AD 51-15-02
Applicability
| Type | Manufacturer | Model | Details |
|---|---|---|---|
| engine | Wytwornia Sprzetu Komunikacyjnego | 6A4-165-B3 | FRANKLIN Model 6A4-165-B3 Engines |
Unsafe Condition
Cracks in the crankcase webbing near the main journal area and at the main bearing stud hole, which could lead to crankcase fracture and engine failure.
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Required Actions
Inspect the crankcase webbing near the main journal area for cracks. Replace crankcases with fractures or advanced cracks with P/N 18925 assembly. Inspect at 250-hour intervals if no cracks found, or 50-hour intervals if surface cracks or cracks near main bearing stud hole are detected.
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Compliance Time
by July 15, 1951. Effective on and after this date, inspections required for engines with 500 hours of operation since new or 250 hours since last overhaul.
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Affected Aircraft
Franklin Model 6A4-165-B3 Engines serial numbers 33046 and below with original crankcase assembly P/N 18553 (left half No. 18305; right half No. 18306).
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Federal Register Abstract
Crankcase
Applicability Source Text
Show captured applicability text from the source AD
AD Final Rules - DRS_51-15-02.html Copy URL Print/Save as PDF Document Versions Feedback Details AD Number: 51-15-02 Document Type: AD Final Rules Docket Number: Unknown Subject Heading: FRANKLIN Model 6A4-165-B3 Engines Subject: Crankcase Status: Current Citation: This information is not available. Citation Publish Date: Effective Date: Make: Wytwornia Sprzetu Komunikacyjnego Model: 6A4-165-B3 Product Type: Engine Product Subtype: Affected AD: Superseded AD: Affected By: Superseded By: Service/Office: Office of Primary Responsibility: CFR Part Reference: Part 39 Comments: AIRWORTHINESS DIRECTIVES FINAL RULES: 51-15-02 CITATION: This information is not available. PAGE NUMBER: DOCKET NUMBER: Unknown AMENDMENT: AD NUMBER: 51-15-02 SUBJECT HEADING: FRANKLIN Model 6A4-165-B3 Engines ACTION: SUMMARY: DATES: ADDRESSES: FOR FURTHER INFORMATION CONTACT: SUPPLEMENTARY INFORMATION: REGULATORY TEXT: 51-15-02 FRANKLIN: Applies to All Franklin 6A4-165-B3 Engines Serially Numbered 33046 and Below Incorporating Original Crankcase (Left Half No. 18305; Right Half No. 18306). These Two Parts Form Crankcase Assembly, P/N 18553. The Number of Each Crankcase Half is Located on Each Casting Below the Number 1 and 6 Cylinder Location. To be accomplished by July 15, 1951. Effective on and after this date, all applicable crankcases with 500 hours of operation since new or 250 hours since last overhaul should be inspected as follows: Remove crankcase cover and visually inspect the webbing near the main journal area for cracks. (1) Crankcases found to be free of cracks should be inspected at 250-hour intervals thereafter. In the event that the conditions described in (2) and (3) are detected, the provisions of (2) and (3) will apply. (2) Crankcases found with (a) surface indications, hairline cracks, or small wall cracks and (b) cracks starting at main bearing stud hole on the opposite side from main bearing support, may be operated further at the option of the owner. Such crankcases should be inspected at 50-hour intervals thereafter to determine progress of cracks. (3) Crankcases found fractured or with cracks that have progressed to the extent that they enter the main bearing supports (usually from back near (a) main bearing stud hole and (b) drilled oil hole) indicate that a complete break soon will occur. Such crankcases should be replaced with the reinforced crankcase assembly, P/N 18925, at which time no further inspection is required. Crankcase assembly P/N 18925 may be identified by casting No. 18905 appearing below No. 1 cylinder location and casting No. 18906 appearing below No. 6 cylinder location. (Franklin Service News No. 10 also covers this subject.) FOOTER:
Document Text
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AD Final Rules - DRS_51-15-02.html Copy URL Print/Save as PDF Document Versions Feedback Details AD Number: 51-15-02 Document Type: AD Final Rules Docket Number: Unknown Subject Heading: FRANKLIN Model 6A4-165-B3 Engines Subject: Crankcase Status: Current Citation: This information is not available. Citation Publish Date: Effective Date: Make: Wytwornia Sprzetu Komunikacyjnego Model: 6A4-165-B3 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: AIRWORTHINESS DIRECTIVES FINAL RULES: 51-15-02 CITATION: This information is not available. PAGE NUMBER: DOCKET NUMBER: Unknown AMENDMENT: AD NUMBER: 51-15-02 SUBJECT HEADING: FRANKLIN Model 6A4-165-B3 Engines ACTION: SUMMARY: DATES: ADDRESSES: FOR FURTHER INFORMATION CONTACT: SUPPLEMENTARY INFORMATION: REGULATORY TEXT: 51-15-02 FRANKLIN: Applies to All Franklin 6A4-165-B3 Engines Serially Numbered 33046 and Below Incorporating Original Crankcase (Left Half No. 18305; Right Half No. 18306). These Two Parts Form Crankcase Assembly, P/N 18553. The Number of Each Crankcase Half is Located on Each Casting Below the Number 1 and 6 Cylinder Location. To be accomplished by July 15, 1951. Effective on and after this date, all applicable crankcases with 500 hours of operation since new or 250 hours since last overhaul should be inspected as follows: Remove crankcase cover and visually inspect the webbing near the main journal area for cracks. (1) Crankcases found to be free of cracks should be inspected at 250-hour intervals thereafter. In the event that the conditions described in (2) and (3) are detected, the provisions of (2) and (3) will apply. (2) Crankcases found with (a) surface indications, hairline cracks, or small wall cracks and (b) cracks starting at main bearing stud hole on the opposite side from main bearing support, may be operated further at the option of the owner. Such crankcases should be inspected at 50-hour intervals thereafter to determine progress of cracks. (3) Crankcases found fractured or with cracks that have progressed to the extent that they enter the main bearing supports (usually from back near (a) main bearing stud hole and (b) drilled oil hole) indicate that a complete break soon will occur. Such crankcases should be replaced with the reinforced crankcase assembly, P/N 18925, at which time no further inspection is required. Crankcase assembly P/N 18925 may be identified by casting No. 18905 appearing below No. 1 cylinder location and casting No. 18906 appearing below No. 6 cylinder location. (Franklin Service News No. 10 also covers this subject.) FOOTER:
Source: Official FAA Source ↗
Retrieved: Apr 8, 2026
Rights: U.S. Government Public Domain
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