AD 51-04-02
Applicability
| Type | Manufacturer | Model | Details |
|---|---|---|---|
| engine | Warner Engine Company, LLC | Scarab Jr. Series 40 | WARNER Model All Engines Except Those With the Letter "A" |
| engine | Warner Engine Company, LLC | Scarab Jr. Series 50 | WARNER Model All Engines Except Those With the Letter "A" |
| engine | Warner Engine Company, LLC | Scarab Series 28 | WARNER Model All Engines Except Those With the Letter "A" |
| engine | Warner Engine Company, LLC | Scarab Series 29 | WARNER Model All Engines Except Those With the Letter "A" |
| engine | Warner Engine Company, LLC | Scarab Series 30 | WARNER Model All Engines Except Those With the Letter "A" |
| engine | Warner Engine Company, LLC | Scarab Series 40 | WARNER Model All Engines Except Those With the Letter "A" |
| engine | Warner Engine Company, LLC | Scarab Series 50 | WARNER Model All Engines Except Those With the Letter "A" |
| engine | Warner Engine Company, LLC | Super Scarab Series 165 | WARNER Model All Engines Except Those With the Letter "A" |
| engine | Warner Engine Company, LLC | Super Scarab Series 165-B | WARNER Model All Engines Except Those With the Letter "A" |
| engine | Warner Engine Company, LLC | Super Scarab Series 165-D | WARNER Model All Engines Except Those With the Letter "A" |
| engine | Warner Engine Company, LLC | Super Scarab Series 185 | WARNER Model All Engines Except Those With the Letter "A" |
| engine | Warner Engine Company, LLC | Super Scarab Series 185J | WARNER Model All Engines Except Those With the Letter "A" |
| engine | Warner Engine Company, LLC | Super Scarab Series 185K | WARNER Model All Engines Except Those With the Letter "A" |
| engine | Warner Engine Company, LLC | Super Scarab Series 40 | WARNER Model All Engines Except Those With the Letter "A" |
| engine | Warner Engine Company, LLC | Super Scarab Series 50 | WARNER Model All Engines Except Those With the Letter "A" |
| engine | Warner Engine Company, LLC | Super Scarab Series 50A | WARNER Model All Engines Except Those With the Letter "A" |
Unsafe Condition
Failure of the 5/16-inch cylinder holddown studs P/N S506, which can result from stretching due to loose nuts leading to fatigue failure.
AI-generated summary from the source AD text. Verify against the official source before acting.
Required Actions
Inspect cylinder holddown nuts for torque between 180 and 200 inch-pounds, replace broken studs for the affected cylinder, and replace all studs if nuts are loose. Alternatively, replace 5/16-inch studs S506 and nuts N-511 with 3/8-inch stud S-911 and nut N-910, install an 'O' type ring gasket, and stamp 'A' on the engine nameplate.
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Compliance Time
As soon as possible but not later than April 1, 1951 and at each 100 hours of operation thereafter.
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Affected Aircraft
Warner Engine Company, LLC engines: Scarab Jr. Series 40, Scarab Jr. Series 50, Scarab Series 28, Scarab Series 29, Scarab Series 30, and others except those with the letter 'A' stamped after the serial number on the engine nameplate.
AI-generated summary from the source AD text. Verify against the official source before acting.
Federal Register Abstract
Cylinder Holddown Studs
Applicability Source Text
Show captured applicability text from the source AD
AD Final Rules - DRS_51-04-02.html Copy URL Print/Save as PDF Document Versions Feedback Details AD Number: 51-04-02 Document Type: AD Final Rules Docket Number: Unknown Subject Heading: WARNER Model All Engines Except Those With the Letter "A" Subject: Cylinder Holddown Studs Status: Current Citation: This information is not available. Citation Publish Date: Effective Date: Make: Warner Engine Company, LLC Model: Scarab Jr. Series 40 | Scarab Jr. Series 50 | Scarab Series 28 | Scarab Series 29 | Scarab Series 30...Show more Product Type: Engine Product Subtype: 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: 51-04-02 CITATION: This information is not available. PAGE NUMBER: DOCKET NUMBER: Unknown AMENDMENT: AD NUMBER: 51-04-02 SUBJECT HEADING: WARNER Model All Engines Except Those With the Letter "A" ACTION: SUMMARY: DATES: ADDRESSES: FOR FURTHER INFORMATION CONTACT: SUPPLEMENTARY INFORMATION: REGULATORY TEXT: 51-04-02 WARNER: Applies to All Engines Except Those With the Letter "A" Stamped After the Serial Number on the Engine Nameplate. The Letter "A" Indicates That the Modifications Hereinafter Discussed Have Already Been Accomplished. Compliance required as indicated. As a precautionary measure to preclude serious flight hazards resulting from failure of the 5/16-inch cylinder holddown studs P/N S506, the following inspections or replacements should be accomplished. A. Compliance required as soon as possible but not later than April 1, 1951 and at each 100 hours of operation thereafter. 1. Check the cylinder holddown nuts to determine that they are tightened to a torque of 180 inch- pounds desired to a 200 inch-pounds maximum. (a) If one or more of the studs is found to be broken, replace all of the studs for the particular cylinder. (b) Loose cylinder holddown nuts are a good indication that the stud may have stretched to the extent that fatigue failure may soon result. If one or more of the nuts is found loose, it is recommended that all of the studs in the cylinder be replaced. (c) When installing a cylinder with oil on the stud threads, tighten nuts to 200 inch-pounds desired to 225 inch-pounds maximum. (Warner Service Letter No. A-15 discusses procedures for inspecting and replacing 5/16-inch studs and nuts.) B. Compliance not required, but will eliminate foregoing mandatory inspections. 1. Replace cylinder stud P/N S506 and nut N-511 with 3/8-inch stud S-911 and nut N-910. 2. Replace gasket between cylinder barrel and crankcase with an "O" type ring. 3. Stamp letter "A" after serial number on engine nameplate when this modification has been completed. (Warner Service Letter No. A-17 explains the details connected with the replacement of these parts.) The Warner Aircraft Co., P. O. Box 229, Niles, Mich., which purchased the assets of the Warner Division of the Clinton Machine Co., Detroit, Mich., have a large supply of replacement part stocks that will be held in their inventory for an indefinite period. Warner Service Letter No. A-17 should be consulted before ordering these replacement parts. If either Letter A-17 or Letter A-15 is not available, copies may be obtained from the Warner Aircraft Co., Box 229, Niles, Mich. FOOTER:
Document Text
Show stored source text (verify against official source)
AD Final Rules - DRS_51-04-02.html Copy URL Print/Save as PDF Document Versions Feedback Details AD Number: 51-04-02 Document Type: AD Final Rules Docket Number: Unknown Subject Heading: WARNER Model All Engines Except Those With the Letter "A" Subject: Cylinder Holddown Studs Status: Current Citation: This information is not available. Citation Publish Date: Effective Date: Make: Warner Engine Company, LLC Model: Scarab Jr. Series 40 | Scarab Jr. Series 50 | Scarab Series 28 | Scarab Series 29 | Scarab Series 30...Show more Product Type: Engine Product Subtype: 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: 51-04-02 CITATION: This information is not available. PAGE NUMBER: DOCKET NUMBER: Unknown AMENDMENT: AD NUMBER: 51-04-02 SUBJECT HEADING: WARNER Model All Engines Except Those With the Letter "A" ACTION: SUMMARY: DATES: ADDRESSES: FOR FURTHER INFORMATION CONTACT: SUPPLEMENTARY INFORMATION: REGULATORY TEXT: 51-04-02 WARNER: Applies to All Engines Except Those With the Letter "A" Stamped After the Serial Number on the Engine Nameplate. The Letter "A" Indicates That the Modifications Hereinafter Discussed Have Already Been Accomplished. Compliance required as indicated. As a precautionary measure to preclude serious flight hazards resulting from failure of the 5/16-inch cylinder holddown studs P/N S506, the following inspections or replacements should be accomplished. A. Compliance required as soon as possible but not later than April 1, 1951 and at each 100 hours of operation thereafter. 1. Check the cylinder holddown nuts to determine that they are tightened to a torque of 180 inch- pounds desired to a 200 inch-pounds maximum. (a) If one or more of the studs is found to be broken, replace all of the studs for the particular cylinder. (b) Loose cylinder holddown nuts are a good indication that the stud may have stretched to the extent that fatigue failure may soon result. If one or more of the nuts is found loose, it is recommended that all of the studs in the cylinder be replaced. (c) When installing a cylinder with oil on the stud threads, tighten nuts to 200 inch-pounds desired to 225 inch-pounds maximum. (Warner Service Letter No. A-15 discusses procedures for inspecting and replacing 5/16-inch studs and nuts.) B. Compliance not required, but will eliminate foregoing mandatory inspections. 1. Replace cylinder stud P/N S506 and nut N-511 with 3/8-inch stud S-911 and nut N-910. 2. Replace gasket between cylinder barrel and crankcase with an "O" type ring. 3. Stamp letter "A" after serial number on engine nameplate when this modification has been completed. (Warner Service Letter No. A-17 explains the details connected with the replacement of these parts.) The Warner Aircraft Co., P. O. Box 229, Niles, Mich., which purchased the assets of the Warner Division of the Clinton Machine Co., Detroit, Mich., have a large supply of replacement part stocks that will be held in their inventory for an indefinite period. Warner Service Letter No. A-17 should be consulted before ordering these replacement parts. If either Letter A-17 or Letter A-15 is not available, copies may be obtained from the Warner Aircraft Co., Box 229, Niles, Mich. FOOTER:
Source: Official FAA Source ↗
Retrieved: Apr 8, 2026
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