AD 48-12-02
Applicability
| Type | Manufacturer | Model | Details |
|---|---|---|---|
| aircraft | The Boeing Company | C54-DC | Airworthiness Directives; DOUGLAS C54-DC and DC-4 |
| aircraft | The Boeing Company | C54A-DC | Airworthiness Directives; DOUGLAS C54-DC and DC-4 |
| aircraft | The Boeing Company | C54B-DC | Airworthiness Directives; DOUGLAS C54-DC and DC-4 |
| aircraft | The Boeing Company | C54D-DC | Airworthiness Directives; DOUGLAS C54-DC and DC-4 |
| aircraft | The Boeing Company | C54E-DC | Airworthiness Directives; DOUGLAS C54-DC and DC-4 |
| aircraft | The Boeing Company | C54G-DC | Airworthiness Directives; DOUGLAS C54-DC and DC-4 |
| aircraft | The Boeing Company | DC-4 | Airworthiness Directives; DOUGLAS C54-DC and DC-4 |
Unsafe Condition
Heater fires in the nose and cabin heater installations pose a fire hazard due to lack of isolation between the heater compartment and adjacent fuselage spaces, non-hermetic heater control components, and inadequate protection of fuel line fittings.
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Required Actions
Install a steel firewall at Station 260 from ceiling level to top of bulkhead, replace wood panels under heaters with metal panels, install airtight steel containers for heater control components, replace fuel supply pumps with a single electric-driven pump attached to No. 2 main fuel tank, provide shrouds around heater fuel line fittings, and install a fire detector and extinguisher system for nose and cabin heaters.
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Compliance Time
not later than the date established in accordance with the provisions of Special Civil Air Regulation Serial Number SR-329, or any subsequent regulation affecting this compliance date
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Affected Aircraft
The Boeing Company C54-DC and DC-4 models with serial numbers 42904 Through 42943, 42948 Through 42952, 42982 Through 42996, 43065 Through 43068, 43071, 43072, 43093, 43094, and 43102.
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Source: Official FAA Source ↗
Retrieved: Apr 8, 2026
Rights: U.S. Government Public Domain
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