46-23-06: Surface Combustion Fuel Burning Heater
FAA order 46-23-06 is an airworthiness directive. The FAA's subject line: Surface Combustion Fuel Burning Heater. System: heating, ice protection and utility systems.
What it applies to as the FAA lists it
- Kind of product
- Aircraft
- Makes
- Noorduyn Aviation Ltd.
- Models
- Army UC-64, Army UC-64A, Army UC-64B
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 (829 characters)
46-23-06 NOORDUYN: (Was Mandatory Note 2 of AD-2-578-1.) Applies Only to Army UC-64, -64A, and -64B Airplanes Equipped With Fuel-Burning Cabin Heaters.
Required at next periodic inspection.
The surface combustion fuel burning heater must be made inoperative by disconnecting and plugging the fuel line as near the engine as practicable unless the following modifications are accomplished:
(a) At fire resistant bulkhead must be installed between the heater and the belly fuel tank. A firewall having the fire-resistant qualities specified in CAR 3.624 will be acceptable.
(b) A fuel shutoff valve, controllable from the pilots' compartment must be installed in the fuel line between the engine and the heater.
(c) Shrouds must be installed on the heater exhaust and drain lines to isolate the lines from the airframe.
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/46-23-06.json · aircraft systems.