Feathering in Nepal Plane crash

Subject : Science and technology

Section: Msc

Concept :

A preliminary report by the Aircraft Accident Investigation Commission of Nepal on the crash of a Yeti Airlines ATR 72-500 brought to light that the propellers of the plane were found in an unusual “feathered” position.

What is ‘feathering’?

Sometimes an aeroplane’s engine stops working while it’s flying.
In an aeroplane with a propeller, the pilot can change the angle of the propeller blades so they cut through the air more efficiently. This is called “feathering” the propellers.
Feathering helps the aeroplane glide farther and stay at a safe speed. When pilots have to make an emergency landing, they often use feathering to help them.
If the propellers keep spinning even when the engine is off, it can be dangerous if the aeroplane is flying low, but it can actually help restart the engine if the aeroplane is flying high.

Types of propeller engines

Fixed-pitch propeller: As the name suggests, the angle or pitch at which the propeller blades meet the airflow is fixed. The blade angle or pitch cannot be changed.
Variable-pitch propeller: Both the fixed-pitch and adjustable-pitch propeller types have their limitations. Pilots wanted different propeller pitches for takeoff, climb, cruise, etc. — a small blade pitch is ideal for takeoff, medium pitch for climb and high pitch for cruise. They also wanted propellers whose pitch could be changed from the cockpit during the flight.
Constant-speed propeller: This is a more advanced variable-pitch propeller, in which the blade pitch changes automatically to maintain a constant aircraft speed.