Originally Posted by
Three Lima Charlie
Yes, it is possible to put the propeller into "feather" pitch with the prop (RPM) lever on the console. But the feather button in most aircraft also triggers several other actions to isolate the engine at the firewall by closing valves to shut off fuel, oil, hydraulic fluid flow, disconnect electrical connections and arm the fire extinguisher bottle (if equipped). Some propellers, once feathered, a pin drops into place and will require maintenance to reset the pin and manually move the blade back to a normal pitch position.
MarkerInbound obviously paid attention in class and has it exactly correct. The feather button does only one thing and that is to close a relay that starts the the feather pump motor. It takes 300 psi to feather on this engine / propeller combination and 600 psi to unfeather. The feather button has no other functions, none! And, retarding the prop control lever fully will only allow the propeller governor to go to the high pitch stops and low RPM not feather as in a light twin. Fuel shut-off, hydraulic and oil isolation is accomplished by an engine fluid shut-off handle or fire handle. Some of these handles will arm the fire extinguisher bottles, depending on the aircraft type, others will not. Additionally, you can't be serious about a pin dropping in place to prevent unfeathering. There are no such pins in the dome of any of the round engine types I have flown. The only thing that comes close to this comment and had to be reset on the ground is a cabin compressor which did have this feature, if disconnected in flight.