48-15-03: Hydraulic Pressure Regulator Rework
FAA order 48-15-03 is an airworthiness directive. The FAA's subject line: Hydraulic Pressure Regulator Rework. It names Douglas C-54: about 7 aircraft on the U.S. register today, though an order usually covers particular versions or serial numbers rather than every one. System: heating, ice protection and utility systems.
What it applies to as the FAA lists it
- Kind of product
- Aircraft
- Makes
- The Boeing Company
- Models
- C54-DC, C54A-DC, C54B-DC, C54D-DC, C54E-DC, C54G-DC, DC-4
- On this site
- Douglas C-54 7 registered
Dates and paperwork
- Docket
- Unknown
- Status
- Current
- The FAA's document
- Read the order on the FAA's site
The order itself the regulatory text, as published
Show the full text (1,394 characters)
48-15-03 DOUGLAS: Applies to C-54 and DC-4 Aircraft. \n\n\tCompliance required by November 1, 1948. \n\n\tBecause of service failures of hydraulic pressure regulator valves, the following must be accomplished: \n\n\t1.\t(a)\tModify 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 \n\n\t\t(b)\tConvert Douglas hydraulic pressure regulator valve P/N 5104005, P/N 5231848, or P/N 5327293 to Douglas regulator P/N 5332857, or \n\n\t\t(c)\tInstall Douglas hydraulic pressure regulator P/N 5332857, or \n\n\t\t(d)\tInstall Bendix hydraulic pressure regulator P/N 407484, or \n\n\t\t(e)\tInstall Air Associates hydraulic pressure regulator valve P/N HC-3600, or \n\n\t\t(f)\tInstall 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. \n\n\t2.\tInstall a hydraulic fluid filter with Purolator core in regulators listed in 1, (a) through (d). \n\n\t(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.)
Related safety bulletins advice on the same designs, not orders
2014-11-24NM-15-03 · Flight Controls
Source: FAA Dynamic Regulatory System, airworthiness directives. The FAA's document is the authority; the register counts are this site's, from the FAA register of November 6, 2026. Connections as data: /graph/directive/48-15-03.json · aircraft systems.