AD 55-11-02
Applicability
| Type | Manufacturer | Model | Details |
|---|---|---|---|
| aircraft | Piper Aircraft Inc. | PA-23 | Airworthiness Directives; Piper Model PA-23 Aircraft |
Unsafe Condition
Excessive pressures in the hydraulic system due to thermal expansion can result in failure of the hydraulic actuating cylinders.
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Required Actions
Install thermal relief valves in the landing gear retraction line, landing gear extension line, and the flap retraction line in accordance with Piper Thermal Relief Valve Kit 754 095.
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Compliance Time
by August 1, 1955
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Affected Aircraft
Piper Model PA-23 Serial Numbers 23-1 to 23-142 Inclusive, 23-144 to 23-162 Inclusive, 23-164 to 23-173 Inclusive, 23-175 to 23-177 Inclusive, 23-179 to 23-183 Inclusive, and 23-186.
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Federal Register Abstract
Thermal Relief Valves
Applicability Source Text
Show captured applicability text from the source AD
AD Final Rules - DRS_55-11-02.html Copy URL Print/Save as PDF Document Versions Feedback Details AD Number: 55-11-02 Document Type: AD Final Rules Docket Number: Unknown Subject Heading: Airworthiness Directives; Piper Model PA-23 Aircraft Subject: Thermal Relief Valves Status: Current Citation: This information is not available. Citation Publish Date: 12/04/1956 Effective Date: Make: Piper Aircraft Inc. Model: PA-23 Product Type: Aircraft Product Subtype: Small Airplane Affected AD: Superseded AD: Affected By: Superseded By: Service/Office: AIR-700: Compliance & Airworthiness Division Office of Primary Responsibility: AIR-720: Operational Safety Branch CFR Part Reference: Part 39 Comments: unable to find issue date AIRWORTHINESS DIRECTIVES FINAL RULES: 55-11-02 CITATION: This information is not available. PAGE NUMBER: DOCKET NUMBER: Unknown AMENDMENT: AD NUMBER: 55-11-02 SUBJECT HEADING: Airworthiness Directives; Piper Model PA-23 Aircraft ACTION: SUMMARY: DATES: ADDRESSES: FOR FURTHER INFORMATION CONTACT: SUPPLEMENTARY INFORMATION: REGULATORY TEXT: 55-11-02 PIPER: Applies to Model PA-23 Serial Numbers 23-1 to 23-142 Inclusive, 23- 144 to 23-162 Inclusive, 23-164 to 23-173 Inclusive, 23-175 to 23-177 Inclusive, 23-179 to 23- 183 Inclusive, and 23-186. Compliance required by August 1, 1955. In order to eliminate excessive pressures in the hydraulic system due to thermal expansion which can result in failure of the hydraulic actuating cylinders, it will be necessary to install thermal relief valves in the landing gear retraction line, landing gear extension line and the flap retraction line. These relief valves are to be installed in accordance with the sketch and instructions contained in Piper Thermal Relief Valve Kit 754 095. (Piper Service Bulletin No. 136 dated April 26, 1955, covers this same subject.) FOOTER:
Document Text
Show stored source text (verify against official source)
AD Final Rules - DRS_55-11-02.html Copy URL Print/Save as PDF Document Versions Feedback Details AD Number: 55-11-02 Document Type: AD Final Rules Docket Number: Unknown Subject Heading: Airworthiness Directives; Piper Model PA-23 Aircraft Subject: Thermal Relief Valves Status: Current Citation: This information is not available. Citation Publish Date: 12/04/1956 Effective Date: Make: Piper Aircraft Inc. Model: PA-23 Product Type: Aircraft Product Subtype: Small Airplane Affected AD: Superseded AD: Affected By: Superseded By: Service/Office: AIR-700: Compliance & Airworthiness Division Office of Primary Responsibility: AIR-720: Operational Safety Branch CFR Part Reference: Part 39 Comments: unable to find issue date AIRWORTHINESS DIRECTIVES FINAL RULES: 55-11-02 CITATION: This information is not available. PAGE NUMBER: DOCKET NUMBER: Unknown AMENDMENT: AD NUMBER: 55-11-02 SUBJECT HEADING: Airworthiness Directives; Piper Model PA-23 Aircraft ACTION: SUMMARY: DATES: ADDRESSES: FOR FURTHER INFORMATION CONTACT: SUPPLEMENTARY INFORMATION: REGULATORY TEXT: 55-11-02 PIPER: Applies to Model PA-23 Serial Numbers 23-1 to 23-142 Inclusive, 23- 144 to 23-162 Inclusive, 23-164 to 23-173 Inclusive, 23-175 to 23-177 Inclusive, 23-179 to 23- 183 Inclusive, and 23-186. Compliance required by August 1, 1955. In order to eliminate excessive pressures in the hydraulic system due to thermal expansion which can result in failure of the hydraulic actuating cylinders, it will be necessary to install thermal relief valves in the landing gear retraction line, landing gear extension line and the flap retraction line. These relief valves are to be installed in accordance with the sketch and instructions contained in Piper Thermal Relief Valve Kit 754 095. (Piper Service Bulletin No. 136 dated April 26, 1955, covers this same subject.) FOOTER:
Source: Official FAA Source ↗
Retrieved: Apr 8, 2026
Rights: U.S. Government Public Domain
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