AD 74-16-05
Applicability
| Type | Manufacturer | Model | Details |
|---|---|---|---|
| aircraft | Erickson Air-Crane | S-64A | Airworthiness Directives; Sikorsky Models S-64A, S-64E, and S-56 Helicopters |
| aircraft | Erickson Air-Crane | S-64E | Airworthiness Directives; Sikorsky Models S-64A, S-64E, and S-56 Helicopters |
Unsafe Condition
Fatigue failures of the main rotor head spindle lock nut, part numbers S1510-23031-0 and S1510-23031-1.
AI-generated summary from the source AD text. Verify against the official source before acting.
Required Actions
Replace the main rotor head spindle lock nut with a serviceable part of the same part number before specified time-in-service hours. Repeat replacement at intervals not exceeding 750 hours for P/N S1510-23031-0 or 10,500 hours for P/N S1510-23031-1.
AI-generated summary from the source AD text. Verify against the official source before acting.
Compliance Time
Before the accumulation of 750 hours time in service (for P/N S1510-23031-0) or 10,500 hours time in-service (for P/N S1510-23031-1), or within the next 25 hours time in service after the effective date of this AD, whichever occurs later.
AI-generated summary from the source AD text. Verify against the official source before acting.
Affected Aircraft
Sikorsky Models S-64A, S-64E, and S-56 helicopters certificated in all categories.
AI-generated summary from the source AD text. Verify against the official source before acting.
Federal Register Abstract
Main Rotor Head Spindle Lock Nut
Applicability Source Text
Show captured applicability text from the source AD
AD Final Rules - DRS_74-16-05.html Copy URL Print/Save as PDF Document Versions Feedback Details AD Number: 74-16-05 Document Type: AD Final Rules Docket Number: Unknown Subject Heading: Airworthiness Directives; Sikorsky Models S-64A, S-64E, and S-56 Helicopters Subject: Main Rotor Head Spindle Lock Nut Status: Current Citation: This information is not available. Citation Publish Date: Effective Date: 12/12/1974 Make: Erickson Air-Crane Model: S-64A | S-64E Product Type: Aircraft Product Subtype: Rotorcraft Affected AD: Superseded AD: Affected By: Superseded By: Service/Office: Office of Primary Responsibility: CFR Part Reference: Part 39 Comments: AIRWORTHINESS DIRECTIVES FINAL RULES: 74-16-05 CITATION: This information is not available. PAGE NUMBER: DOCKET NUMBER: Unknown AMENDMENT: 39-2033 AD NUMBER: 74-16-05 SUBJECT HEADING: Airworthiness Directives; Sikorsky Models S-64A, S-64E, and S-56 Helicopters ACTION: SUMMARY: DATES: Effective December 12, 1974. ADDRESSES: FOR FURTHER INFORMATION CONTACT: SUPPLEMENTARY INFORMATION: REGULATORY TEXT: 74-16-05 SIKORSKY AIRCRAFT: Amendment 39-1910 is amended by Amendment 39-2033. Applies to S-64A, S-64E, and S-56 helicopters certificated in all categories. Compliance required as indicated. To prevent fatigue failures of the main rotor head spindle lock nut, accomplish the following: (a) Before the accumulation of 750 hours time in service on a main rotor head spindle lock nut, P/N S1510-23031-0, or within the next 25 hours time in service after the effective date of this AD, whichever occurs later, replace the affected lock nut with a serviceable part of the same part number and thereafter repeat replacement at intervals not to exceed 750 hours time in service. (b) Before the accumulation of 10,500 hours time in service on a main rotor head spindle lock nut, P/N S1510-23031-1, or within the next 25 hours time in service after the effective date of this AD, whichever occurs later, replace the affected lock nut with a serviceable part of the same part number and thereafter repeat replacement at intervals not to exceed 10,500 hours time in service. Amendment 39-1910 became effective August 15, 1974. This amendment 39-2033 becomes effective December 12, 1974. FOOTER:
Document Text
Show stored source text (verify against official source)
AD Final Rules - DRS_74-16-05.html Copy URL Print/Save as PDF Document Versions Feedback Details AD Number: 74-16-05 Document Type: AD Final Rules Docket Number: Unknown Subject Heading: Airworthiness Directives; Sikorsky Models S-64A, S-64E, and S-56 Helicopters Subject: Main Rotor Head Spindle Lock Nut Status: Current Citation: This information is not available. Citation Publish Date: Effective Date: 12/12/1974 Make: Erickson Air-Crane Model: S-64A | S-64E 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: 74-16-05 CITATION: This information is not available. PAGE NUMBER: DOCKET NUMBER: Unknown AMENDMENT: 39-2033 AD NUMBER: 74-16-05 SUBJECT HEADING: Airworthiness Directives; Sikorsky Models S-64A, S-64E, and S-56 Helicopters ACTION: SUMMARY: DATES: Effective December 12, 1974. ADDRESSES: FOR FURTHER INFORMATION CONTACT: SUPPLEMENTARY INFORMATION: REGULATORY TEXT: 74-16-05 SIKORSKY AIRCRAFT: Amendment 39-1910 is amended by Amendment 39-2033. Applies to S-64A, S-64E, and S-56 helicopters certificated in all categories. Compliance required as indicated. To prevent fatigue failures of the main rotor head spindle lock nut, accomplish the following: (a) Before the accumulation of 750 hours time in service on a main rotor head spindle lock nut, P/N S1510-23031-0, or within the next 25 hours time in service after the effective date of this AD, whichever occurs later, replace the affected lock nut with a serviceable part of the same part number and thereafter repeat replacement at intervals not to exceed 750 hours time in service. (b) Before the accumulation of 10,500 hours time in service on a main rotor head spindle lock nut, P/N S1510-23031-1, or within the next 25 hours time in service after the effective date of this AD, whichever occurs later, replace the affected lock nut with a serviceable part of the same part number and thereafter repeat replacement at intervals not to exceed 10,500 hours time in service. Amendment 39-1910 became effective August 15, 1974. This amendment 39-2033 becomes effective December 12, 1974. 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.