Friday, except Federal 

holidays. 

For service information identified in 

this NPRM, contact Bell Textron Canada 

Limited, 12,800 Rue de l’Avenir, 

Mirabel, Quebec J7J 1R4, Canada; 

telephone 1–450–437–2862 or 1–800– 

363–8023; fax 1–450–433–0272; email 

productsupport@bellflight.com; or at 

https://www.bellflight.com/support/ 

contact-support. You may view this 

service information at the FAA, Office 

of the Regional Counsel, Southwest 

Region, 10101 Hillwood Pkwy., Room 

6N–321, Fort Worth, TX 76177. For 

information on the availability of this 

material at the FAA, call (817) 222– 

5110. 

Examining the AD Docket 

You may examine the AD docket at 

https://www.regulations.gov by 

searching for and locating Docket No. 

FAA–2021–0728; or in person at Docket 

Operations between 9 a.m. and 5 p.m., 

Monday through Friday, except Federal 

holidays. The AD docket contains this 

NPRM, the Transport Canada AD, any 

comments received, and other 

information. The street address for 

Docket Operations is listed above. 

FOR FURTHER INFORMATION CONTACT: Matt 

Fuller, AD Program Manager, General 

Aviation & Rotorcraft Unit, 

Airworthiness Products Section, 

Operational Safety Branch, FAA, 10101 

Hillwood Pkwy., Fort Worth, TX 76177; 

telephone (817) 222–5110; email 

matthew.fuller@faa.gov. 

SUPPLEMENTARY INFORMATION: 

Comments Invited 

The FAA invites you to send any 

written relevant data, views, or 

arguments about this proposal. Send 

your comments to an address listed 

under ADDRESSES. Include ‘‘Docket No. 

FAA–2021–0728; Project Identifier 

MCAI–2020–00656–R’’ at the beginning 

of your comments. The most helpful 

comments reference a specific portion of 

the proposal, explain the reason for any 

recommended change, and include 

supporting data. The FAA will consider 

all comments received by the closing 

date and may amend this proposal 

because of those comments. 

Except for Confidential Business 

Information (CBI) as described in the 

following paragraph, and other 

information as described in 14 CFR 

11.35, the FAA will post all comments 

received, without change, to https://

www.regulations.gov, including any 

personal information you provide. The 

agency will also post a report 

summarizing each substantive verbal 

contact received about this NPRM. 

Confidential Business Information 

CBI is commercial or financial 

information that is both customarily and 

actually treated as private by its owner. 

Under the Freedom of Information Act 

(FOIA) (5 U.S.C. 552), CBI is exempt 

from public disclosure. If your 

comments responsive to this NPRM 

contain commercial or financial 

information that is customarily treated 

as private, that you actually treat as 

private, and that is relevant or 

responsive to this NPRM, it is important 

that you clearly designate the submitted 

comments as CBI. Please mark each 

page of your submission containing CBI 

as ‘‘PROPIN.’’ The FAA will treat such 

marked submissions as confidential 

under the FOIA, and they will not be 

placed in the public docket of this 

NPRM. Submissions containing CBI 

should be sent to Matt Fuller, AD 

Program Manager, General Aviation & 

Rotorcraft Unit, Airworthiness Products 

Section, Operational Safety Branch, 

FAA, 10101 Hillwood Pkwy., Fort 

Worth, TX 76177; telephone (817) 222– 

5110; email matthew.fuller@faa.gov. 

Any commentary that the FAA receives 

which is not specifically designated as 

CBI will be placed in the public docket 

for this rulemaking. 

Background 

Transport Canada, which is the 

aviation authority for Canada, has 

issued Canadian AD CF–2019–34, dated 

September 25, 2019 (Transport Canada 

AD CF–2019–34), to correct an unsafe 

condition for Bell Helicopter Textron 

Canada Limited (now Bell Textron 

Canada Limited) Model 206, 206A, 

206A–1, 206B, 206B–1, 206L, 206L–1, 

206L–3, and 206L–4 helicopters, all 

serial numbers. Transport Canada AD 

CF–2019–34 advised of reports of 

cracked or missing nuts at the TRDS 

Thomas couplings, which could have 

been caused by improper torque or 

hydrogen embrittlement. This 

condition, if not addressed, could result 

in loss of the tail rotor and subsequent 

loss of control of the helicopter. 

After Transport Canada issued 

Transport Canada AD CF–2019–34, it 

was determined that helicopters 

modified in accordance with 

Supplemental Type Certificate (STC) 

SH2750NM or Transport Canada STC 

SH99–202, were not able to comply 

with AD CF–2019–34. Accordingly, 

Transport Canada issued AD CF–2020– 

15, dated May 13, 2020 (Transport 

Canada AD CF–2020–15) which 

supersedes Transport Canada AD CF– 

2019–34, and contains a new 

requirement for helicopters with STC 

SH2750NM or Transport Canada STC 

SH99–202 installed or models that have 

been modified per Bell Service 

Instruction BHT–206–SI–2052, Revision 

1, dated October 14, 2010 (BHT–206– 

SI–2052). Transport Canada advises for 

certain model helicopters, the newly 

designed nuts cannot be installed 

because STC SH2750NM and Transport 

Canada STC SH99–202 install a pulley 

at the Thomas coupling location causing 

insufficient clearance. Transport Canada 

further advises for certain model 

helicopters with STC SH2750NM or 

Transport Canada STC SH99–202 

installed, different part-numbered nuts 

may be installed which were not 

identified in the applicable service 

information and are now required to be 

replaced with a new part-numbered nut 

that is not vulnerable to the unsafe 

condition. Accordingly, Air Comm 

Corporation, the STC holder for STC 

SH2750NM, issued new service 

information to address these additional 

issues and provide newly developed 

instructions which apply to certain 

model helicopters with STC SH2750NM 

or Transport Canada STC SH99–202 

installed. 


tkelley on DSK125TN23PROD with PROPOSALS
51040 Federal Register / Vol. 86, No. 175 / Tuesday, September 14, 2021 / Proposed Rules 

Additionally, Transport Canada 

advises that BHT–206–SI–2052 which is 

optional, specifies procedures for Model 

206L–1 and 206L–3 helicopters to 

upgrade the airframe and systems and 

also includes installation of the Model 

206L–4 TRDS Thomas coupling. 

According to Transport Canada, models 

that have incorporated BHT–206–SI– 

2052, with STC SH2750NM or 

Transport Canada STC SH99–202 

installed, will have the Model 206L–4 

helicopter pulley configuration and are 

subject to the Air Comm Corporation 

service information. 

Accordingly, Transport Canada AD 

CF–2020–15 requires the replacement of 

the affected nuts with the newly 

designed nuts at each TRDS Thomas 

coupling. 

FAA’s Determination 

These helicopters have been approved 

by the aviation authority of Canada and 

are approved for operation in the United 

States. Pursuant to the FAA’s bilateral 

agreement with Canada, Transport 

Canada, its technical representative, has 

notified the FAA of the unsafe condition 

described in the Transport Canada AD. 

The FAA is proposing this AD after 

evaluating all known relevant 

information and determining that an 

unsafe condition is likely to exist or 

develop on other helicopters of the same 

type design. 

Related Service Information Under 1 

CFR Part 51 

The FAA reviewed Bell Alert Service 

Bulletin 206–19–136, dated August 27, 

2019, and Bell Alert Service Bulletin 

206L–19–181, Revision A, dated August 

29, 2019. This service information 

specifies procedures for replacing the 

affected nuts with the newly designed 

corrosion-resistant nuts. 

This service information is reasonably 

available because the interested parties 

have access to it through their normal 

course of business or by the means 

identified in the ADDRESSES section. 

Other Related Service Information 

The FAA reviewed Air Comm 

Corporation Service Bulletin SB 206EC– 

092619, Revision NC, dated September 

26, 2019, which also specifies 

procedures for replacing the affected 

nuts with the newly designed corrosionresistant nuts, but explains that affected 

helicopters equipped with Air Comm 

Corporation air conditioning systems 

installed under STC SH2750NM use the 

affected nut to attach a pulley onto the 

TRDS, which causes clearance issues for 

the nuts to be installed at the coupling. 

Therefore, this service bulletin specifies 

replacing the nut with a lower profile 

nut. 

The FAA also reviewed BHT–206–SI– 

2052. This service information specifies 

procedures to upgrade Model 206L–1 

and 206L–3 helicopters to allow 

operations at an increased internal gross 

weight. 

Proposed AD Requirements in This 

NPRM 

This proposed AD would require 

within 600 hours time-in-service (TIS) 

after the effective date of this AD, 

removing from service each affected nut, 

and installing a newly designed nut. 

This proposed AD would also require 

applying a specific torque and a torque 

stripe to each newly installed nut. This 

proposed AD would also require, within 

25 hours TIS after installation of each 

newly designed nut, inspecting the 

torque of each nut, and depending on 

the results of the inspection, this 

proposed AD would require further 

inspections and removing certain parts 

from service. Finally, this proposed AD 

would prohibit installing any affected 

nut on any on any TRDS Thomas 

coupling. 

Differences Between This Proposed AD 

and the Transport Canada AD 

The Transport Canada AD requires 

compliance within 600 hours air time or 

within the next 24-months, whichever 

occurs first, whereas this proposed AD 

would require compliance within 600 

hours TIS and an additional inspection 

at 25 hours TIS after installation of 

certain nuts. 

Costs of Compliance 

The FAA estimates that this proposed 

AD would affect 1439 helicopters of 

U.S. Registry. The FAA estimates that 

operators may incur the following costs 

in order to comply with this proposed 

AD. Labor costs are estimated at $85 per 

work-hour. 

Replacing each affected nut with the 

newly designed nut and applying torque 

and a torque stripe would take about 4 

work-hours, and parts would cost about 

$75 for an estimated cost of $415 per 

nut replacement and $597,185 per nut 

replacement for the U.S. fleet. 

Replacing each TRDS Thomas 

coupling would take about 4 workhours, and parts would cost about 

$4,000 for an estimated cost of $4,340 

per TRDS Thomas coupling 

replacement. 

If required, inspecting the torque of 

each newly installed nut, and inspecting 

each TRDS Thomas coupling, each bolt, 

nut and washer for elongated holes and 

fretting on the fasteners would take 

about 0.5 work-hours for an estimated 

cost of $43 per inspection. 

Authority for This Rulemaking 

Title 49 of the United States Code 

specifies the FAA’s authority to issue 

rules on aviation safety. Subtitle I, 

section 106, describes the authority of 

the FAA Administrator. Subtitle VII: 

Aviation Programs, describes in more 

detail the scope of the Agency’s 

authority. 

The FAA is issuing this rulemaking 

under the authority described in 

Subtitle VII, Part A, Subpart III, Section 

44701: General requirements. Under 

that section, Congress charges the FAA 

with promoting safe flight of civil 

aircraft in air commerce by prescribing 

regulations for practices, methods, and 

procedures the Administrator finds 

necessary for safety in air commerce. 

This regulation is within the scope of 

that authority because it addresses an 

unsafe condition that is likely to exist or 

develop on products identified in this 

rulemaking action. 

Regulatory Findings 

The FAA determined that this 

proposed AD would not have federalism 

implications under Executive Order 

13132. This proposed AD would not 

have a substantial direct effect on the 

States, on the relationship between the 

national Government and the States, or 

on the distribution of power and 

responsibilities among the various 

levels of government. 

For the reasons discussed, I certify 

this proposed regulation: 

(1) Is not a ‘‘significant regulatory 

action’’ under Executive Order 12866, 

(2) Would not affect intrastate 

aviation in Alaska, and 

(3) Would not have a significant 

economic impact, positive or negative, 

on a substantial number of small entities 

under the criteria of the Regulatory 

Flexibility Act. 

List of Subjects in 14 CFR Part 39 

Air transportation, Aircraft, Aviation 

safety, Incorporation by reference, 

Safety. 

The Proposed Amendment 

Accordingly, under the authority 

delegated to me by the Administrator, 

the FAA proposes to amend 14 CFR part 

39 as follows: 

PART 39—AIRWORTHINESS 

DIRECTIVES 

■ 1. The authority citation for part 39 

continues to read as follows: 

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


tkelley on DSK125TN23PROD with PROPOSALS
Federal Register / Vol. 86, No. 175 / Tuesday, September 14, 2021 / Proposed Rules 51041 

§ 39.13 [Amended] 

■ 2. The FAA amends § 39.13 by adding 

the following new airworthiness 

directive: 

Bell Textron Canada Limited: Docket No. 

FAA–2021–0728; Project Identifier 

MCAI–2020–00656–R. 

(a) Comments Due Date 

The FAA must receive comments on this 

airworthiness directive (AD) by October 29, 

2021. 

(b) Affected ADs 

None. 

(c) Applicability 

This AD applies to Bell Textron Canada 

Limited Model 206, 206A, 206A–1, 206B, 

206B–1, 206L, 206L–1, 206L–3, and 206L–4 

helicopters, certificated in any category, with 

nut part number (P/N) MS21042L4 or P/N 

MS21042L5 installed on the tail rotor drive 

shaft (TRDS) disc pack (Thomas) couplings. 

Note 1 to paragraph (c): Helicopters with 

an OH–58A designation are Model 206A–1 

helicopters. 

(d) Subject 

Joint Aircraft Service Component (JASC) 

Code: 6510, Tail Rotor Drive Shaft. 

(e) Unsafe Condition 

This AD was prompted by reports of 

cracked or missing nuts installed on the 

TRDS Thomas couplings. The FAA is issuing 

this AD to prevent failure or loss of a nut on 

the TRDS Thomas couplings. The unsafe 

condition, if not addressed, could result in 

loss of the tail rotor and subsequent loss of 

control of the helicopter. 

(f) Compliance 

Comply with this AD within the 

compliance times specified, unless already 

done. 

(g) Required Actions 

(1) Within 600 hours time-in-service (TIS) 

after the effective date of this AD: 

(i) For helicopters that have not been 

modified by installing Supplemental Type 

Certificate (STC) SH2750NM: 

(A) Remove each nut P/N MS21042L4 

installed on each TRDS Thomas coupling 

from service, and replace with nut P/N 

NAS9926–4L. The location of nut P/N 

NAS9926–4L is depicted in Detail A Figure 

1 of Bell Alert Service Bulletin (ASB) 206– 

19–136, dated August 27, 2019 (ASB 206–19– 

136) or Bell ASB 206L–19–181, Revision A, 

dated August 29, 2019 (ASB 206L–19–181), 

as applicable to your model helicopter. 

(B) Apply a torque of 5.65 Nm (50 in lb) 

to each nut installed as required by 

paragraph (g)(1)(i)(A) of this AD, and apply 

a torque stripe using torque seal lacquer (C– 

049) or equivalent lacquer, as shown in 

Figure 2 of ASB 206–19–136 or ASB 206L– 

19–181, as applicable to your model 

helicopter. 

Note 2 to paragraph (g)(1)(i)(B): Torque 

stripes are referred to as witness marks in 

ASB 206–19–136 and ASB 206L–19–181. 

(ii) For Bell Textron Canada Limited Model 

206, 206A, 206A–1, 206B, 206B–1, and 206L 

helicopters that have been modified by 

installing STC SH2750NM and Model 206L– 

1, and 206L–3 helicopters that have been 

modified by installing STC SH2750NM but 

have not been modified by accomplishing 

Bell Service Instruction BHT–206–SI–2052, 

Revision 1, dated October 14, 2010 (BHT– 

206–SI–2052): 

(A) Remove each nut P/N MS21042L4 

installed on each TRDS Thomas coupling 

from service, except for nuts P/N MS21042L4 

installed on the forward short TRDS Thomas 

coupling, and replace with nut P/N 

NAS9926–4L. The location of nut P/N 

NAS9926–4L is depicted in Detail A Figure 

1 of ASB 206–19–136 or ASB 206L–19–181 

as applicable to your model helicopter. 

(B) Remove each nut P/N MS21042L4 

installed on the forward short TRDS Thomas 

coupling from service and replace with nut 

P/N 90–132L4. 

(C) For each nut installed as required by 

paragraphs (g)(1)(ii)(A) and (B) of this AD, 

apply a torque of 5.65 Nm (50 in lb) to each 

nut and apply a torque stripe using torque 

seal lacquer (C–049) or equivalent lacquer, as 

shown in Figure 2 of ASB 206–19–136 or 

ASB 206L–19–181, as applicable to your 

model helicopter. 

(iii) For Bell Textron Canada Limited 

Model 206L–1, and 206L–3 helicopters that 

have been modified by installing STC 

SH2750NM and have been modified by 

accomplishing BHT–206–SI–2052: 

(A) Remove each nut P/N MS21042L4 

installed on each TRDS Thomas coupling 

from service, except for nuts P/N MS21042L4 

installed on the forward short TRDS Thomas 

coupling, and replace with nut P/N 

NAS9926–4L. The location of nut P/N 

NAS9926–4L is depicted in Detail A Figure 

1 of ASB 206L–19–181. 

(B) Remove each nut P/N MS21042L4 

installed on the forward short TRDS Thomas 

coupling from service and replace with nut 

P/N 90–132L4. 

(C) For each nut installed as required by 

paragraphs (g)(1)(iii)(A) and (B) of this AD, 

apply a torque of 5.65 Nm (50 in lb) to each 

nut, and apply a torque stripe using torque 

seal lacquer (C–049) or equivalent lacquer, as 

shown in Figure 2 of ASB 206L–19–181. 

(iv) For Bell Textron Canada Limited 

Model 206L–4 helicopters that have been 

modified by installing STC SH2750NM: 

(A) Remove each nut P/N MS21042L4 

installed on each TRDS Thomas coupling 

from service, except for nuts P/N MS21042L4 

installed on the forward short TRDS Thomas 

coupling, and replace with nut P/N 

NAS9926–4L. The location of nut P/N 

NAS9926–4L is depicted in Detail A Figure 

1 of ASB 206L–19–181. 

(B) Remove from service each nut P/N 

MS21042L5 installed on the forward short 

TRDS Thomas coupling and replace with nut 

P/N 90–132L5. 

(C) For each nut installed as required by 

paragraphs (g)(1)(iv)(A) and (B) of this AD, 

apply a torque of 5.65 Nm (50 in lb) to each 

nut, and apply a torque stripe using torque 

seal lacquer (C–049) or equivalent lacquer, as 

shown in Figure 2 of ASB 206L–19–181. 

(2) Within 25 hours TIS after installation 

of any nut P/N NAS9926–4L, P/N 90–132L4, 

or P/N 90–132L5, as required by paragraphs 

(g)(1)(i)(A), (ii)(A) and (B), (iii)(A) and (B), or 

(iv)(A) and (B) of this AD, apply a torque of 

5.65 Nm (50 in lb) to each nut. 

(i) If the nut does not move, apply a torque 

stripe using torque seal lacquer (C–049) or 

equivalent lacquer, as shown in Figure 2 of 

ASB 206–19–136 or ASB 206L–19–181, as 

applicable to your model helicopter. 

(ii) If any nut moves, inspect each TRDS 

Thomas coupling and each bolt, nut, and 

washer for elongated holes and fretting on 

the fasteners. If any TRDS Thomas coupling 

has an elongated hole, remove the TRDS 

Thomas coupling from service. If any bolt, 

nut, or washer has any fretting, remove the 

affected part from service. 

(3) As of the effective date of this AD, do 

not install nut P/N MS21042L4 or 

MS21042L5 on any TRDS Thomas coupling. 

(h) Alternative Methods of Compliance 

(AMOCs) 

(1) The Manager, International Validation 

Branch, FAA, has the authority to approve 

AMOCs for this AD, if requested using the 

procedures found in 14 CFR 39.19. In 

accordance with 14 CFR 39.19, send your 

request to your principal inspector or local 

Flight Standards District Office, as 

appropriate. If sending information directly 

to the manager of the International Validation 

Branch, send it to the attention of the person 

identified in paragraph (i)(1) of this AD. 

Information may be emailed to: 9-AVS-AIR730-AMOC@faa.gov. 

(2) Before using any approved AMOC, 

notify your appropriate principal inspector, 

or lacking a principal inspector, the manager 

of the local flight standards district office/ 

certificate holding district office. 

(i) Related Information 

(1) For more information about this AD, 

contact Matt Fuller, AD Program Manager, 

General Aviation & Rotorcraft Unit, 

Airworthiness Products Section, Operational 

Safety Branch, FAA, 10101 Hillwood Pkwy., 

Fort Worth, TX 76177; telephone (817) 222– 

5110; email matthew.fuller@faa.gov. 

(2) For service information identified in 

this AD, contact Bell Textron Canada 

Limited, 12,800 Rue de l’Avenir, Mirabel, 

Quebec J7J 1R4, Canada; telephone 1–450– 

437–2862 or 1–800–363–8023; fax 1–450– 

433–0272; email productsupport@

bellflight.com; or at https://

www.bellflight.com/support/contact-support. 

You may view this referenced service 

information at the FAA, Office of the 

Regional Counsel, Southwest Region, 10101 

Hillwood Pkwy., Room 6N–321, Fort Worth, 

TX 76177. For information on the availability 

of this material at the FAA, call (817) 222– 

5110. 

(3) The subject of this AD is addressed in 

Transport Canada AD CF–2020–15, dated 

May 13, 2020. You may view the Transport 

Canada AD on the internet at https://

www.regulations.gov in the AD Docket. 

Issued on September 2, 2021. 

Gaetano A. Sciortino, 

Deputy Director for Strategic Initiatives, 

Compliance & Airworthiness Division, 

Aircraft Certification Service. 

[FR Doc. 2021–19605 Filed 9–13–21; 8:45 am] 

BILLING CODE 4910–13–P 


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