General Information

Thrust is the force that move the aircraft through the air.Thrust is generated by the propulsion system of the aircraft. There are different types of propulsion systems develop thrust in different ways, although it usually generated through some application of Newton's Third Law. Propeller is one of the propulsion system. The purpose of the propeller is to move the aircraft through the air. The propeller consist of two or more blades connected together by a hub. The hub serves to attach the blades to the engine shaft. .

The blades are made in the shape of an airfoil like wing of an aircraft. When the engine rotates the propeller blades, the blades produce lift. This lift is called thrust and moves the aircraft forward. most aircraft have propellers that pull the aircraft through the air. These are called tractor propellers. Some aircraft have propellers that push the aircraft. These are called pusher propellers.

Description

Leading Edge of the airfoil is the cutting edge that slices into the air. As the leading edge cuts the air, air flows over the blade face and the cambe side.

Blade Face is the surface of the propeller blade that corresponds to the lower surface of an airfoil or flat side, we called Blade Face.

Blade Back / Thrust Face is the curved surface of the airfoil.

Blade Shank (Root) is the section of the blade nearest the hub.

Blade Tip is the outer end of the blade fartest from the hub.

Plane of Rotation is an imaginary plane perpendicular to the shaft. It is the plane that contains the circle in which the blades rotate.

Blade Angle is formed between the face of an element and the plane of rotation. The blade angle throughout the length of the blade is not the same. The reason for placing the blade element sections at different angles is because the various sections of the blade travel at different speed. Each element must be designed as part of the blade to operate at its own best angle of attack to create thrust when revolving at its best design speed

Blade Element are the airfoil sections joined side by side to form the blade airfoil. These elements are placed at different angles in rotation of the plane of rotation.

      The reason for placing the blade element sections at different angles is because the various sections of the blade travel at different speeds. The inner part of the blade section travels slower than the outer part near the tip of the blade. If all the elements along a blade is at the same blade angle, the relative wind will not strike the elements at the same angle of attack. This is because of the different in velocity of the blade element due to distance from the center of rotation.
      The blade has a small twist (due to different angle in each section) in it for a very important reason. When the propeller is spinning round, each section of the blade travel at different speed, The twist in the peopeller blade means that each section advance forward at the same rate so stopping the propeller from bending.
      Thrust is produced by the propeller attached to the engine driveshaft. While the propeller is rotating in flight, each section of the blade has a motion that combines the forward motion of the aircraft with circular movement of the propeller. The slower the speed, the steeper the angle of attack must be to generate lift. Therefore, the shape of the propeller's airfoil (cross section) must chang from the center to the tips. The changing shape of the airfoil (cross section) across the blade results in the twisting shape of the propeller.

Relative Wind is the air that strikes and pass over the airfoil as the airfoil is driven through the air.

Angle of Attack is the angle between the chord of the element and the relative wind. The best efficiency of the propeller is obtained at an angle of attack around 2 to 4 degrees.

Blade Path is the path of the direction of the blade element moves.

Pitch refers to the distance a spiral threaded object moves forward in one revolution. As a wood screw moves forward when turned in wood, same with the propeller move forward when turn in the air.

Geometric Pitch is the theoritical distance a propeller would advance in one revolution.

Effective Pitch is the actual distance a propeller advances in one revolution in the air. The effective pitch is always shorter than geometric pitch due to the air is a fluid and always slip.

Forces and stresses acting on a propeller in flight

The forces acting on a propeller in flight are :
     1. Thrust is the air force on the propeller which is parallel to the directionof advance and induce bending stress in the propeller.
     2. Centrifugal force is caused by rotation of the propeller and tends to throw the blade out from the center.
     3. Torsion or Twisting forces in the blade itself, caused by the resultant of air forces which tend to twist the blades toward a lower blade angle.

The stress acting on a propeller in flight are :
     1. Bending stresses are induced by the trust forces. These stresses tend to bend the blade forward as the airplane is moved through the air by the propeller.
     2. Tensile stresses are caused by centrifugal force.
     3. Torsion stresses are produced in rotating propeller blades by two twisting moments. one of these stresses is caused by the air reaction on the blades and is called the aerodynamic twisting moment. The another stress is caused by centrifugal force and is called the centrifugal twisting moment.

PERFORMANCE RECOVERY WASH P&WC PT6A-27 ENGINE

NO	PROCEDURES	Penjelasan
1.	Fill the wash tank 5 litres of cleaning solution. (Mixture of Magnus 25% and water 75% by volume, drinking quality water is permissible).	Ini terpulang pada jurutera,(rujuk dulu) ade yag nak nisbah 1:3 , 1:5 , dan cuba dapatkan drinking kualiti air(air yg bertapislah).Kalau dah takde pakai je air paip biasa.
2.	Pressurise the wash tank with air or nitrogen (30-50 PSI). Connect the wash wand to pressurised tank.	Sebelum isi angin pastikan cup di tutup rapat dan secure. Isi angin dalam press tank seperti biasa.
3.	Open the cowlings, cut the locking wire and disconnect P3 air pressure line at approximately 5 o’clock position of rear fire seal mounting (view from rear). Install suitable blankings.	Hose ..ni besar dari yg lain.( macam di balut dengan kertas aluminium) lepas tu tutp dengan blank. Kalau takde blank tu , guna plastic.
4.	Position the wash wand on the compressor inlet screen.	Wash wand ni yg bentuk macam penyangkut tu.Letak di air inlet screen dan halakan ke dalam( compressure turbine)
5.	A.Open the ignition C/B in the cockpit.	RUJUK GAMBAR
5.	B. Push the cabin heating selector to the cold position.
6.	Connect the GPU supply to aircraft and carry out motoring as follow:-
	C. Idle control lever CUT OFF.
	D. Power control lever at DETENT.
	E. Prop. Control lever FEATHER.
	F. Aux fuel pump switch ON
	G. Set the starter switch to ON.	Masa ni stater / propeller mula bergerak/ pusing ..so s/by
	H. When Ng reaches 5% inject cleaning mixture/water for rinse cycle into the engine end keep on the injection.	Masa NG sampai 5% jurtera akan bagi signal/ jerit “GO” ..baru ‘supply’ air.
	- Stop motoring (Max. duration 30 second).	Dalam masa 30 saat jurutera akan ‘stop motoring’ air masih lagi di supply sehingga...
	- Cut the cleaning mixture/water injection as soon as Ng. falls to 5%.	NG drop To 5% ..jurutera kan signal/jerit stop..
	- Switch OFF the Aux. fuel pump.	Di offkan kemudian utk tujuan lubrication pada system.
7.	Remove the wash wand and disconnect it from the wash tank.	Tanggalkan wash wand dari wash tank.
8.	Allow cleaning solution to soak for 15 to 30 minutes.	Biarkan terendam 15-20 minit.
9.	Fill the separate tank with 10 litres of water. ( Drinking quality water is permissible ).	Isi semuala air jika perlu.

10.	Pressurise the tank with air or nitrogen (30 to 50 PSI). Connect the wash wand to pressurised tank.	Tambah pressure dalam tank jika perlu.
11.	Carry out raising with water two times repeating procedure 4 to 6. ( Observe the limitations of starter ).	Bila semual engine ulangan 2 x mengikut step 4-6.
12.	Removed the wash wand and blankings.	Tanggalkan wash wand dan blank
13.	Reconnect the coupling nut of P3 Air tube, torque the nut 90 to 100 lb. In and wire lock.	Pasang semula p3 line dan torque/secure dengan locking wire.
14.	Close the cowlings, reset the ignition C/B and carry out engine ground run at 80% Ng. for one minute or more to completely dry the engine and check for zero leakage at reconnected coupling nut.	Tutup semula cawling Reset cb Dan carried- out EGR at 80%