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This is a collection of operational tips I've run across
for Aeromatic propellers.
Good Overhaul Shops and Advice
There are very few folks in the world who understand Aeromatic propellers. The two I've had experience with are:
For info, try some of the type clubs of aircraft that use Aeromatics, such as Globe Swifts, Fairchild 24s, and the occasional Stinson 108.
Modern Equivalent for Hub Fluid
The Aeromatic manuals call for Aeromatic 5M fluid. Since this Aeromatic company no longer exists you cannot get this fluid. Kent Tarver says that the modern equivalent is SAE 70 to 90 gear oil. Specific brands include Chevron RPM Universal Gear Lubricant 80W-90, or Shell SPIRAX S Gear Oil 75S-90
Aeromatics just leak. This is the verdict from everybody I've ever talked to. You can try to replace the seals by completely disassembling the hub, but it will probably start to leak again within a few hours of service.
Service Bulletin for Wood Rot
Aeromatic propeller blades are made out of wood cores covered with a plastic coating. Wood propeller blades are quite strong and reliable, as wood does not fatigue and tends not to have the vibration resonance problems that metal propellers can have.
Wood will, however, rot if subjected to too much or too little moisture. On the Aeromatic it is also possible for the attachment lag screws that hold the wooden blade cores to the metal blade butt flanges to corrode. Because the Aeromatic wooden core is covered in plastic it can be difficult to inspect the condition of the material. Severely neglected propellers have been known to depart the airplane while in operation. Tarver issued a service bulletin in 2000 with inspection procedures.
Prop Nut Torque
On a Cessna Airmaster, you get good at installing and removing the propeller since that's the only way to get the propeller off. The manuals are unclear on the proper torque for the prop nut. The correct torque seems to be in the range of 400 ft/lbs. I use a 3 foot bar, which then requires 133 lbs of force.
Field Service Manual
See also the Aeromatic Field Service Manual.