Iainhol From , joined Dec 1969, posts, RR: Reply 1, posted (12 years 1 month 4 days 20 hours ago) and read 5780 times:
You feather a prop after an engine failure, to decrease drag. What happens is you basically increase the angle of the blade (pull the prop pitch back), and the prop will not spin, and create less drag.
I am sure some one else can go into more detail I have only done this once!
As Iain has said it is a system designed to reduce drag by taking the prop pitch almost perpendicular to the airflow, which in most cases will stop the rotation (as in the pic).
On most prop aircraft this is a very important part of engine failure survivability, and feathering is conducted when the crew is sure the engine is dead (feathering the wrong prop has been performed with fatal consequences).
The system is normally run with either the pitch control/condition lever or a feather button, and depending on the design of the prop hub it normally dumps all oil pressure allowing a feathering spring to move the blades to feather.
On a free turbine the prop can be feathered with the engine still running, and you will often see this when a Dash 8 or Saab 340 type starts up or shuts down. With the engine running the blades 'growl' and appear to run very slowly....this is feather! No forward thrust is being developed, so it is good for running the engine in confined spaces.
Finally a lot of advanced prop aircraft have a system called autofeather that detects a loss of power to the prop and feathers it immediately. Some aircraft, like the B200 Kingair, also apply rudder to assist the crew in the emergency situation.
Cosync From Mexico, joined Nov 2001, 556 posts, RR: 0 Reply 5, posted (12 years 1 month 4 days 2 hours ago) and read 5686 times:
oi iainhol i know what u mean heheh
when the proppeler is feathered it means that u push the prop control all the way back so that the propeller doesnt spin and it is cutting through the air. if u have an engine failure u fweather it to let the propeller swipe throught the air with less drag and less stress put on the proppeler. i am not a pilot just a guy who reads alot of books about planes hehehe