AD 76-03-02
Applicability
| Type | Manufacturer | Model | Details |
|---|---|---|---|
| aircraft | Sikorsky Aircraft Corporation | S-61L | Airworthiness Directives; Sikorsky Models S-61L, S-61N, S- 61NM, and S-61R Helicopters Including Military CH-3C, HH-3C, CH- 3E, and HH-3E Helicopters |
| aircraft | Sikorsky Aircraft Corporation | S-61N | Airworthiness Directives; Sikorsky Models S-61L, S-61N, S- 61NM, and S-61R Helicopters Including Military CH-3C, HH-3C, CH- 3E, and HH-3E Helicopters |
| aircraft | Sikorsky Aircraft Corporation | S-61NM | Airworthiness Directives; Sikorsky Models S-61L, S-61N, S- 61NM, and S-61R Helicopters Including Military CH-3C, HH-3C, CH- 3E, and HH-3E Helicopters |
| aircraft | Sikorsky Aircraft Corporation | S-61R | Airworthiness Directives; Sikorsky Models S-61L, S-61N, S- 61NM, and S-61R Helicopters Including Military CH-3C, HH-3C, CH- 3E, and HH-3E Helicopters |
Unsafe Condition
Fractures in NAS 577-10 or NAS 577-10A barrel nuts used for attaching the transmission main gearbox to the fuselage structure.
AI-generated summary from the source AD text. Verify against the official source before acting.
Required Actions
Remove NAS 577-10 or NAS 577-10A barrel nuts and replace with RMLH 2577-108 barrel nuts.
AI-generated summary from the source AD text. Verify against the official source before acting.
Compliance Time
within the next 30 days after the effective date of this AD
AI-generated summary from the source AD text. Verify against the official source before acting.
Affected Aircraft
Sikorsky Models S-61L, S-61N, S-61NM, S-61R helicopters including Military CH-3C, HH-3C, CH-3E, and HH-3E helicopters using NAS 577-10 or NAS 577-10A barrel nuts.
AI-generated summary from the source AD text. Verify against the official source before acting.
Federal Register Abstract
Fractures in Barrel Nuts
Applicability Source Text
Show captured applicability text from the source AD
AD Final Rules - DRS_76-03-02.html Copy URL Print/Save as PDF Document Versions Feedback Details AD Number: 76-03-02 Document Type: AD Final Rules Docket Number: Unknown Subject Heading: Airworthiness Directives; Sikorsky Models S-61L, S-61N, S- 61NM, and S-61R Helicopters Including Mil...Show more Subject: Fractures in Barrel Nuts Status: Current Citation: This information is not available. Citation Publish Date: Effective Date: 02/17/1976 Make: Sikorsky Aircraft Corporation Model: S-61L | S-61N | S-61NM | S-61R Product Type: Aircraft Product Subtype: Rotorcraft Affected AD: Superseded AD: Affected By: Superseded By: Service/Office: Office of Primary Responsibility: CFR Part Reference: Part 39 Comments: AIRWORTHINESS DIRECTIVES FINAL RULES: 76-03-02 CITATION: This information is not available. PAGE NUMBER: DOCKET NUMBER: Unknown AMENDMENT: 39-2507 AD NUMBER: 76-03-02 SUBJECT HEADING: Airworthiness Directives; Sikorsky Models S-61L, S-61N, S- 61NM, and S-61R Helicopters Including Military CH-3C, HH-3C, CH- 3E, and HH-3E Helicopters ACTION: SUMMARY: DATES: Effective February 17, 1976. ADDRESSES: FOR FURTHER INFORMATION CONTACT: SUPPLEMENTARY INFORMATION: REGULATORY TEXT: 76-03-02 SIKORSKY AIRCRAFT: Amendment 39-2507. Applies to S-61L, S-61N, S- 61NM, and S-61R helicopters certified in all categories including Military CH-3C, HH-3C, CH- 3E, and HH-3E helicopters using NAS 577-10 or NAS 577-10A barrel nuts for attaching the transmission main gearbox to the fuselage structure. Compliance required as indicated. To prevent fractures in the attaching nuts accomplish the following: Remove the NAS 577-10 or NAS 577-10A barrel nuts and replace with RMLH 2577-108 barrel nuts within the next 30 days after the effective date of this AD, unless already accomplished. (NOTE: Sikorsky Service Bulletin No. 61B35-36B covers this subject.) This supersedes Amendment 39-2202 (40 FR 24355), AD 75-12-13. This amendment becomes effective February 17, 1976. FOOTER:
Document Text
Show stored source text (verify against official source)
AD Final Rules - DRS_76-03-02.html Copy URL Print/Save as PDF Document Versions Feedback Details AD Number: 76-03-02 Document Type: AD Final Rules Docket Number: Unknown Subject Heading: Airworthiness Directives; Sikorsky Models S-61L, S-61N, S- 61NM, and S-61R Helicopters Including Mil...Show more Subject: Fractures in Barrel Nuts Status: Current Citation: This information is not available. Citation Publish Date: Effective Date: 02/17/1976 Make: Sikorsky Aircraft Corporation Model: S-61L | S-61N | S-61NM | S-61R Product Type: Aircraft Product Subtype: Rotorcraft Affected AD: Superseded AD: Affected By: Superseded By: Service/Office: Office of Primary Responsibility: CFR Part Reference: Part 39 Comments: AIRWORTHINESS DIRECTIVES FINAL RULES: 76-03-02 CITATION: This information is not available. PAGE NUMBER: DOCKET NUMBER: Unknown AMENDMENT: 39-2507 AD NUMBER: 76-03-02 SUBJECT HEADING: Airworthiness Directives; Sikorsky Models S-61L, S-61N, S- 61NM, and S-61R Helicopters Including Military CH-3C, HH-3C, CH- 3E, and HH-3E Helicopters ACTION: SUMMARY: DATES: Effective February 17, 1976. ADDRESSES: FOR FURTHER INFORMATION CONTACT: SUPPLEMENTARY INFORMATION: REGULATORY TEXT: 76-03-02 SIKORSKY AIRCRAFT: Amendment 39-2507. Applies to S-61L, S-61N, S- 61NM, and S-61R helicopters certified in all categories including Military CH-3C, HH-3C, CH- 3E, and HH-3E helicopters using NAS 577-10 or NAS 577-10A barrel nuts for attaching the transmission main gearbox to the fuselage structure. Compliance required as indicated. To prevent fractures in the attaching nuts accomplish the following: Remove the NAS 577-10 or NAS 577-10A barrel nuts and replace with RMLH 2577-108 barrel nuts within the next 30 days after the effective date of this AD, unless already accomplished. (NOTE: Sikorsky Service Bulletin No. 61B35-36B covers this subject.) This supersedes Amendment 39-2202 (40 FR 24355), AD 75-12-13. This amendment becomes effective February 17, 1976. FOOTER:
Source: Official FAA Source ↗
Retrieved: Apr 8, 2026
Rights: U.S. Government Public Domain
This site is not affiliated with or endorsed by the FAA. Always verify with official sources.
Related Airworthiness Directives
2023-11-07
final ruleAirworthiness Directives; Various Helicopters
Unsafe Condition: unsafe condition on these products.
2022-05-10 Recurring
final ruleAirworthiness Directives; Goodrich Externally-Mounted Hoist Assemblies
Unsafe Condition: The overload clutch in the Goodrich externally-mounted hoist assemblies can fail, leading to in-flight loss of the hoist load, possibly resulting in injury to persons on the ground or in a hoisting...
2021-10-16 Recurring
final ruleAirworthiness Directives; Carson Helicopters, Inc.; Croman Corporation; Sikorsky Aircraft Corporation; and Siller Helicopters
Unsafe Condition: The left and right input freewheel unit (IFWU) assemblies on certain main gearboxes may slip or disengage, resulting in both engines overspeeding, engine shutdowns, and loss of engine power to the ...
2021-05-19
final ruleAirworthiness Directives; Sikorsky Aircraft and Sikorsky Aircraft Corporation Helicopters
Unsafe Condition: The manufacturer determined that there may be arm assemblies in service with 15,000 or more hours time-in-service (TIS), which exceeds the life limit for this component. This condition, if not addr...
