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.