Drain Valve Maintenance Tips

Maintenance Tips:

Curtis Superior and SAF-AIR valves are designed for installation in a standard NPT port for NPT threaded valves or an AND-10050 style port for UNF threaded valves. Use a sealant on NPT threaded valves or a fuel resistant O-ring of the proper size for UNF threaded valves. Refer to aircraft manufacturer's torque specifications for the aircraft in which it is being used or to the torque specifications in the table below for Curtis valves.

Replace the rubber seals as per the aircraft manufacturer’s recommendations or every ten years when no guidance is given. McFarlane stocks replacement seals and seal kits for both Curtis Superior and SAF-AIR. The new Curtis valves use a O-ring type seal instead of the flat seal that was previously used. 

SAF-AIR valves are designed to be disassembled and the O-rings replaced. Over time, if the valve should start to leak, check to make sure the drain valve is tight. If drain valve is found to be tight, then check the O-rings. All O-rings used are buna "n", MS29513 style, MIL-P-5315. SAF-AIR O-ring seal kits are available for most of their valves.

Never have a hose attached in flight to the oil drain valve. Engine vibration and the additional attached mass can cause premature seal and valve wear which could result in valve failure and a loss of engine oil.