Airworthiness Directives; MD Helicopters, LLC Helicopters
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.
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.
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.
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.
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.
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.
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.
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.
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.
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 1 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.
1 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.
| 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:
| NAICS category | Number entities | Number of affected aircraft | Small business entities | Percent small entities |
|---|---|---|---|---|
| All Other Grain Farming | 1 | 1 | 1 | 100 |
| Citrus, except Orange, Groves | 1 | 1 | 1 | 100 |
| All Other Miscellaneous Crop Farming | 1 | 2 | 1 | 100 |
| Other Aquaculture | 1 | 1 | 1 | 100 |
| Finfish Fishing | 2 | 2 | 1 | 50 |
| Soil Preparation, Planting, and Cultivating | 9 | 12 | 9 | 100 |
| Farm Management Services | 1 | 1 | 1 | 100 |
| Support Activities for Animal Production | 3 | 6 | 3 | 100 |
| Support Activities for Forestry | 3 | 4 | 3 | 100 |
| Construction Sand and Gravel Mining | 1 | 1 | 1 | 100 |
| Drilling Oil and Gas Wells | 1 | 1 | 1 | 100 |
| Support Activities for Oil and Gas Operations | 1 | 1 | 1 | 100 |
| Hydroelectric Power Generation | 1 | 4 | 0 | 0 |
| Electric Power Distribution | 1 | 1 | 1 | 100 |
| New Single-family Housing Construction | 2 | 2 | 2 | 100 |
| Commercial and Institutional Building Construction | 2 | 7 | 2 | 100 |
| Water and Sewer Line and Related Structures Construction | 1 | 1 | 1 | 100 |
| Power and Communication Line and Related Structures Construction | 1 | 6 | 0 | 0 |
| Land Subdivision | 3 | 3 | 2 | 67 |
| Highway, Street, and Bridge Construction | 2 | 2 | 2 | 100 |
| Electrical Contractors and Other Wiring Installation Contractors | 1 | 11 | 1 | 100 |
| Plumbing, Heating, and Air Conditioning Contractors | 1 | 1 | 1 | 100 |
| Site Preparation Contractors | 1 | 1 | 1 | 100 |
| All Other Specialty Trade Contractors | 1 | 1 | 0 | 0 |
| Sawmills | 1 | 1 | 1 | 100 |
| Explosives Manufacturing | 1 | 1 | 1 | 100 |
| All Other Miscellaneous Chemical Product and Preparation Manufacturing | 1 | 1 | 0 | 0 |
| Fluid Power Valve and Hose Fitting Manufacturing | 1 | 1 | 1 | 100 |
| Semiconductor and Related Device Manufacturing | 1 | 1 | 1 | 100 |
| Truck Trailer Manufacturing | 1 | 1 | 0 | 0 |
| Motor Vehicle Electrical and Electronic Equipment Manufacturing | 1 | 1 | 1 | 100 |
| Other Motor Vehicle Parts Manufacturing | 1 | 1 | 1 | 100 |
| Aircraft Manufacturing | 6 | 16 | 2 | 33 |
| Other Aircraft Parts and Auxiliary Equipment Manufacturing | 3 | 3 | 3 | 100 |
| Computer and Computer Peripheral Equipment and Software Merchant Wholesalers | 1 | 1 | 1 | 100 |
| Farm and Garden Machinery and Equipment Merchant Wholesalers | 1 | 1 | 0 | 0 |
| Transportation Equipment and Supplies (except Motor Vehicle) Merchant Wholesalers | 3 | 4 | 3 | 100 |
| Other Miscellaneous Durable Goods Merchant Wholesalers | 1 | 1 | 0 | 0 |
| New Car Dealer | 1 | 1 | 1 | 100 |
| Scheduled Passenger and Cargo Airline Serving Western Alaska | 1 | 3 | 1 | 100 |
| Scheduled Freight Air Transportation | 2 | 2 | 2 | 100 |
| Nonscheduled Chartered Passenger Air Transportation | 79 | 165 | 75 | 95 |
| Nonscheduled Chartered Freight Air Transportation | 8 | 16 | 8 | 100 |
| Other Nonscheduled Air Transportation | 17 | 35 | 15 | 88 |
| General Freight Trucking, Local | 1 | 1 | 1 | 100 |
| Other Airport Operations | 4 | 4 | 4 | 100 |
| Other Support Activities for Air Transportation | 31 | 60 | 30 | 97 |
| Support Activities for Rail Transportation | 1 | 1 | 1 | 100 |
| Navigational Services to Shipping | 1 | 1 | 1 | 100 |
| Miscellaneous Intermediation | 2 | 2 | 2 | 100 |
| Lessors of Residential Buildings and Dwellings | 3 | 3 | 2 | 67 |
| Lessors of Nonresidential Buildings | 2 | 2 | 2 | 100 |
| Real Estate Holding and Specific Asset (Aircraft) Management | 1 | 1 | 1 | 100 |
| Offices of Real Estate Agents and Brokers | 1 | 1 | 0 | 0 |
| Residential Property Managers | 1 | 2 | 1 | 100 |
| Management of Nonresidential Real Estate | 1 | 1 | 1 | 100 |
| Offices of Real Estate Appraisers | 1 | 1 | 1 | 100 |
| Other Activities Related to Real Estate | 3 | 3 | 3 | 100 |
| Passenger Car Leasing | 1 | 1 | 1 | 100 |
| Commercial Air, Rail, and Water Transportation Equipment Rental and Leasing | 16 | 19 | 15 | 94 |
| Construction, Mining and Forestry Machinery and Equipment Rental and Leasing | 1 | 5 | 1 | 100 |
| Other Commercial and Industrial Machinery and Equipment Rental and Leasing | 2 | 2 | 2 | 100 |
| Offices of Lawyers | 4 | 5 | 4 | 100 |
| Offices of Certified Public Accountants | 1 | 1 | 1 | 100 |
| Engineering Services | 3 | 3 | 3 | 100 |
| Custom Computer Programming Services | 2 | 2 | 2 | 100 |
| Administrative Management and General Management Consulting Services | 6 | 6 | 6 | 100 |
| Research and Development in the Physical, Engineering, and Life Sciences | 1 | 1 | 1 | 100 |
| Research and Development in the Social Sciences and Humanities | 1 | 1 | 1 | 100 |
| Advertising Agencies | 1 | 1 | 1 | 100 |
| Commercial Photography | 1 | 1 | 1 | 100 |
| Offices of Other Holding Companies | 4 | 5 | 4 | 100 |
| Exterminating and Pest Control Services | 3 | 4 | 0 | 0 |
| Landscaping Services | 2 | 12 | 1 | 50 |
| Solid Waste Collection | 1 | 1 | 0 | 0 |
| Professional and Management Development Training | 1 | 1 | 0 | 0 |
| Flight Training | 7 | 8 | 7 | 100 |
| Emergency and Other Relief Services | 1 | 1 | 1 | 100 |
| Museums | 3 | 3 | 2 | 67 |
| All Other Amusement and Recreation Industries | 1 | 1 | 1 | 100 |
| Electronic and Precision Equipment Repair and Maintenance | 1 | 1 | 1 | 100 |
| Grantmaking Foundations | 1 | 1 | 1 | 100 |
| Civic and Social Organizations | 1 | 1 | 0 | 0 |
| Executive Offices | 4 | 10 | 0 | 0 |
| Legislative Bodies | 1 | 1 | 0 | 0 |
| Law Enforcement | 18 | 40 | 1 | 6 |
| Law Enforcement | 10 | 21 | 1 | 10 |
| Fire & Rescue | 3 | 7 | 0 | 0 |
| Other Justice, Public Order, and Safety Activities | 2 | 6 | 0 | 0 |
| Government | 1 | 1 | 0 | 0 |
| Government | 2 | 2 | 0 | 0 |
| Government | 1 | 1 | 0 | 0 |
| Government | 1 | 45 | 0 | 0 |
| International Affairs | 1 | 2 | 0 | 0 |
| Total | 336 | 635 | 263 | 78 |
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.
| NAICS | NAICS description | Number of operators | Average annual revenue 1 | Number of aircraft affected | Low-Case burden average (%) | High-Case burden average (%) |
|---|---|---|---|---|---|---|
| 111199 | All Other Grain Farming | 1 | $315,780 | 1 | 0.33% | 2.24% |
| 111332 | Citrus, except Orange, Groves | 1 | 286,790 | 2 | 0.73 | 4.93 |
| 114111 | Finfish Fishing | 1 | 600,000 | 1 | 0.17 | 1.18 |
| 115112 | Soil Preparation, Planting, and Cultivating | 7 | 526,180 | 10 | 0.33 | 2.22 |
| 115116 | Farm Management Services | 1 | 158,020 | 1 | 0.66 | 4.47 |
| 115210 | Support Activities for Animal Production | 3 | 356,057 | 6 | 0.92 | 6.23 |
| 115310 | Support Activities for Forestry 3 | 2 | 625,705 | 3 | 0.30 | 2.02 |
| 212321 | Construction Sand and Gravel Mining | 1 | 520,000 | 1 | 0.20 | 1.36 |
| 213111 | Drilling Oil and Gas Wells | 1 | 1,680,000 | 1 | 0.06 | 0.42 |
| 213112 | Support Activities for Oil and Gas Operations | 1 | 246,800 | 1 | 0.42 | 2.86 |
| 221122 | Electric Power Distribution | 1 | 700,000 | 1 | 0.15 | 1.01 |
| 236115 | New Single-family Housing Construction | 1 | 104,160 | 1 | 1.00 | 6.78 |
| 236220 | Commercial and Institutional Building Construction | 2 | 575,330 | 7 | 0.54 | 3.66 |
| 237110 | Water and Sewer Line and Related Structures Construction | 1 | 5,580,000 | 1 | 0.02 | 0.13 |
| 237210 | Land Subdivision | 1 | 61,020 | 1 | 1.71 | 11.58 |
| 237310 | Highway, Street, and Bridge Construction | 2 | 6,138,005 | 2 | 0.69 | 4.68 |
| 238210 | Electrical Contractors and Other Wiring Installation Contractors | 1 | 6,410,000 | 11 | 0.18 | 1.21 |
| 238910 | Site Preparation Contractors | 1 | 950,000 | 1 | 0.11 | 0.74 |
| 321113 | Sawmills | 1 | 156,710 | 1 | 0.67 | 4.51 |
| 325920 | Explosives Manufacturing | 1 | 1,210,000 | 1 | 0.09 | 0.58 |
| 334413 | Semiconductor and Related Device Manufacturing | 1 | 245,810 | 1 | 0.42 | 2.87 |
| 336320 | Motor Vehicle Electrical and Electronic Equipment Manufacturing | 1 | 163,600 | 1 | 0.64 | 4.32 |
| 336411 | Aircraft Manufacturing | 2 | 1,182,320 | 4 | 2.44 | 16.55 |
| 336413 | Other Aircraft Parts and Auxiliary Equipment Manufacturing | 2 | 235,005 | 2 | 0.95 | 6.43 |
| 423430 | Computer and Computer Peripheral Equipment and Software Merchant Wholesalers | 1 | 11,160,000 | 1 | 0.01 | 0.06 |
| 423860 | Transportation Equipment and Supplies (except Motor Vehicle) Merchant Wholesalers | 3 | 3,202,923 | 4 | 0.42 | 2.84 |
| 441110 | New Car Dealer | 1 | 214,510 | 1 | 0.49 | 3.29 |
| 481111 | Scheduled passenger and cargo airline serving Western Alaska | 1 | 6,960,000 | 3 | 0.04 | 0.30 |
| 481112 | Scheduled Freight Air Transportation | 1 | 260,960 | 1 | 0.40 | 2.71 |
| 481211 | Nonscheduled Chartered Passenger Air Transportation | 61 | 1,723,034 | 142 | 0.97 | 6.56 |
| 481212 | Nonscheduled Chartered Freight Air Transportation | 6 | 2,202,997 | 14 | 0.35 | 2.34 |
| 481219 | Other Nonscheduled Air Transportation | 8 | 465,218 | 13 | 0.57 | 3.89 |
| 484110 | General Freight Trucking, Local | 1 | 2,860,000 | 1 | 0.04 | 0.25 |
| 488119 | Other Airport Operations | 2 | 396,330 | 2 | 0.90 | 6.12 |
| 488190 | Other Support Activities for Air Transportation | 23 | 955,989 | 52 | 0.58 | 3.90 |
| 488210 | Support Activities for Rail Transportation | 1 | 73,270 | 1 | 1.42 | 9.65 |
| 488330 | Navigational Services to Shipping | 1 | 267,710 | 1 | 0.39 | 2.64 |
| 523910 | Miscellaneous Intermediation | 2 | 120,155 | 2 | 1.02 | 6.90 |
| 531110 | Lessors of Residential Buildings and Dwellings | 1 | 114,980 | 1 | 0.91 | 6.15 |
| 531120 | Lessors of Nonresidential Buildings | 2 | 214,985 | 2 | 1.12 | 7.57 |
| 531312 | Management of Nonresidential Real Estate | 1 | 329,080 | 1 | 0.32 | 2.15 |
| 531320 | Offices of Real Estate Appraisers | 1 | 1,020,000 | 1 | 0.10 | 0.69 |
| 531390 | Other Activities Related to Real Estate | 2 | 120,580 | 2 | 1.13 | 7.63 |
| 532112 | Passenger Car Leasing | 1 | 65,270 | 1 | 1.60 | 10.83 |
| 532411 | Commercial Air, Rail, and Water Transportation Equipment Rental and Leasing | 11 | 434,369 | 14 | 0.37 | 2.51 |
| 532412 | Construction, Mining and Forestry Machinery and Equipment Rental and Leasing | 1 | 234,180 | 5 | 2.23 | 15.09 |
| 532490 | Other Commercial and Industrial Machinery and Equipment Rental and Leasing | 1 | 106,700 | 1 | 0.98 | 6.62 |
| 541110 | Offices of Lawyers | 1 | 33,720 | 2 | 6.19 | 41.92 |
| 541330 | Engineering Services | 3 | 206,827 | 3 | 0.61 | 4.13 |
| 541511 | Custom Computer Programming | 1 | 42,000 | 1 | 2.48 | 16.83 |
| 541611 | Administrative Management and General Management Consulting Services | 3 | 250,367 | 3 | 0.94 | 6.36 |
| 541922 | Commercial Photography | 1 | 326,530 | 1 | 0.32 | 2.16 |
| 551112 | Offices of Other Holding Companies | 2 | 318,350 | 3 | 0.49 | 3.31 |
| 561730 | Landscaping Services | 1 | 133,680 | 1 | 0.78 | 5.29 |
| 611512 | Flight Training | 7 | 565,947 | 8 | 0.51 | 3.47 |
| 712110 | History Museum & Education (501c3) | 2 | 65,315 | 2 | 1.64 | 11.14 |
| 922110 | Law Enforcement | 1 | 116,229,610 | 3 | 0.00 | 0.02 |
| 922120 | Law Enforcement | 2 | 327,012,029 | 2 | 0.00 | 0.00 |
| 624230 | Emergency and Other Relief Services | 1 | 431,150 | 1 | 0.24 | 1.64 |
| 713990 | All Other Amusement and Recreation Industries | 1 | 346,990 | 1 | 0.30 | 2.04 |
1 Source: Dun & Bradstreet, D&B Hoovers, retrieved April 28, 2024, app.hoovers.dnb.com; ZoomInfo, ZoomInfo Technologie Inc., retrieved April 28, 2024, zoominfo.com.
2 Note: NAICS codes with only one entity equals the number of aircraft.
3 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.
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.
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.
The FAA estimates that this AD affects 680 helicopters of U.S. registry. The FAA estimates the following costs to comply with this AD:
| Action | Labor cost 1 | 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 | $0 | $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 | 0 | $64, per inspection cycle | $43,520, per inspection cycle. |
1 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:
| 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 | 0 | 21 |
| Replacement of roller bearing | 6 work-hours × $85 per hour = $510 | 210 | 720 |
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.
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.
Accordingly, under the authority delegated to me by the Administrator, the FAA amends 14 CFR part 39 as follows:
1. The authority citation for part 39 continues to read as follows:
Authority:
49 U.S.C. 106(g), 40113, 44701.
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.
This airworthiness directive (AD) is effective October 20, 2026.
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.
Joint Aircraft System Component (JASC) Code 6700, Rotorcraft flight control.
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.
Comply with this AD within the compliance times specified, unless already done.
(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.
(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.
(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.
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.
None.