AD 70-12-04
Applicability
| Type | Manufacturer | Model | Details |
|---|---|---|---|
| aircraft | Sikorsky Aircraft Corporation | S-55 | Airworthiness Directives; Sikorsky Models S-55, S-55B, S-55C, and S-62A Type Helicopters |
| aircraft | Sikorsky Aircraft Corporation | S-55B | Airworthiness Directives; Sikorsky Models S-55, S-55B, S-55C, and S-62A Type Helicopters |
| aircraft | Sikorsky Aircraft Corporation | S-55C | Airworthiness Directives; Sikorsky Models S-55, S-55B, S-55C, and S-62A Type Helicopters |
| aircraft | Sikorsky Aircraft Corporation | S62A | Airworthiness Directives; Sikorsky Models S-55, S-55B, S-55C, and S-62A Type Helicopters |
Unsafe Condition
Failure of the main rotor shaft due to fatigue cracks originating from surface conditions.
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Required Actions
Inspect main rotor shaft P/N S14-35-4308-1, -2, -3, or -4 for cracks and surface conditions using Sikorsky Service Bulletin 55B35-3, 62B35-10 (dated 3 April 1970) or equivalent. Retire and replace shafts with cracks or unreworkable conditions before further flight. Rework shafts with reworkable conditions per the same service bulletins, ensuring replacement shafts are inspected if removed from the main gear box.
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Compliance Time
within the next 15 hours in service after the effective date of this AD
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Affected Aircraft
Sikorsky Models S-55, S-55B, S-55C, and S-62A Type Helicopters certificated in all categories.
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Federal Register Abstract
Main Rotor Shaft Cracks
Applicability Source Text
Show captured applicability text from the source AD
AD Final Rules - DRS_70-12-04.html Copy URL Print/Save as PDF Document Versions Feedback Details AD Number: 70-12-04 Document Type: AD Final Rules Docket Number: Unknown Subject Heading: Airworthiness Directives; Sikorsky Models S-55, S-55B, S-55C, and S-62A Type Helicopters Subject: Main Rotor Shaft Cracks Status: Current Citation: This information is not available. Citation Publish Date: Effective Date: 06/17/1970 Make: Sikorsky Aircraft Corporation Model: S-55 | S-55B | S-55C | S62A Product Type: Aircraft Product Subtype: Rotorcraft Affected AD: Superseded AD: Affected By: Superseded By: Service/Office: Office of Primary Responsibility: CFR Part Reference: Part 39 Comments: AIRWORTHINESS DIRECTIVES FINAL RULES: 70-12-04 CITATION: This information is not available. PAGE NUMBER: DOCKET NUMBER: Unknown AMENDMENT: 39-997 AD NUMBER: 70-12-04 SUBJECT HEADING: Airworthiness Directives; Sikorsky Models S-55, S-55B, S-55C, and S-62A Type Helicopters ACTION: SUMMARY: DATES: Effective June 17, 1970. ADDRESSES: FOR FURTHER INFORMATION CONTACT: SUPPLEMENTARY INFORMATION: REGULATORY TEXT: 70-12-04 SIKORSKY ROTORCRAFT: Amdt. 39-997. Applies to S-55, S-55B, S-55C, and S-62A type helicopters certificated in all categories. Compliance required within the next 15 hours in service after the effective date of this AD, unless already accomplished. To prevent failure of the main rotor shaft due to fatigue cracks originating from surface conditions, accomplish the following: (a) Inspect main rotor shaft P/N S14-35-4308-1, -2, -3 or -4, for cracks and surface conditions in accordance with applicable Sikorsky Service Bulletin No. 55B35-3 or 62B35-10 dated 3 April 1970, or later FAA approved revision, or an equivalent inspection procedure approved by the Chief, Engineering and Manufacturing Branch, FAA Eastern Region. (b) Main rotor shafts exhibiting crack indications, or unreworkable surface conditions shall be retired from service prior to further flight and replaced with a shaft which has been inspected in accordance with paragraph (a). (c) Main rotor shafts found with reworkable surface conditions may be reworked in accordance with applicable Sikorsky Service Bulletin No. 55B35-3 or 62B35-10 dated 3 April 1970, or later FAA approved revision, or an equivalent rework procedure approved by the Chief, Engineering and Manufacturing Branch, FAA Eastern Region. Should the extent of rework necessitate removal of the shaft from the main gear box, then the replacement shaft must have been inspected in accordance with paragraph (a). (d) Upon request of the operator, an FAA maintenance inspector, subject to prior approval of the Chief, Engineering and Manufacturing Branch, FAA Eastern Region may adjust the compliance time specified in this AD if the request contains substantiating data to justify the increase for that operator. This amendment is effective June 17, 1970. FOOTER:
Document Text
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AD Final Rules - DRS_70-12-04.html Copy URL Print/Save as PDF Document Versions Feedback Details AD Number: 70-12-04 Document Type: AD Final Rules Docket Number: Unknown Subject Heading: Airworthiness Directives; Sikorsky Models S-55, S-55B, S-55C, and S-62A Type Helicopters Subject: Main Rotor Shaft Cracks Status: Current Citation: This information is not available. Citation Publish Date: Effective Date: 06/17/1970 Make: Sikorsky Aircraft Corporation Model: S-55 | S-55B | S-55C | S62A 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: 70-12-04 CITATION: This information is not available. PAGE NUMBER: DOCKET NUMBER: Unknown AMENDMENT: 39-997 AD NUMBER: 70-12-04 SUBJECT HEADING: Airworthiness Directives; Sikorsky Models S-55, S-55B, S-55C, and S-62A Type Helicopters ACTION: SUMMARY: DATES: Effective June 17, 1970. ADDRESSES: FOR FURTHER INFORMATION CONTACT: SUPPLEMENTARY INFORMATION: REGULATORY TEXT: 70-12-04 SIKORSKY ROTORCRAFT: Amdt. 39-997. Applies to S-55, S-55B, S-55C, and S-62A type helicopters certificated in all categories. Compliance required within the next 15 hours in service after the effective date of this AD, unless already accomplished. To prevent failure of the main rotor shaft due to fatigue cracks originating from surface conditions, accomplish the following: (a) Inspect main rotor shaft P/N S14-35-4308-1, -2, -3 or -4, for cracks and surface conditions in accordance with applicable Sikorsky Service Bulletin No. 55B35-3 or 62B35-10 dated 3 April 1970, or later FAA approved revision, or an equivalent inspection procedure approved by the Chief, Engineering and Manufacturing Branch, FAA Eastern Region. (b) Main rotor shafts exhibiting crack indications, or unreworkable surface conditions shall be retired from service prior to further flight and replaced with a shaft which has been inspected in accordance with paragraph (a). (c) Main rotor shafts found with reworkable surface conditions may be reworked in accordance with applicable Sikorsky Service Bulletin No. 55B35-3 or 62B35-10 dated 3 April 1970, or later FAA approved revision, or an equivalent rework procedure approved by the Chief, Engineering and Manufacturing Branch, FAA Eastern Region. Should the extent of rework necessitate removal of the shaft from the main gear box, then the replacement shaft must have been inspected in accordance with paragraph (a). (d) Upon request of the operator, an FAA maintenance inspector, subject to prior approval of the Chief, Engineering and Manufacturing Branch, FAA Eastern Region may adjust the compliance time specified in this AD if the request contains substantiating data to justify the increase for that operator. This amendment is effective June 17, 1970. FOOTER:
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Retrieved: Apr 8, 2026
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