AD 75-12-01
Applicability
| Type | Manufacturer | Model | Details |
|---|---|---|---|
| aircraft | Sikorsky Aircraft Corporation | S-61L | Airworthiness Directives; Sikorsky Models S-61L, S-61N, S-61R and S-61NM Helicopters Including Military Type 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-61R and S-61NM Helicopters Including Military Type 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-61R and S-61NM Helicopters Including Military Type 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-61R and S-61NM Helicopters Including Military Type CH-3C, HH-3C, CH-3E, and HH-3E Helicopters |
Unsafe Condition
Free counterweights or loose material in the main rotor blade spar cavity may cause blade failure.
AI-generated summary from the source AD text. Verify against the official source before acting.
Required Actions
Inspect each main rotor blade before first flight of each day and upon noting unusual one-per-rev vibration using Sikorsky Service Bulletin S61B15-18B or FAA-approved revisions. Remove blades from service if any sound indicates free counterweights or loose material and notify Sikorsky Product Support.
AI-generated summary from the source AD text. Verify against the official source before acting.
Compliance Time
Prior to the first flight of each day and before further flight if unusual vibration is noted.
AI-generated summary from the source AD text. Verify against the official source before acting.
Affected Aircraft
Sikorsky Models S-61L, S-61N, S-61R, S-61NM helicopters including Military types CH-3C, HH-3C, CH-3E, HH-3E equipped with main rotor blades S6115-20501 (up to -9), S6115-20601 (up to -044), S6117-20101 (up to -053), or S6188-15001 (up to -044) series.
AI-generated summary from the source AD text. Verify against the official source before acting.
Federal Register Abstract
Main Rotor Blades
Applicability Source Text
Show captured applicability text from the source AD
AD Final Rules - DRS_75-12-01.html Copy URL Print/Save as PDF Document Versions Feedback Details AD Number: 75-12-01 Document Type: AD Final Rules Docket Number: Unknown Subject Heading: Airworthiness Directives; Sikorsky Models S-61L, S-61N, S-61R and S-61NM Helicopters Including Milit...Show more Subject: Main Rotor Blades Status: Current Citation: This information is not available. Citation Publish Date: Effective Date: 06/12/1975 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: 75-12-01 CITATION: This information is not available. PAGE NUMBER: DOCKET NUMBER: Unknown AMENDMENT: 39-2221 AD NUMBER: 75-12-01 SUBJECT HEADING: Airworthiness Directives; Sikorsky Models S-61L, S-61N, S-61R and S-61NM Helicopters Including Military Type CH-3C, HH-3C, CH-3E, and HH-3E Helicopters ACTION: SUMMARY: DATES: Effective June 12, 1975. ADDRESSES: FOR FURTHER INFORMATION CONTACT: SUPPLEMENTARY INFORMATION: REGULATORY TEXT: 75-12-01 SIKORSKY AIRCRAFT: Amendment 39-2221. Applies to S-61L, S-61N, S- 61R and S-61NM helicopters certificated in all categories including Military type CH-3C, HH- 3C, CH-3E, and HH-3E helicopters equipped with the following main rotor blades: (1) S6115-20501 series, prior to and including S6115-20501-9 main rotor blade assemblies. (2) S6115-20601 series, prior to and including S6115-20601-044 main rotor blade assemblies. (3) S6117-20101 series, prior to and including S6117-20101-053 main rotor blade assemblies. (4) S6188-15001 series, prior to and including S6188-15001-044 main rotor blade assemblies. Compliance required as indicated. (a) Prior to the first flight of each day, inspect each main rotor blade in accordance with Section 2, paragraph C of Sikorsky Service Bulletin No. S61B15-18B or later FAA-approved revisions for possible free counterweights or loose material in the blade spar cavity. If any sound is evident, remove the blade from service immediately and notify Sikorsky Aircraft Product Support Department. (b) If any unusual one-per-rev vibration is noted, inspect each main rotor blade prior to further flight for a possible free counter-weight or loose material in the spar cavity in accordance with Section 2, paragraph C of Sikorsky Service Bulletin No. 61B15-18B or later FAA-approved revisions. If any sound is evident, remove the blade from service immediately and notify Sikorsky Aircraft Product Support Department. (c) Upon request of the operator, equivalent methods of compliance with the inspection requirements of this AD may be approved by the Chief, Engineering and Manufacturing Branch, New England Region, if the request contains substantiating data to justify that equivalent method for that operator. This supersedes Amendment 39-1992 (39 F.R. 37356), AD 74-22-02 and Amendment 39-2031 (39 F.R. 41739), AD 74-25-07. This amendment becomes effective June 12, 1975. FOOTER:
Document Text
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AD Final Rules - DRS_75-12-01.html Copy URL Print/Save as PDF Document Versions Feedback Details AD Number: 75-12-01 Document Type: AD Final Rules Docket Number: Unknown Subject Heading: Airworthiness Directives; Sikorsky Models S-61L, S-61N, S-61R and S-61NM Helicopters Including Milit...Show more Subject: Main Rotor Blades Status: Current Citation: This information is not available. Citation Publish Date: Effective Date: 06/12/1975 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: 75-12-01 CITATION: This information is not available. PAGE NUMBER: DOCKET NUMBER: Unknown AMENDMENT: 39-2221 AD NUMBER: 75-12-01 SUBJECT HEADING: Airworthiness Directives; Sikorsky Models S-61L, S-61N, S-61R and S-61NM Helicopters Including Military Type CH-3C, HH-3C, CH-3E, and HH-3E Helicopters ACTION: SUMMARY: DATES: Effective June 12, 1975. ADDRESSES: FOR FURTHER INFORMATION CONTACT: SUPPLEMENTARY INFORMATION: REGULATORY TEXT: 75-12-01 SIKORSKY AIRCRAFT: Amendment 39-2221. Applies to S-61L, S-61N, S- 61R and S-61NM helicopters certificated in all categories including Military type CH-3C, HH- 3C, CH-3E, and HH-3E helicopters equipped with the following main rotor blades: (1) S6115-20501 series, prior to and including S6115-20501-9 main rotor blade assemblies. (2) S6115-20601 series, prior to and including S6115-20601-044 main rotor blade assemblies. (3) S6117-20101 series, prior to and including S6117-20101-053 main rotor blade assemblies. (4) S6188-15001 series, prior to and including S6188-15001-044 main rotor blade assemblies. Compliance required as indicated. (a) Prior to the first flight of each day, inspect each main rotor blade in accordance with Section 2, paragraph C of Sikorsky Service Bulletin No. S61B15-18B or later FAA-approved revisions for possible free counterweights or loose material in the blade spar cavity. If any sound is evident, remove the blade from service immediately and notify Sikorsky Aircraft Product Support Department. (b) If any unusual one-per-rev vibration is noted, inspect each main rotor blade prior to further flight for a possible free counter-weight or loose material in the spar cavity in accordance with Section 2, paragraph C of Sikorsky Service Bulletin No. 61B15-18B or later FAA-approved revisions. If any sound is evident, remove the blade from service immediately and notify Sikorsky Aircraft Product Support Department. (c) Upon request of the operator, equivalent methods of compliance with the inspection requirements of this AD may be approved by the Chief, Engineering and Manufacturing Branch, New England Region, if the request contains substantiating data to justify that equivalent method for that operator. This supersedes Amendment 39-1992 (39 F.R. 37356), AD 74-22-02 and Amendment 39-2031 (39 F.R. 41739), AD 74-25-07. This amendment becomes effective June 12, 1975. FOOTER:
Source: Official FAA Source ↗
Retrieved: Apr 8, 2026
Rights: U.S. Government Public Domain
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