AD 48-15-03
Applicability
| Type | Manufacturer | Model | Details |
|---|---|---|---|
| aircraft | The Boeing Company | C54-DC | Airworthiness Directives; DOUGLAS C-54 and DC-4 Aircraft |
| aircraft | The Boeing Company | C54A-DC | Airworthiness Directives; DOUGLAS C-54 and DC-4 Aircraft |
| aircraft | The Boeing Company | C54B-DC | Airworthiness Directives; DOUGLAS C-54 and DC-4 Aircraft |
| aircraft | The Boeing Company | C54D-DC | Airworthiness Directives; DOUGLAS C-54 and DC-4 Aircraft |
| aircraft | The Boeing Company | C54E-DC | Airworthiness Directives; DOUGLAS C-54 and DC-4 Aircraft |
| aircraft | The Boeing Company | C54G-DC | Airworthiness Directives; DOUGLAS C-54 and DC-4 Aircraft |
| aircraft | The Boeing Company | DC-4 | Airworthiness Directives; DOUGLAS C-54 and DC-4 Aircraft |
Unsafe Condition
Service failures of hydraulic pressure regulator valves (Douglas P/N 5104005, 5231848, 5327293) could lead to loss of hydraulic pressure regulation.
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Required Actions
Modify, convert, or install specified hydraulic pressure regulator valves (Douglas P/N 5332857; Bendix P/N 407484; Air Associates P/N HC-3600; Vickers P/N AA-34551/AA-34552/AA-34585 with 'C' or later serial suffix). Install hydraulic fluid filter with Purolator core in affected regulators.
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Compliance Time
November 1, 1948
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Affected Aircraft
Douglas C-54 and DC-4 aircraft with hydraulic pressure regulator valves P/N 5104005, 5231848, or 5327293
AI-generated summary from the source AD text. Verify against the official source before acting.
Federal Register Abstract
Hydraulic Pressure Regulator Rework
Applicability Source Text
Show captured applicability text from the source AD
AD Final Rules - DRS_48-15-03.html Copy URL Print/Save as PDF Document Versions Feedback Details AD Number: 48-15-03 Document Type: AD Final Rules Docket Number: Unknown Subject Heading: Airworthiness Directives; DOUGLAS C-54 and DC-4 Aircraft Subject: Hydraulic Pressure Regulator Rework Status: Current Citation: This information is not available. Citation Publish Date: Effective Date: Make: The Boeing Company Model: C54-DC | C54A-DC | C54B-DC | C54D-DC | C54E-DC | C54G-DC | DC-4 Product Type: Aircraft Product Subtype: Large Airplane Affected AD: Superseded AD: Affected By: Superseded By: Service/Office: Office of Primary Responsibility: CFR Part Reference: Part 39 Comments: AIRWORTHINESS DIRECTIVES FINAL RULES: 48-15-03 CITATION: This information is not available. PAGE NUMBER: DOCKET NUMBER: Unknown AMENDMENT: AD NUMBER: 48-15-03 SUBJECT HEADING: Airworthiness Directives; DOUGLAS C-54 and DC-4 Aircraft ACTION: SUMMARY: DATES: ADDRESSES: FOR FURTHER INFORMATION CONTACT: SUPPLEMENTARY INFORMATION: REGULATORY TEXT: 48-15-03 DOUGLAS: Applies to C-54 and DC-4 Aircraft. Compliance required by November 1, 1948. Because of service failures of hydraulic pressure regulator valves, the following must be accomplished: 1. (a) Modify Douglas hydraulic pressure regulator valve P/N 5104005, P/N 5231848, or P/N 5327293 to the equivalent of Douglas regulator P/N 5332857, or (b) Convert Douglas hydraulic pressure regulator valve P/N 5104005, P/N 5231848, or P/N 5327293 to Douglas regulator P/N 5332857, or (c) Install Douglas hydraulic pressure regulator P/N 5332857, or (d) Install Bendix hydraulic pressure regulator P/N 407484, or (e) Install Air Associates hydraulic pressure regulator valve P/N HC-3600, or (f) Install Vickers hydraulic pressure regulator valve P/N AA-34551, P/N AA-34552, or P/N AA-34585 which must have the letter "C" or subsequent terminating the regulator serial number, i.e., "Serial No. 0000C," "Serial No. 0000D," etc. 2. Install a hydraulic fluid filter with Purolator core in regulators listed in 1, (a) through (d). (Douglas Service Bulletin DC-4 No. 22, "Rework of Hydraulic Pressure Regulator Valve" with addendum, "Optional Installation of Hydraulic Pressure Regulators" covers part 1. Douglas Service Bulletin C-54-239, "Installation of Filter in Hydraulic Regulator Operating Line," covers part 2.) FOOTER:
Document Text
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AD Final Rules - DRS_48-15-03.html Copy URL Print/Save as PDF Document Versions Feedback Details AD Number: 48-15-03 Document Type: AD Final Rules Docket Number: Unknown Subject Heading: Airworthiness Directives; DOUGLAS C-54 and DC-4 Aircraft Subject: Hydraulic Pressure Regulator Rework Status: Current Citation: This information is not available. Citation Publish Date: Effective Date: Make: The Boeing Company Model: C54-DC | C54A-DC | C54B-DC | C54D-DC | C54E-DC | C54G-DC | DC-4 Product Type: Aircraft Product Subtype: Large 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: 48-15-03 CITATION: This information is not available. PAGE NUMBER: DOCKET NUMBER: Unknown AMENDMENT: AD NUMBER: 48-15-03 SUBJECT HEADING: Airworthiness Directives; DOUGLAS C-54 and DC-4 Aircraft ACTION: SUMMARY: DATES: ADDRESSES: FOR FURTHER INFORMATION CONTACT: SUPPLEMENTARY INFORMATION: REGULATORY TEXT: 48-15-03 DOUGLAS: Applies to C-54 and DC-4 Aircraft. Compliance required by November 1, 1948. Because of service failures of hydraulic pressure regulator valves, the following must be accomplished: 1. (a) Modify Douglas hydraulic pressure regulator valve P/N 5104005, P/N 5231848, or P/N 5327293 to the equivalent of Douglas regulator P/N 5332857, or (b) Convert Douglas hydraulic pressure regulator valve P/N 5104005, P/N 5231848, or P/N 5327293 to Douglas regulator P/N 5332857, or (c) Install Douglas hydraulic pressure regulator P/N 5332857, or (d) Install Bendix hydraulic pressure regulator P/N 407484, or (e) Install Air Associates hydraulic pressure regulator valve P/N HC-3600, or (f) Install Vickers hydraulic pressure regulator valve P/N AA-34551, P/N AA-34552, or P/N AA-34585 which must have the letter "C" or subsequent terminating the regulator serial number, i.e., "Serial No. 0000C," "Serial No. 0000D," etc. 2. Install a hydraulic fluid filter with Purolator core in regulators listed in 1, (a) through (d). (Douglas Service Bulletin DC-4 No. 22, "Rework of Hydraulic Pressure Regulator Valve" with addendum, "Optional Installation of Hydraulic Pressure Regulators" covers part 1. Douglas Service Bulletin C-54-239, "Installation of Filter in Hydraulic Regulator Operating Line," covers part 2.) 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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