AD 57-12-03
Applicability
| Type | Manufacturer | Model | Details |
|---|---|---|---|
| aircraft | Scotts-Bell 47 Inc | 47J | Airworthiness Directives; Bell Model 47J Helicopters |
Unsafe Condition
Failure of the engine sprag spindle P/N 47-612-167-1 due to overtorquing of the AN 320-10 nut.
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Required Actions
Remove spindle and links, install AN 6-17 bolt with AN 960-616L washer, drill No. 52 hole in AN 320-10 nut for safety wire, torque nut to 150 inch-pounds, install AN 960-616L washer and AN 310-6 nut with cotter key, and reconnect links with original hardware.
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Compliance Time
prior to July 1, 1957
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Affected Aircraft
Bell Model 47J Helicopters with serial numbers 1420 Through 1426, 1429 Through 1433, 1435 Through 1439, and 1441, 1559, 1562, 1574.
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Federal Register Abstract
Engine Sprag Spindle
Applicability Source Text
Show captured applicability text from the source AD
AD Final Rules - DRS_57-12-03.html Copy URL Print/Save as PDF Document Versions Feedback Details AD Number: 57-12-03 Document Type: AD Final Rules Docket Number: Unknown Subject Heading: Airworthiness Directives; Bell Model 47J Helicopters Subject: Engine Sprag Spindle Status: Current Citation: This information is not available. Citation Publish Date: Effective Date: Make: Scotts-Bell 47 Inc Model: 47J Product Type: Aircraft Product Subtype: Rotorcraft Affected AD: Superseded AD: Affected By: Superseded By: Service/Office: Office of Primary Responsibility: CFR Part Reference: Part 39 Comments: Updated RGL applicability to match AD applicability; CAR C-11-185 AIRWORTHINESS DIRECTIVES FINAL RULES: 57-12-03 CITATION: This information is not available. PAGE NUMBER: DOCKET NUMBER: Unknown AMENDMENT: AD NUMBER: 57-12-03 SUBJECT HEADING: Airworthiness Directives; Bell Model 47J Helicopters ACTION: SUMMARY: DATES: ADDRESSES: FOR FURTHER INFORMATION CONTACT: SUPPLEMENTARY INFORMATION: REGULATORY TEXT: 57-12-03 BELL: Applies to Model 47J Helicopters Serial Numbers 1420 Through 1426, 1429 Through 1433, 1435 Through 1439, and 1441, 1559, 1562, 1574. Compliance required prior to July 1, 1957. In order to preclude the failure of the engine sprag spindle P/N 47-612-167-1, due to overtorquing of the AN 320-10 nut, the following modification must be accomplished. 1. Remove spindle after first removing the 47-612-166 links from the spindle and 47-612-158 brace assemblies. 2. Install one AN 6-17 bolt with one AN 960-616L washer under the head in the spindle. 3. Reinstall the previously removed links on the spindle. Drill a No. 52 (.062 dia.) hole in one castellation of the AN 320-10 nut for safety wire. Reinstall an AN 960-1016 washer and AN 320-10 nut. After positioning links, torque AN 320-10 nut to 150 inch-pounds. (NOTE: One AN 364-1018 nut may be substituted for the drilled AN 320-10 nut.) 4. Install one AN 960-616L washer and one AN 310-6 nut on end of AN 6-17 bolt. Torque to 160-190 inch-pounds and install one AN 381-3-12 cotter key. 5. Replace spindle. Resafety attach bolts and safety AN 320-10 nut (if used) to the spindle attach bolts. 6. Connect the links, using previously removed hardware. (Bell Mandatory Service Bulletin No. 120 dated March 29, 1957, covers this same subject.) FOOTER:
Document Text
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AD Final Rules - DRS_57-12-03.html Copy URL Print/Save as PDF Document Versions Feedback Details AD Number: 57-12-03 Document Type: AD Final Rules Docket Number: Unknown Subject Heading: Airworthiness Directives; Bell Model 47J Helicopters Subject: Engine Sprag Spindle Status: Current Citation: This information is not available. Citation Publish Date: Effective Date: Make: Scotts-Bell 47 Inc Model: 47J 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: Updated RGL applicability to match AD applicability; CAR C-11-185 AIRWORTHINESS DIRECTIVES FINAL RULES: 57-12-03 CITATION: This information is not available. PAGE NUMBER: DOCKET NUMBER: Unknown AMENDMENT: AD NUMBER: 57-12-03 SUBJECT HEADING: Airworthiness Directives; Bell Model 47J Helicopters ACTION: SUMMARY: DATES: ADDRESSES: FOR FURTHER INFORMATION CONTACT: SUPPLEMENTARY INFORMATION: REGULATORY TEXT: 57-12-03 BELL: Applies to Model 47J Helicopters Serial Numbers 1420 Through 1426, 1429 Through 1433, 1435 Through 1439, and 1441, 1559, 1562, 1574. Compliance required prior to July 1, 1957. In order to preclude the failure of the engine sprag spindle P/N 47-612-167-1, due to overtorquing of the AN 320-10 nut, the following modification must be accomplished. 1. Remove spindle after first removing the 47-612-166 links from the spindle and 47-612-158 brace assemblies. 2. Install one AN 6-17 bolt with one AN 960-616L washer under the head in the spindle. 3. Reinstall the previously removed links on the spindle. Drill a No. 52 (.062 dia.) hole in one castellation of the AN 320-10 nut for safety wire. Reinstall an AN 960-1016 washer and AN 320-10 nut. After positioning links, torque AN 320-10 nut to 150 inch-pounds. (NOTE: One AN 364-1018 nut may be substituted for the drilled AN 320-10 nut.) 4. Install one AN 960-616L washer and one AN 310-6 nut on end of AN 6-17 bolt. Torque to 160-190 inch-pounds and install one AN 381-3-12 cotter key. 5. Replace spindle. Resafety attach bolts and safety AN 320-10 nut (if used) to the spindle attach bolts. 6. Connect the links, using previously removed hardware. (Bell Mandatory Service Bulletin No. 120 dated March 29, 1957, covers this same subject.) FOOTER:
Source: Official FAA Source ↗
Retrieved: Apr 8, 2026
Rights: U.S. Government Public Domain
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