Airworthiness Directives; MD Helicopters, LLC Helicopters

Federal RegisterSep 15, 2026

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DEPARTMENT OF TRANSPORTATION

Federal Aviation Administration

14 CFR Part 39

[Docket No. FAA-2025-3987; Project Identifier AD-2025-00017-R; Amendment 39-23466; AD 2026-19-01]

RIN 2120-AA64

Airworthiness Directives; MD Helicopters, LLC Helicopters

AGENCY:

Federal Aviation Administration (FAA), DOT.

ACTION:

Final rule.

SUMMARY:

The FAA is superseding Airworthiness Directive (AD) 2024-23-

06, which applied to certain MD Helicopters, LLC Model 369, 369A, 369D, 369E, 369F, 369FF, 369H, 369HE, 369HM, 369HS, 500N, and 600N helicopters. AD 2024-23-06 required repetitively inspecting the torque tube assembly and roller bearings, and depending on the results, replacing parts or accomplishing additional inspections. Since the FAA issued AD 2024-23-06, the FAA has determined that additional torque tube assemblies are affected by this unsafe condition. This AD continues to require the actions of AD 2024-23-06 and expands the applicability. The FAA is issuing this AD to address the unsafe condition on these products.

DATES:

This AD is effective October 20, 2026.

ADDRESSES:

AD Docket:

You may examine the AD docket at

regulations.gov

under Docket No. FAA-2025-3987; 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.

FOR FURTHER INFORMATION CONTACT:

Eduardo Orozco-Duran, Aviation Safety Engineer, FAA, 3960 Paramount Boulevard, Lakewood, CA 90712; phone: (562) 627-5264; email:

eduardo.orozco-duran@faa.gov

SUPPLEMENTARY INFORMATION:

Background

The FAA issued a notice of proposed rulemaking (NPRM) to amend 14 CFR part 39 to supersede AD 2024-23-06, Amendment 39-22885 (89 FR 91248, November 19, 2024) (AD 2024-23-06). AD 2024-23-06 applied to certain MD Helicopters, LLC Model 369, 369A, 369D, 369E, 369F, 369FF, 369H, 369HE, 369HM, 369HS, 500N, and 600N helicopters. AD 2024-23-06 was prompted by a report of a seized and damaged roller bearing assembly in the torque tube assembly of an MD Helicopters, LLC Model 369E helicopter. AD 2024-23-06 required repetitively inspecting the torque tube assembly and roller bearings, and depending on the results, replacing parts or accomplishing additional inspections.

The NPRM was published in the

Federal Register

on November 18, 2025 (90 FR 51596). The NPRM was prompted by a report that additional torque tube assemblies are affected by the same unsafe condition addressed in AD 2024-23-06 and should be included in the AD action. In the NPRM, the FAA proposed to continue to require the actions of AD 2024-23-06, and also proposed to expand the applicability to include all MD Helicopters, LLC Model 369, 369A, 369D, 369E, 369F, 369FF, 369H, 369HE, 369HM, 369HS, 500N, and 600N helicopters, regardless of the torque tube part number. The FAA is issuing this AD to prevent failure of the torque tube assembly, which, if not addressed, could result in reduced controllability and loss of control of the helicopter.

Discussion of Final Airworthiness Directive

Comments

The FAA received comments from the Citizens Rulemaking Alliance. The following presents the comments received on the NPRM and the FAA's response to each comment.

Request To Justify Forgoing Notice and Comment or Issue an NPRM

The Citizens Rulemaking Alliance requested that, absent justification for finding good cause to bypass notice and comment procedures, the FAA either convert this action to an NPRM with a 30-day comment period or defer the effective date by 30 to 60 days while maintaining a parallel safety alert or special airworthiness information bulletin and highlighting voluntary compliance with the service information. The commenter asserted the FAA has not adequately justified use of the good cause exemption to bypass notice and comment and the 30-day delayed effective date.

The FAA notes the comment was submitted in response to an NPRM for which the FAA provided a 45-day comment period. This final rule is effective 35 days after its publication in the

Federal Register

. Therefore, the FAA did not change this AD as a result of this comment.

Request To Supplement the AD Docket With Supporting Data

The Citizens Rulemaking Alliance requested that the FAA add to the AD docket the FAA's risk assessment, the background report data, the dates of the triggering service information and any foreign authority AD, and a summary of alternatives considered and rejected for safety reasons. The commenter stated that this will allow commenters to address safety tradeoffs while preserving urgent mitigation if warranted.

The FAA has assessed and disclosed the background and basis for this rulemaking in the preamble of the NPRM, including a discussion of the previous AD, a description of the unsafe condition, and the FAA's rationale for the required actions on additional torque tube assemblies. This information was available to the public during the 45-day comment period provided by the NPRM.

The FAA evaluated the alternative of not promulgating this AD but ultimately determined that this alternative would create a significant safety hazard. Relying on voluntary compliance or existing requirements would leave the unsafe condition unaddressed and would not ensure an acceptable level of safety. Accordingly, the FAA has determined that promulgating this AD is necessary to ensure an acceptable level of safety.

Since the FAA has assessed and disclosed the basis for this rulemaking in the preamble of the NPRM, there is no service material or foreign authority AD related to this rulemaking action, and the commenter did not provide additional safety data for the FAA to consider in its analysis, it is not necessary to provide additional information in the AD docket.

Request To Comply With the Paperwork Reduction Act (PRA)

The Citizens Rulemaking Alliance requested that the FAA revise the proposed AD to comply with the PRA if reporting is required, or remove any reporting provisions and stay enforcement until PRA requirements are satisfied. The commenter stated that the PRA requires providing the applicable Office of Management and Budget (OMB) control number(s), required PRA statements, and burden estimates in the AD and docket. If reporting is not required, the commenter requested the FAA clarify that in the AD.

The FAA notes that this AD does not require reporting. If an AD were to require reporting, the preamble of the AD would include a paragraph titled “Paperwork Reduction Act” that would provide the applicable OMB control number, required PRA statements, and the estimated time to collect the required information (burden). Any costs associated with the reporting requirement would be included in the Costs of Compliance section in the preamble of the AD. Therefore, the FAA did not change this AD as a result of this comment.

Request To Make Incorporation by Reference (IBR) Materials Reasonably Available

The Citizens Rulemaking Alliance stated that the FAA's current practices for IBR frequently fail to meet the legal and regulatory standards for reasonable availability. The commenter called on the FAA to guarantee that all IBR materials are easily and freely accessible to the public and affected parties for both commenting and compliance purposes. They also requested that this access be documented in the rulemaking record. Further, the commenter requested that, if reasonable availability cannot be assured, enforcement of the incorporated by reference requirements be deferred until it is assured.

The FAA notes that this AD does not incorporate by reference any material. All required actions and compliance times are contained within the regulatory text of this AD. Therefore, the FAA did not change this AD as a result of this comment.

Request To Consider Impact on Small Entities

The Citizens Rulemaking Alliance requested that the FAA either provide the factual basis for its Regulatory Flexibility Act (RFA) certification that the AD will not have a significant economic impact on a substantial number of small entities or prepare an initial regulatory flexibility analysis and seek input from the Office of Advocacy from the Small Business Administration (SBA).

The FAA has considered the AD's impact on small businesses and provides the following analysis.

The Regulatory Flexibility Act of 1980, Public Law 96-354, 94 Stat. 1164 (5 U.S.C. 601-612), as amended by the Small Business Regulatory Enforcement Fairness Act of 1996 (Public Law 104-121, 110 Stat. 857, Mar. 29, 1996) and the Small Business Jobs Act of 2010 (Public Law 111-240, 124 Stat. 2504, Sept. 27, 2010), requires Federal agencies to consider the effects of the regulatory action on small business and other small entities and to minimize any significant economic impact. The term “small entities” comprises small businesses and not-for-profit organizations that are independently owned and operated and are not dominant in their fields, and governmental jurisdictions with populations of less than 50,000.

Small Entities to Which This AD Applies

The FAA used the definition of small entities in the RFA for this analysis. The RFA defines small entities as small businesses, small governmental jurisdictions, or small organizations. In 5 U.S.C. 601(3), the RFA defines “small business” to have the same meaning as “small business concern” under section 3 of the Small Business Act. The Small Business Act authorizes the SBA to define “small business” by issuing regulations.

The SBA has established size standards for various types of economic activities, or industries, under the North American Industry Classification System (NAICS). These size standards generally define small businesses based on the number of employees or annual receipts. The following table provides the SBA size standards for all industries with at least one entity

impacted by this AD. Note that the SBA definition of a small business applies to the parent company and all affiliates as a single entity.

The FAA does not have entity data for, or the entity was identified as a foreign business, 45 of the 680 affected helicopters. Those helicopters are excluded from this analysis. The number of affected helicopters has been updated in this final rule to reflect the current fleet.

Small Business Size Standards

NAICS

NAICS description

Size standard

111199

All Other Grain Farming

$2,500,000.

111332

Citrus, Except Orange, Groves

$4,000,000.

111998

All Other Miscellaneous Crop Farming

$2,500,000.

112519

Other Aquaculture

$3,750,000.

114111

Finfish Fishing

$25,000,000.

115112

Soil Preparation, Planting, and Cultivating

$9,500,000.

115116

Farm Management Services

$15,500,000.

115210

Support Activities for Animal Production

$11,000,000.

115310

Support Activities for Forestry

$11,500,000.

212321

Construction Sand and Gravel Mining

500 Employees.

213111

Drilling Oil and Gas Wells

1,000 Employees.

213112

Support Activities for Oil and Gas Operations

$47,000,000.

221111

Hydroelectric Power Generation

50,000 Employees.

221122

Electric Power Distribution

1,100 Employees.

236115

New Single-family Housing Construction

$45,000,000.

236220

Commercial and Institutional Building Construction

$45,000,000.

237110

Water and Sewer Line and Related Structures Construction

$47,000,000.

237130

Power and Communication Line and Related Structures Construction

$45,000,000.

237210

Land Subdivision

$34,000,000.

237310

Highway, Street, and Bridge Construction

$45,000,000.

238210

Electrical Contractors and Other Wiring Installation

Contractors

$19,000,000.

238220

Plumbing, Heating, and Air Conditioning Contractors

$19,000,000.

238910

Site Preparation Contractors

$19,000,000.

238990

All Other Specialty Trade Contractors

$19,000,000.

321113

Sawmills

550 Employees.

325920

Explosives Manufacturing

750 Employees.

325998

All Other Miscellaneous Chemical Product and

Preparation Manufacturing

650 Employees.

332912

Fluid Power Valve and Hose Fitting Manufacturing

1,000 Employees.

334413

Semiconductor and Related Device Manufacturing

1,250 Employees.

336212

Truck Trailer Manufacturing

1,000 Employees.

336320

Motor Vehicle Electrical and Electronic Equipment Manufacturing

1,000 Employees.

336390

Other Motor Vehicle Parts Manufacturing

1,000 Employees.

336411

Aircraft Manufacturing

1,500 Employees.

336413

Other Aircraft Parts and Auxiliary Equipment Manufacturing

1,250 Employees.

423430

Computer and Computer Peripheral Equipment and Software Merchant Wholesalers

250 Employees.

423820

Farm and Garden Machinery and Equipment Merchant Wholesalers

175 Employees.

423860

Transportation Equipment and Supplies (except Motor Vehicle) Merchant Wholesalers

175 Employees.

423990

Other Miscellaneous Durable Goods Merchant Wholesalers

1,250 Employees.

441110

New Car Dealers

200 Employees.

481111

Scheduled Passenger and Cargo Airlines Serving Western Alaska

1,500 Employees.

481112

Scheduled Freight Air Transportation

1,500 Employees.

481211

Nonscheduled Chartered Passenger Air Transportation

1,500 Employees.

481212

Nonscheduled Chartered Freight Air Transportation

1,500 Employees.

481219

Other Nonscheduled Air Transportation

$25,000,000.

484110

General Freight Trucking, Local

$34,000,000.

488119

Other Airport Operations

$40,000,000.

488190

Other Support Activities for Air Transportation

$40,000,000.

488210

Support Activities for Rail Transportation

$34,000,000.

488330

Navigational Services to Shipping

$47,000,000.

523910

Miscellaneous Intermediation

$47,000,000.

531110

Lessors of Residential Buildings and Dwellings

$34,000,000.

531120

Lessors of Nonresidential Buildings

$34,000,000.

531190

Real Estate Holding and Specific Asset (Aircraft) Management

$34,000,000.

531210

Offices of Real Estate Agents and Brokers

$15,000,000.

531311

Residential Property Managers

$12,500,000.

531312

Management of Nonresidential Real Estate

$30,000,000.

531320

Offices of Real Estate Appraisers

$9,500,000.

531390

Other Activities Related to Real Estate

$19,500,000.

532112

Passenger Car Leasing

$34,000,000.

532411

Commercial Air, Rail, and Water Transportation Equipment Rental and Leasing

$45,500,000.

532412

Construction, Mining and Forestry Machinery and Equipment Rental and Leasing

$40,000,000.

532490

Other Commercial and Industrial Machinery and Equipment Rental and Leasing

$40,000,000.

541110

Offices of Lawyers

$15,500,000.

541211

Offices of Certified Public Accountants

$26,500,000.

541330

Engineering Services

$25,500,000.

541511

Custom Computer Programming Services

$34,000,000.

541611

Administrative Management and General Management Consulting Services

$24,500,000.

541715

Research and Development in the Physical, Engineering, and Life Sciences

1,000 Employees.

541720

Research and Development in the Social Sciences and Humanities

$28,500,000.

541810

Advertising Agencies

$22,500,000.

541922

Commercial Photography

$9,000,000.

551112

Offices of Other Holding Companies

$45,500,000.

561710

Exterminating and Pest Control Services

$17,500,000.

561730

Landscaping Services

$9,500,000.

562111

Solid Waste Collection

$47,000,000.

611430

Professional and Management Development Training

$15,000,000.

611512

Flight Training

$34,000,000.

624230

Emergency and Other Relief Services

$41,500,000.

712110

Museums

$34,000,000.

713990

All Other Amusement and Recreation Industries

$9,000,000.

811210

Electronic and Precision Equipment Repair and Maintenance

$34,000,000.

813211

Grantmaking Foundations

$40,000,000.

813410

Civic and Social Organizations

$9,500,000.

921110

Executive Offices

50,000 Employees.

921120

Legislative Bodies

50,000 Employees.

922110

Law Enforcement

50,000 Employees.

922120

Law Enforcement

50,000 Employees.

922160

Fire & Rescue

50,000 Employees.

922190

Other Justice, Public Order, and Safety Activities

50,000 Employees.

924110

Government

50,000 Employees.

924120

Government

50,000 Employees.

926140

Government

50,000 Employees.

928110

Government

50,000 Employees.

928120

International Affairs

50,000 Employees.

To identify small entities, the FAA first identified the primary NAICS of the entity or parent company, and then used data from different sources (

e.g.,

company annual reports, Bureau of Transportation Statistics) to determine whether the entity meets the applicable size standard. The FAA provides the estimated number of small entities affected by this AD:

Estimated Number of Small Entities

NAICS category

Number

entities

Number of

affected

aircraft

Small

business

entities

Percent

small

entities

All Other Grain Farming

100

Citrus, except Orange, Groves

100

All Other Miscellaneous Crop Farming

100

Other Aquaculture

100

Finfish Fishing

Soil Preparation, Planting, and Cultivating

100

Farm Management Services

100

Support Activities for Animal Production

100

Support Activities for Forestry

100

Construction Sand and Gravel Mining

100

Drilling Oil and Gas Wells

100

Support Activities for Oil and Gas Operations

100

Hydroelectric Power Generation

Electric Power Distribution

100

New Single-family Housing Construction

100

Commercial and Institutional Building Construction

100

Water and Sewer Line and Related Structures Construction

100

Power and Communication Line and Related Structures Construction

Land Subdivision

Highway, Street, and Bridge Construction

100

Electrical Contractors and Other Wiring Installation Contractors

100

Plumbing, Heating, and Air Conditioning Contractors

100

Site Preparation Contractors

100

All Other Specialty Trade Contractors

Sawmills

100

Explosives Manufacturing

100

All Other Miscellaneous Chemical Product and Preparation Manufacturing

Fluid Power Valve and Hose Fitting Manufacturing

100

Semiconductor and Related Device Manufacturing

100

Truck Trailer Manufacturing

Motor Vehicle Electrical and Electronic Equipment Manufacturing

100

Other Motor Vehicle Parts Manufacturing

100

Aircraft Manufacturing

Other Aircraft Parts and Auxiliary Equipment Manufacturing

100

Computer and Computer Peripheral Equipment and Software Merchant Wholesalers

100

Farm and Garden Machinery and Equipment Merchant Wholesalers

Transportation Equipment and Supplies (except Motor Vehicle) Merchant Wholesalers

100

Other Miscellaneous Durable Goods Merchant Wholesalers

New Car Dealer

100

Scheduled Passenger and Cargo Airline Serving Western Alaska

100

Scheduled Freight Air Transportation

100

Nonscheduled Chartered Passenger Air Transportation

165

Nonscheduled Chartered Freight Air Transportation

100

Other Nonscheduled Air Transportation

General Freight Trucking, Local

100

Other Airport Operations

100

Other Support Activities for Air Transportation

Support Activities for Rail Transportation

100

Navigational Services to Shipping

100

Miscellaneous Intermediation

100

Lessors of Residential Buildings and Dwellings

Lessors of Nonresidential Buildings

100

Real Estate Holding and Specific Asset (Aircraft) Management

100

Offices of Real Estate Agents and Brokers

Residential Property Managers

100

Management of Nonresidential Real Estate

100

Offices of Real Estate Appraisers

100

Other Activities Related to Real Estate

100

Passenger Car Leasing

100

Commercial Air, Rail, and Water Transportation Equipment Rental and Leasing

Construction, Mining and Forestry Machinery and Equipment Rental and Leasing

100

Other Commercial and Industrial Machinery and Equipment Rental and Leasing

100

Offices of Lawyers

100

Offices of Certified Public Accountants

100

Engineering Services

100

Custom Computer Programming Services

100

Administrative Management and General Management Consulting Services

100

Research and Development in the Physical, Engineering, and Life Sciences

100

Research and Development in the Social Sciences and Humanities

100

Advertising Agencies

100

Commercial Photography

100

Offices of Other Holding Companies

100

Exterminating and Pest Control Services

Landscaping Services

Solid Waste Collection

Professional and Management Development Training

Flight Training

100

Emergency and Other Relief Services

100

Museums

All Other Amusement and Recreation Industries

100

Electronic and Precision Equipment Repair and Maintenance

100

Grantmaking Foundations

100

Civic and Social Organizations

Executive Offices

Legislative Bodies

Law Enforcement

Fire & Rescue

Other Justice, Public Order, and Safety Activities

Government

International Affairs

Total

336

635

263

Projected Reporting, Recordkeeping, and Other Compliance Requirements

The FAA estimates affected entities will incur an inspection cost of $149 per inspection cycle, with an average of 7 inspection cycles per year. FAA analyzes the cost of inspection of $1,043 as the low-case for each small entity. Based upon the results of the inspections, operators could incur up to 3 on-condition costs of $6,024. If an operator were to incur all inspection and on-condition costs, FAA estimates each operator would incur $7,067 per helicopter annually. The FAA has no way to determine if each helicopter will require these on-condition costs. The high-case includes both inspection and on-condition costs for each small entity. The following table presents the small entity case burdens average percentage for compliance based on the average annual revenue by each NAICS industry.

Number of Small Entities Affected by Industry and Cost Significance

NAICS

description

Number of

operators

Average

annual

revenue

Number of

aircraft

affected

Low-Case

burden

average

(%)

High-Case

burden

average

(%)

111199

All Other Grain Farming

$315,780

0.33%

2.24%

111332

Citrus, except Orange, Groves

286,790

0.73

4.93

114111

Finfish Fishing

600,000

0.17

1.18

115112

Soil Preparation, Planting, and Cultivating

526,180

0.33

2.22

115116

Farm Management Services

158,020

0.66

4.47

115210

Support Activities for Animal Production

356,057

0.92

6.23

115310

Support Activities for Forestry

625,705

0.30

2.02

212321

Construction Sand and Gravel Mining

520,000

0.20

1.36

213111

Drilling Oil and Gas Wells

1,680,000

0.06

0.42

213112

Support Activities for Oil and Gas Operations

246,800

0.42

2.86

221122

Electric Power Distribution

700,000

0.15

1.01

236115

New Single-family Housing Construction

104,160

1.00

6.78

236220

Commercial and Institutional Building Construction

575,330

0.54

3.66

237110

Water and Sewer Line and Related Structures Construction

5,580,000

0.02

0.13

237210

Land Subdivision

61,020

1.71

11.58

237310

Highway, Street, and Bridge Construction

6,138,005

0.69

4.68

238210

Electrical Contractors and Other Wiring Installation Contractors

6,410,000

0.18

1.21

238910

Site Preparation Contractors

950,000

0.11

0.74

321113

Sawmills

156,710

0.67

4.51

325920

Explosives Manufacturing

1,210,000

0.09

0.58

334413

Semiconductor and Related Device Manufacturing

245,810

0.42

2.87

336320

Motor Vehicle Electrical and Electronic Equipment Manufacturing

163,600

0.64

4.32

336411

Aircraft Manufacturing

1,182,320

2.44

16.55

336413

Other Aircraft Parts and Auxiliary Equipment Manufacturing

235,005

0.95

6.43

423430

Computer and Computer Peripheral Equipment and Software Merchant Wholesalers

11,160,000

0.01

0.06

423860

Transportation Equipment and Supplies (except Motor Vehicle) Merchant Wholesalers

3,202,923

0.42

2.84

441110

New Car Dealer

214,510

0.49

3.29

481111

Scheduled passenger and cargo airline serving Western Alaska

6,960,000

0.04

0.30

481112

Scheduled Freight Air Transportation

260,960

0.40

2.71

481211

Nonscheduled Chartered Passenger Air Transportation

1,723,034

142

0.97

6.56

481212

Nonscheduled Chartered Freight Air Transportation

2,202,997

0.35

2.34

481219

Other Nonscheduled Air Transportation

465,218

0.57

3.89

484110

General Freight Trucking, Local

2,860,000

0.04

0.25

488119

Other Airport Operations

396,330

0.90

6.12

488190

Other Support Activities for Air Transportation

955,989

0.58

3.90

488210

Support Activities for Rail Transportation

73,270

1.42

9.65

488330

Navigational Services to Shipping

267,710

0.39

2.64

523910

Miscellaneous Intermediation

120,155

1.02

6.90

531110

Lessors of Residential Buildings and Dwellings

114,980

0.91

6.15

531120

Lessors of Nonresidential Buildings

214,985

1.12

7.57

531312

Management of Nonresidential Real Estate

329,080

0.32

2.15

531320

Offices of Real Estate Appraisers

1,020,000

0.10

0.69

531390

Other Activities Related to Real Estate

120,580

1.13

7.63

532112

Passenger Car Leasing

65,270

1.60

10.83

532411

Commercial Air, Rail, and Water Transportation Equipment Rental and Leasing

434,369

0.37

2.51

532412

Construction, Mining and Forestry Machinery and Equipment Rental and Leasing

234,180

2.23

15.09

532490

Other Commercial and Industrial Machinery and Equipment Rental and Leasing

106,700

0.98

6.62

541110

Offices of Lawyers

33,720

6.19

41.92

541330

Engineering Services

206,827

0.61

4.13

541511

Custom Computer Programming

42,000

2.48

16.83

541611

Administrative Management and General Management Consulting Services

250,367

0.94

6.36

541922

Commercial Photography

326,530

0.32

2.16

551112

Offices of Other Holding Companies

318,350

0.49

3.31

561730

Landscaping Services

133,680

0.78

5.29

611512

Flight Training

565,947

0.51

3.47

712110

History Museum & Education (501c3)

65,315

1.64

11.14

922110

Law Enforcement

116,229,610

0.00

0.02

922120

Law Enforcement

327,012,029

0.00

624230

Emergency and Other Relief Services

431,150

0.24

1.64

713990

All Other Amusement and Recreation Industries

346,990

0.30

2.04

Source: Dun & Bradstreet, D&B Hoovers, retrieved April 28, 2024,

app.hoovers.dnb.com;

ZoomInfo, ZoomInfo Technologie Inc., retrieved April 28, 2024,

zoominfo.com.

Note:

NAICS codes with only one entity equals the number of aircraft.

Example: NAICS 115310 has two operators with a total of three aircraft affected. Operator 1 calculations: Low Case Burden ($2,086/$980,000) = 0.21%. Operator 2 calculations: Low Case Burden ($1,043/$271,410) = 0.38%. The average Low Case Burden is (0.21% + 0.38%)/2 = 0.30%. The same method was used to calculate the High Case Burden. All NAICS with multiple operators use the same method of calculation.

Significant Alternatives Considered

The FAA evaluated the alternative of not promulgating this AD but ultimately deemed that this alternative would create a significant safety hazard. Since the issuance of AD 2024-23-06, which affected certain MD Helicopters, LLC Model 369, 369A, 369D, 369E, 369F, 369FF, 369H, 369HE, 369HM, 369HS, 500N, and 600N helicopters, it has been determined that the risk of failure of the torque tube assembly extends to additional torque tube assemblies. Relying on the existing requirements would leave these additional torque tube assemblies unmonitored. By expanding the applicability, this AD addresses the unsafe condition and prevents potential failure, ensuring a level of safety that the alternative of no action could not provide.

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, replacement of the RFA certification with a final regulatory flexibility analysis, a change in the Costs of Compliance section (from 353 helicopters to 680 helicopters and corresponding cost changes), and any 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.

Costs of Compliance

The FAA estimates that this AD affects 680 helicopters of U.S. registry. The FAA estimates the following costs to comply with this AD:

Estimated Costs

Action

Labor cost

Parts

cost

Cost per product

Cost on U.S.

operators

Visual inspection of torque tube and roller bearings

1 work-hour × $85 per hour = $85, per inspection cycle

$85, per inspection cycle

$57,800, per inspection cycle.

Inspection of torque tube for freedom-of-movement

0.75 work-hour × $85 per hour = $64, per inspection cycle

$64, per inspection cycle

$43,520, per inspection cycle.

The FAA estimated operators will incur $85 in costs per labor hour, which is the weighted average fiscal year (FY) 2026 fully loaded wage of an aircraft mechanic ($69.85) working 60 percent of the labor hours and a general and operations manager ($108.15) working 40 percent of the labor hours. The FAA estimated these wages by taking the average of the FY 2024 Bureau of Labor Statistics (BLS) air transportation industry average wage for aircraft mechanics and general and operations managers (See: Occupational Employment and Wage Statistics Query System, BLS (May 2024),

data.bls.gov/oes/

); multiplying each wage by a fringe benefit factor of 1.42 (See: Employer Cost for Employee Compensation—December 2024, BLS (2024),

bls.gov/news.release/archives/ecec_03142025.pdf

); and adjusting these 2024 wages to 2026 dollars using an implicit Gross Domestic Product (GDP) Price Deflator of 2.8 percent (See: Gross Domestic Product: Implicit Price Deflator, FRED (2026)

fred.stlouisfed.org/series/GDPDEF

The FAA estimates the following costs to do any on-condition actions that would be required based on the results of the inspections. The agency has no way of determining the number of helicopters that might need these on-condition actions:

On-Condition Costs

Action

Labor cost

Parts cost

Cost per

product

Replacement of torque tube

6 work-hours × $85 per hour = $510

$4,773

$5,283

Visual inspection of roller bearings

0.25 work-hour × $85 per hour = $21

Replacement of roller bearing

6 work-hours × $85 per hour = $510

210

720

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, and

(2) Will not affect intrastate aviation in Alaska.

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:

a. Removing Airworthiness Directive 2024-23-06, Amendment 39-22885 (89 FR 91248, November 19, 2024); and

b. Adding the following new airworthiness directive:

MD Helicopters, LLC:

Docket No. FAA-2025-3987; Project Identifier AD-2025-00017-R.

(a) Effective Date

This airworthiness directive (AD) is effective October 20, 2026.

(b) Affected ADs

This AD replaces AD 2024-23-06, Amendment 39-22885 (89 FR 91248, November 19, 2024) (AD 2024-23-06).

This AD applies to all MD Helicopters, LLC Model 369, 369A, 369D, 369E, 369F, 369FF, 369H, 369HE, 369HM, 369HS, 500N, and 600N helicopters, certificated in any category.

(d) Subject

Joint Aircraft System Component (JASC) Code 6700, Rotorcraft flight control.

(e) Unsafe Condition

This AD was prompted by a report of a seized and damaged roller bearing assembly in the torque tube assembly. The FAA is issuing this AD to prevent failure of the torque tube assembly. The unsafe condition, if not addressed, could result in reduced controllability and 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 100 hours time-in-service (TIS) or within 12 months after the effective date of this AD, whichever occurs first, and thereafter at intervals not to exceed 100 hours TIS, accomplish the actions required by paragraphs (g)(1)(i) and (ii) of this AD.

(i) Using a flashlight and mirror, visually inspect the torque tube for corrosion and cracks. If there is any corrosion or a crack, before further flight, remove the torque tube

from service and install an airworthy torque tube.

(ii) Visually inspect each roller bearing (number 5) as depicted in Figure 1 to paragraph (g)(1) of this AD for corrosion and degradation. If a roller bearing has any corrosion or degradation, before further flight, remove the roller bearing from service and install an airworthy roller bearing.

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Figure 1 to Paragraph (g)(1)—Torque Tube Assembly

ER15SE26.013

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(2) Before the helicopter accumulates 3,000 total hours TIS or within 100 hours TIS after the effective date of this AD, whichever occurs later, and thereafter at intervals not to exceed 100 hours TIS, perform a freedom-of-movement inspection on the torque tube assembly by accomplishing the actions required by paragraphs (g)(2)(i) through (v) of this AD.

(i) Disconnect the one-way lock (number 6) of the torque tube by removing the cotter pin (number 7), nut (number 8), bolt (number 9), washers (number 10), and slotted bushing (number 11) from the torque tube assembly as depicted in Figure 1 to paragraph (g)(1) of this AD.

(ii) Loosen the longitudinal cyclic friction knob (number 12 or 13) of the torque tube assembly as depicted in Figure 1 to paragraph (g)(1) of this AD.

(iii) While moving the cyclic control forward and aft to allow the torque tube assembly to rotate through its full range of motion, inspect the torque tube assembly for binding and ratcheting.

(A) If there is any binding or ratcheting as a result of the action required by paragraph (g)(2)(iii) of this AD, before further flight, inspect each roller bearing (number 5) as depicted in Figure 1 to paragraph (g)(1) of this AD for damage. For the purposes of this inspection, damage may be indicated by corrosion, lack of lubrication (dry exterior surface), or material degradation.

(B) If any roller bearing (number 5) as depicted in Figure 1 to paragraph (g)(1) of this AD has any damage, before further flight, remove the roller bearing from service and install an airworthy roller bearing.

(iv) If there is not any binding or ratcheting as a result of the action required by paragraph (g)(2)(iii) of this AD or after accomplishing the action required by paragraph (g)(2)(iii)(B) of this AD, as applicable, tighten the cyclic friction knob (number 12 or 13) as depicted in Figure 1 to paragraph (g)(1) of this AD.

(v) Connect the one-way lock (number 6) as depicted in Figure 1 to paragraph (g)(1) of this AD by accomplishing the actions required by paragraphs (g)(2)(v)(A) and (B).

(A) Install the slotted bushing (number 11), washers (number 10), bolt (number 9), nut (number 8), and new (zero total hours TIS) cotter pin (number 7) as depicted in Figure 1 to paragraph (g)(1) of this AD.

(B) Ensure the edge of the slotted bushing (number 11) protrudes 0.010 to 0.080 inch (0.25 to 2.03 millimeters) above the surface of the cyclic torque tube after the nut is tightened.

(h) Alternative Methods of Compliance (AMOCs)

(1) The Manager, West 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 responsible Flight Standards Office, as appropriate. If sending information directly to the manager of the West Certification Branch, send it to the attention of the person identified in paragraph (i) of this AD and email 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.

(i) Additional Information

For more information about this AD, contact Eduardo Orozco-Duran, Aviation Safety Engineer, FAA, 3960 Paramount Boulevard, Lakewood, CA 90712; phone: (562) 627-5264; email:

eduardo.orozco-duran@faa.gov

(j) Material Incorporated by Reference

None.

Issued on September 11, 2026.

Hollister B. Thorson,

Acting Deputy Director, Compliance & Airworthiness Division, Aircraft Certification Service.

[FR Doc. 2026-18927 Filed 9-14-26; 8:45 am]

BILLING CODE 4910-13-P

This is a copy of a public record, reproduced as it was published. It is not legal advice, and it may not be the version a court would rely on. Check the official source before you cite it.