AD 56-27-04
Applicability
| Type | Manufacturer | Model | Details |
|---|---|---|---|
| aircraft | Sierra Hotel Aero, Inc. | Navion B | Airworthiness Directives; Navion B Type Aircraft |
Unsafe Condition
Cylinder head and oil temperature values can exceed established limits due to engine cooling tests revealing overheating risks from Reading Aviation Service Inc. or Hackenberg Sales and Service downdraft cooling kit installations.
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Required Actions
Remove the Reading Aviation Service Inc. or Hackenberg Aviation Sales Service downdraft cooling kit and return to original Ryan cooling configuration, or modify the kit per Reading Aviation Service Inc. Service Bulletin No. 1 dated July 26, 1956.
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Compliance Time
not later than July 1, 1957
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Affected Aircraft
Sierra Hotel Aero, Inc. Navion B Type Aircraft equipped with Reading Aviation Service Inc. or Hackenberk Sales and Service Downdraft Cooling Kit installations.
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Federal Register Abstract
Engine Cooling Kit Removal
Applicability Source Text
Show captured applicability text from the source AD
AD Final Rules - DRS_56-27-04.html Copy URL Print/Save as PDF Document Versions Feedback Details AD Number: 56-27-04 Document Type: AD Final Rules Docket Number: Unknown Subject Heading: Airworthiness Directives; Navion B Type Aircraft Subject: Engine Cooling Kit Removal Status: Current Citation: This information is not available. Citation Publish Date: Effective Date: Make: Sierra Hotel Aero, Inc. Model: Navion B Product Type: Aircraft Product Subtype: Small Airplane Affected AD: Superseded AD: Affected By: Superseded By: Service/Office: Office of Primary Responsibility: CFR Part Reference: Part 39 Comments: AIRWORTHINESS DIRECTIVES FINAL RULES: 56-27-04 CITATION: This information is not available. PAGE NUMBER: DOCKET NUMBER: Unknown AMENDMENT: AD NUMBER: 56-27-04 SUBJECT HEADING: Airworthiness Directives; Navion B Type Aircraft ACTION: SUMMARY: DATES: ADDRESSES: FOR FURTHER INFORMATION CONTACT: SUPPLEMENTARY INFORMATION: REGULATORY TEXT: 56-27-04 NAVION: Applies to B Type Aircraft Equipped with Reading Aviation Service Inc. or Hackenberk Sales and Service Downdraft Cooling Kit Installations. Compliance required not later than July 1, 1957. Engine cooling tests conducted subsequent to the installation of these kits reveal that cylinder head and oil temperature values can exceed established limits. To prevent serious damage to the engines in these aircraft due to overheating, one of the following alternate actions is necessary. 1. Remove Reading Aviation Service Inc. or Hackenberg Aviation Sales Service downdraft cooling kit and return aircraft to the original Ryan cooling configuration, or 2. Modify the Reading or Hackenberg engine cooling kit in accordance with Reading Aviation Service Inc. Service Bulletin No. 1 dated July 26, 1956. FOOTER:
Document Text
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AD Final Rules - DRS_56-27-04.html Copy URL Print/Save as PDF Document Versions Feedback Details AD Number: 56-27-04 Document Type: AD Final Rules Docket Number: Unknown Subject Heading: Airworthiness Directives; Navion B Type Aircraft Subject: Engine Cooling Kit Removal Status: Current Citation: This information is not available. Citation Publish Date: Effective Date: Make: Sierra Hotel Aero, Inc. Model: Navion B Product Type: Aircraft Product Subtype: Small Airplane Affected AD: Superseded AD: Affected By: Superseded By: Service/Office: Office of Primary Responsibility: CFR Part Reference: Part 39 Comments: AIRWORTHINESS DIRECTIVES FINAL RULES: 56-27-04 CITATION: This information is not available. PAGE NUMBER: DOCKET NUMBER: Unknown AMENDMENT: AD NUMBER: 56-27-04 SUBJECT HEADING: Airworthiness Directives; Navion B Type Aircraft ACTION: SUMMARY: DATES: ADDRESSES: FOR FURTHER INFORMATION CONTACT: SUPPLEMENTARY INFORMATION: REGULATORY TEXT: 56-27-04 NAVION: Applies to B Type Aircraft Equipped with Reading Aviation Service Inc. or Hackenberk Sales and Service Downdraft Cooling Kit Installations. Compliance required not later than July 1, 1957. Engine cooling tests conducted subsequent to the installation of these kits reveal that cylinder head and oil temperature values can exceed established limits. To prevent serious damage to the engines in these aircraft due to overheating, one of the following alternate actions is necessary. 1. Remove Reading Aviation Service Inc. or Hackenberg Aviation Sales Service downdraft cooling kit and return aircraft to the original Ryan cooling configuration, or 2. Modify the Reading or Hackenberg engine cooling kit in accordance with Reading Aviation Service Inc. Service Bulletin No. 1 dated July 26, 1956. 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.
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