AVIA-1052 Complete PDF

AVIA-1052 Please let Matt C know if there are errors or improvements needed. Thanks 1  AVIA-1052 Please let Matt C know if there are errors or improvements needed. Thanks 2 Previously On AVIA-1...

AVIA-1052 Please let Matt C know if there are errors or improvements needed. Thanks 1  AVIA-1052 Please let Matt C know if there are errors or improvements needed. Thanks 2 Previously On AVIA-1052  Well there is no “previously”, this is our first class together.  Now this is first class Please let Matt C know if there are errors or improvements needed. Thanks 3 Today On AVIA-1052  We are going to talk about…  You guessed it, Propellers  Some general prop stuff  Aircraft Propeller Theory  Basic Propeller Controls Please let Matt C know if there are errors or improvements needed. Thanks 4 Where are we?  Powerplant (Vol. 2) 7-2 to 7-6   Start at General   Stop at  Propeller Location  FAA-H-8083-30A, Aviation Maintenance Technician Handbook-General  FAA-H-8083-31A, Aviation Maintenance Technician Handbook-Airframe Volume 1  FAA-H-8083-31A, Aviation Maintenance Technician Handbook-Airframe Volume 2  FAA-H-8083-32A, Aviation Maintenance Technician Handbook-Powerplant Volume 1  FAA-H-8083-32A, Aviation Maintenance Technician Handbook-Powerplant Volume 2 Please let Matt C know if there are errors or improvements needed. Thanks 5  AVIA-1052 Please let Matt C know if there are errors or improvements needed. Thanks 6  Powerplant 7-2 Propellers  the unit that must absorb the power output of the engine  Propeller development  the propeller has passed through many stages of development  propeller development has encouraged many changes as propulsion systems have evolved  the first propellers were fabric- covered sticks  Designed to force air in a rearward direction Please let Matt C know if there are errors or improvements needed. Thanks 7  Powerplant 7-2 Propellers propellers started as simple two-bladed wood propellers  have advanced to the complex propulsion systems of turboprop aircraft that involve more than just the propeller  more complex propellers  a variable-pitch, constant-speed feathering and reversing propeller system  allows the engine rpm to be varied only slightly during different flight conditions  increases flying efficiency Please let Matt C know if there are errors or improvements needed. Thanks 8  Powerplant 7-2 Propellers  constant-speed systems  a basic constant-speed system consists of:  a flyweight-equipped governor unit that controls the pitch angle of the blades so that the engine speed remains constant Please let Matt C know if there are errors or improvements needed. Thanks 9  Powerplant 7-2 Propellers  a flyweight-equipped governor unit  that controls the pitch angle of the blades so that the engine speed remains constant  can be regulated by controls in the cockpit so that any desired blade angle setting, and engine operating speed can be obtained at  takeoff  low-pitch  high-rpm setting  flight  higher pitch  lower rpm setting Please let Matt C know if there are errors or improvements needed. Thanks 10  Powerplant 7-2 Propellers  This figure shows normal propeller movement with the positions of  low pitch  high pitch  Feather-used if the engine quits to reduce drag  zero pitch into negative pitch-reverse pitch Please let Matt C know if there are errors or improvements needed. Thanks 11  Powerplant 7-2 Common Propeller Types  Propellers Please let Matt C know if there are errors or improvements needed. Thanks 12  Powerplant 7-2 Propellers  most propellers are two-bladed  great increases in power output have resulted in the development of  four-bladed propellers  six-bladed propellers of large diameters  all propeller-driven aircraft are limited by the revolutions per minute (rpm) at which propellers can be turned Please let Matt C know if there are errors or improvements needed. Thanks 13  Powerplant 7-2 Propellers  forces acting on the propeller as it turns  centrifugal force  tends to pull the blades out of the hub at high rpm  blade weight is very important to the design of a propeller Please let Matt C know if there are errors or improvements needed. Thanks 14  Powerplant 7-2 Propellers  excessive blade tip speed  rotating the propeller too fast may result in  poor blade efficiency  fluttering  vibration Please let Matt C know if there are errors or improvements needed. Thanks 15  Powerplant 7-2 Propellers  since the propeller speed is limited, the aircraft speed of a propeller driven aircraft is also limited approximately 400 miles per hour (mph) (644 kilometers per hour)  as aircraft speeds increased, turbofan engines were used for higher speed aircraft Please let Matt C know if there are errors or improvements needed. Thanks 16  Powerplant 7-2 Propellers  propeller-driven aircraft have several advantages  takeoff and landing can be  shorter  less expensive to maintain  new blade materials and manufacturing techniques have increased the efficiency of propellers  widely used for applications in  turboprops  reciprocating engine installations  many smaller aircraft will continue to use propellers well into the future Please let Matt C know if there are errors or improvements needed. Thanks 17  Powerplant 7-2 Propellers  propeller systems  many different types of propeller systems have been developed for  specific aircraft installation  speed  type of operation Please let Matt C know if there are errors or improvements needed. Thanks 18  Powerplant 7-2 Propellers  diagrams  basic nomenclature of the parts of a simple fixed-pitch, two-bladed wood propeller  aerodynamic cross-section of a blade (next slide)  includes terminology to describe certain areas shown Please let Matt C know if there are errors or improvements needed. Thanks 19  Powerplant 7-2 Propellers  aerodynamic cross-section of a blade Please let Matt C know if there are errors or improvements needed. Thanks 20  AVIA-1052 Please let Matt C know if there are errors or improvements needed. Thanks 21  Powerplant 7-2 Basic Propeller Principles  the aircraft propeller consists of:  two or more blades  each blade is essentially a rotating wing  produce forces that create thrust to pull or push the airplane through the air  the power needed to rotate the propeller blades is furnished by the engine  a central hub to which the blades are attached Please let Matt C know if there are errors or improvements needed. Thanks 22  Powerplant 7-3 Basic Propeller Principles  mounted on a shaft  low-horsepower engines which may be an extension of the  crankshaft  high-horsepower engines  mounted on a propeller shaft that is geared to the engine crankshaft  the engine rotates the airfoils of the blades through the air at high speeds  the propeller transforms the rotary power of the engine into thrust Please let Matt C know if there are errors or improvements needed. Thanks 23  Powerplant 7-3 Propeller Aerodynamic Process  an airplane moving through the air creates a drag force  opposing its forward motion  there must be a force applied to it that is equal to the drag but acting forward  if an airplane is to fly on a level path this force is called thrust  the work done by thrust is equal to the thrust times the distance it moves the airplane  work = thrust × distance  the power expended by thrust is equal to the thrust times the velocity at which it moves the airplane  power = thrust × velocity Please let Matt C know if there are errors or improvements needed. Thanks 24  Powerplant 7-3 Propeller Aerodynamic Process  the power expended by the thrust is termed thrust horsepower if the power is measured in horsepower units  the engine supplies brake horsepower through a rotating shaft  the propeller converts it into thrust horsepower  some power is wasted in this conversion  the propeller must be designed to keep this waste as small as possible for maximum efficiency  (image to the right is for a boat prop) Please let Matt C know if there are errors or improvements needed. Thanks 25  Powerplant 7-3 Propeller Aerodynamic Process  propeller efficiency is the ratio of thrust horsepower to brake horsepower since the efficiency of any machine is the ratio of the useful power output to the power input the usual symbol for propeller efficiency is the Greek letter η (eta)  propeller efficiency varies from 50-87% depending on how much the propeller slips Please let Matt C know if there are errors or improvements needed. Thanks 26  Powerplant 7-3 Propeller Aerodynamic Process  pitch is not the same as blade angle  because pitch is largely determined by blade angle  the two terms are often used interchangeably  an increase or decrease in one is usually associated with an increase or decrease in the other  blade angle  the angle between the face or chord/ chord line of a blade section and the plane in which the propeller rotates  usually measured in degrees Please let Matt C know if there are errors or improvements needed. Thanks 27  Powerplant 7-3 Propeller Aerodynamic Process  geometric pitch  is the distance a propeller should advance in one revolution with no slippage  usually expressed in pitch inches  calculated by using the following formula:  GP = 2 × π R × tangent of blade angle at 75% station  R = Radius at the 75% blade station  π = 3.14  based on no slippage Please let Matt C know if there are errors or improvements needed. Thanks 28  Powerplant 7-3 Propeller Aerodynamic Process  effective pitch is the distance it advances   recognizes propeller slippage in the air  propeller slip is the difference between the geometric pitch of the propeller and its effective pitch  geometric pitch – effective pitch = slip Please let Matt C know if there are errors or improvements needed. Thanks 29  Powerplant 7-3 Propeller Aerodynamic Process  the chord line of the propeller blade is determined in about the same manner as the chord line of an airfoil  a propeller blade can be considered as being composed of an infinite number of thin blade elements  each of which is a miniature airfoil section whose chord is the width of the propeller blade at that section  the chord line is often drawn along the face of the propeller blade because most propellers have a flat blade face Please let Matt C know if there are errors or improvements needed. Thanks 30  Powerplant 7-3 Propeller Aerodynamic Process  the typical propeller blade can be described as a twisted airfoil of irregular planform  a blade can be divided into segments that are located by station numbers in inches from the center of the blade hub  for purposes of analysis Please let Matt C know if there are errors or improvements needed. Thanks 31  Powerplant 7-4 Propeller Aerodynamic Process  the cross-sections of each 6-inch blade segment are shown as airfoils on the right side Please let Matt C know if there are errors or improvements needed. Thanks 32  Powerplant 7-4 Propeller Aerodynamic Process  also identified are:  blade shank  thick, rounded portion of the propeller blade  near the hub  designed to give strength to the blade  blade butt  also called the blade base or root  the end of the blade that fits in the propeller hub  blade tip  part of the propeller blade farthest from the hub  generally defined as the last 6 inches of the blade Please let Matt C know if there are errors or improvements needed. Thanks 33  Powerplant 7-4 Propeller Aerodynamic Process  this section or blade element is an airfoil comparable to a cross-section of an aircraft wing  blade back  cambered or curved side of the blade  like the upper surface of an aircraft wing  blade face  flat side of the propeller blade  chord line  an imaginary line drawn through the blade from the leading edge to the trailing edge  leading edge  thick edge of the blade that meets the air as the propeller rotates Please let Matt C know if there are errors or improvements needed. Thanks 34  Powerplant 7-4 Propeller Aerodynamic Process  the principal forces acting on a rotating propeller  centrifugal force  a physical force  tends to throw the rotating propeller blades away from the hub  the most dominant force on the propeller Please let Matt C know if there are errors or improvements needed. Thanks 35  Powerplant 7-4 Propeller Aerodynamic Process  torque bending  tends to bend the propeller blades in the direction opposite that of rotation  in the form of air resistance Please let Matt C know if there are errors or improvements needed. Thanks 36  Powerplant 7-4 Propeller Aerodynamic Process  thrust bending  loads that tends to bend propeller blades forward as the aircraft is pulled through the air  at least two of these forces acting on the propeller's blades are used to move the blades  on a controllable pitch propeller  centrifugal twisting  aerodynamic twisting Please let Matt C know if there are errors or improvements needed. Thanks 37  Powerplant 7-4 Propeller Aerodynamic Process  aerodynamic twisting  tends to turn the blades to a high blade angle  used to move the blades into high pitch Please let Matt C know if there are errors or improvements needed. Thanks 38  Powerplant 7-4 Propeller Aerodynamic Process  a rotating propeller is acted upon by:  centrifugal twisting  greater than the aerodynamic twisting force  tends to force the blades toward a low blade angle  sometimes used to move the blades to the low pitch position Please let Matt C know if there are errors or improvements needed. Thanks 39  Powerplant 7-4 Propeller Aerodynamic Process  a propeller must be capable of withstanding severe stresses  greater near the hub  caused by centrifugal force and thrust  increase in proportion to the rpm  the blade face is also subjected to tension from:  the centrifugal force  the bending  nicks or scratches on the blade may cause very serious consequences  these could lead to:  cracks  failure of the blade Please let Matt C know if there are errors or improvements needed. Thanks 40  Powerplant 7-4 Propeller Aerodynamic Process  a propeller must also be rigid enough to prevent fluttering  a type of vibration  the ends of the blade twist back and forth at high frequency around an axis perpendicular to the engine crankshaft  the constant vibration tends to weaken the blade and eventually causes failure  accompanied by a distinctive noise  often mistaken for exhaust noise Please let Matt C know if there are errors or improvements needed. Thanks 41  Powerplant 7-4 Aerodynamic Factors  consider first its motion  to understand the action of a propeller  which is both rotational and forward  a section of a propeller blade moves downward and forward Please let Matt C know if there are errors or improvements needed. Thanks 42  Powerplant 7-4 Aerodynamic Factors  the result is the same as if the blade were stationary and the air coming at it from a direction opposite its path  as far as the forces are concerned, the angle at which this air (relative wind) strikes the propeller blade is called angle of attack(AOA)  the air deflection produced by this angle causes the dynamic pressure at the engine side of the propeller blade to be greater than atmospheric pressure, therefore creating thrust Please let Matt C know if there are errors or improvements needed. Thanks 43  Powerplant 7-4 Aerodynamic Factors  the shape of the blade also creates thrust  because it is shaped like a wing, as the air flows past the propeller, the pressure on one side is lower than the pressure on the other side  this difference in pressure produces a reaction force in the direction of the lesser pressure  Example: the area above a wing has less pressure, the force (lift) is upward  the area of decreased pressure is in front of a propeller which is mounted in a vertical instead of a horizontal position  the force (thrust) is in a forward direction  thrust is the result of the propeller shape and the AOA of the blade aerodynamically Please let Matt C know if there are errors or improvements needed. Thanks 44  Powerplant 7-4 Aerodynamic Factors  another way to consider thrust is in terms of the mass of air handled  thrust = the mass of air handled x the slipstream velocity - the velocity of the airplane  in these terms, the power expended in producing thrust depends on the mass of air moved per second Please let Matt C know if there are errors or improvements needed. Thanks 45  Powerplant 7-4 Aerodynamic Factors  the amount of air displaced (moved) depends on the blade angle  for any single revolution of the propeller which determines the quantity or amount of mass of air the propeller moves, the blade angle is an excellent means of adjusting the load on the propeller to control the engine rpm  if the blade angle is increased, more load is placed on the engine tending to slow it down unless more power is applied Please let Matt C know if there are errors or improvements needed. Thanks 46  Powerplant 7-4 Aerodynamic Factors  thrust constitutes approximately 80% of the torque  total horsepower absorbed by the propeller balances the horsepower delivered by the engine for any speed of rotation  the other 20% is lost in friction and slippage Please let Matt C know if there are errors or improvements needed. Thanks 47  Powerplant 7-4 Aerodynamic Factors  as an airfoil is moved through the air, it produces two forces:  lift and drag  increasing propeller blade angle:  increases the AOA  produces more lift and drag  increases the horsepower required to turn the propeller at a given rpm  slows the propeller down (since the engine is still producing the same horsepower) Please let Matt C know if there are errors or improvements needed. Thanks 48  Powerplant 7-4 Aerodynamic Factors  decreasing propeller blade angle:  speeds the propeller up  the engine rpm can be controlled by increasing or decreasing the blade angle  lift versus drag curves drawn for:  propellers  wings Please let Matt C know if there are errors or improvements needed. Thanks 49  Powerplant 7-4 Aerodynamic Factors  indicate that the most efficient AOA is a small one varying from 2° to 4° positive  the actual blade angle necessary to maintain this small AOA varies with the forward speed of the airplane  due to a change in the relative wind direction which varies with aircraft speed Please let Matt C know if there are errors or improvements needed. Thanks 50  Powerplant 7-4 Aerodynamic Factors  the blade angle  an excellent method of adjusting the AOA of the propeller  the blade angle must be adjusted to provide the most efficient AOA at all engine and airplane speeds on constant-speed propellers  fixed-pitch and ground-adjustable propellers are designed: for best efficiency at:  One rotation speed  One forward speed Please let Matt C know if there are errors or improvements needed. Thanks 51  Powerplant 7-4 Aerodynamic Factors  to fit a given airplane and engine combination, a propeller may be used that provides the maximum propeller efficiency for: takeoff climb cruising high speeds  any change in these conditions results in lowering the efficiency of both the propeller and the engine Please let Matt C know if there are errors or improvements needed. Thanks 52  Powerplant 7-4 Aerodynamic Factors  A constant-speed propeller keeps the blade angle adjusted for maximum efficiency for most conditions encountered in flight  during takeoff, when maximum power and thrust are required:  the constant-speed propeller is at a low propeller blade angle or pitch  the low blade angle keeps the AOA small and efficient with respect to the relative wind  it allows the propeller to handle a smaller mass of air per revolution Please let Matt C know if there are errors or improvements needed. Thanks 53  Powerplant 7-4 Aerodynamic Factors  this light load allows the engine to turn at high rpm and to convert the maximum amount of fuel into heat energy  the high rpm also creates maximum thrust  the engine rpm is high  the slipstream velocity (air coming off the propeller) is high  the thrust is maximum with the low airplane speed Please let Matt C know if there are errors or improvements needed. Thanks 54  Powerplant 7-6 Aerodynamic Factors  after liftoff, as the speed of the airplane increases  the constant-speed propeller changes to a higher angle (or pitch)  the higher blade angle keeps the AOA small and efficient with respect to the relative wind  the higher blade angle increases the mass of air handled per revolution  this decreases the engine rpm, reducing fuel consumption and engine wear, and keeps thrust at a maximum Please let Matt C know if there are errors or improvements needed. Thanks 55  Powerplant 7-6 Aerodynamic Factors  for climb after takeoff  the power output of the engine is reduced to climb power by decreasing the manifold pressure and increasing the blade angle to lower the rpm  the torque (horsepower absorbed by the propeller) is reduced to match the reduced power of the engine  the AOA is kept small by the increase in blade angle  the greater mass of air handled per second is more than offset by the lower slipstream velocity and the increase in airspeed Please let Matt C know if there are errors or improvements needed. Thanks 56  Powerplant 7-6 Aerodynamic Factors  at cruising altitude, when the airplane is in level flight and less power is required than is used in takeoff or climb  engine power is reduced by lowering the manifold pressure and increasing the blade angle to decrease the rpm  this reduces torque to match the reduced engine power  it is more than offset by a decrease in slipstream velocity and an increase in airspeed  the AOA is still small because the blade angle has been increased with an increase in airspeed Please let Matt C know if there are errors or improvements needed. Thanks 57  Powerplant 7-6 Aerodynamic Factors  pitch distribution is the twist in the blade from the shank to the blade tip, due to the variation in speeds that each section of the blade is traveling  the tip of the blade is traveling much faster than the inner portion of the blade Please let Matt C know if there are errors or improvements needed. Thanks 58  AVIA-1052 Please let Matt C know if there are errors or improvements needed. Thanks 59 Propeller Controls and Instruments  https://youtu.be/0bP2MH3LqvI  The Propeller Explained (24.04)  https://www.youtube.com/watch?v=GNsnXjxopJM  ConstantSpeedPropPart1 (14:23) Landed valve=pilot valve=spool valve  https://youtu.be/-KyxxrEJBH0  HOW PROPELLERS ARE MADE: Hartzell Propeller (8:42)  https://youtu.be/HHXlhJlPqKg  She is a Builder! Wood Worker! Prop Maker! Machinist! (36:40)  https://www.youtube.com/c/CulverProps Please let Matt C know if there are errors or improvements needed. Thanks 60  Powerplant 7-6 Propeller Controls and Instruments  fixed pitch propellers:  have no controls  require no adjustments in flight  constant-speed propellers:  have a propeller control in the center pedestal between the throttle and the mixture control (typically a blue knob)  the two positions for the control are:  increase rpm  (full forward)  decrease rpm  (pulled aft) Please let Matt C know if there are errors or improvements needed. Thanks 61  Powerplant 7-6 Propeller Controls Please let Matt C know if there are errors or improvements needed. Thanks 62  Powerplant 7-6 Propeller Controls and Instruments  Controls are directly connected to the propeller governor and adjusts the tension on the governor speeder spring by moving the control  can be used to feather the propeller in some aircraft by moving the control to the full decrease rpm position  controls rotations per minute (rpm)  the two main instruments used are:  the engine tachometer  the manifold pressure gauge  adjusted by the throttle Please let Matt C know if there are errors or improvements needed. Thanks 63  Powerplant 7-6 Speed Sensing  tachometer generator  measures the rotational rate of a shaft using an internally generated electrical signal  reference signal or voltage is generated by rotating the generator's internal mechanism  generated alternating current (AC) is then read by tachometer circuitry and displayed Please let Matt C know if there are errors or improvements needed. Thanks 64  AVIA-1052 Please let Matt C know if there are errors or improvements needed. Thanks 65 Previously On AVIA-1052  We talked about …  Some general prop stuff  Aircraft Propeller Theory  Basic Propeller Controls Please let Matt C know if there are errors or improvements needed. Thanks 66 Today On AVIA-1052  We are going to talk about…  Propeller Location  Types of Propellers  Fixed-Pitch Propeller  Test Club Propeller  Ground-Adjustable Propeller  Controllable-Pitch Propeller  Constant-Speed Propellers  Feathering Propellers  Reverse-Pitch Propellers  Propeller Governor Please Propellers let Matt C know if there are Used on General errors or improvements Aviation Aircraft needed. Thanks 67 Where are we?  Powerplant (Vol. 2) 7-6 to 7-14   Start at  Propeller Location  Stop at  Metal Fixed-Pitch Propellers  FAA-H-8083-30A, Aviation Maintenance Technician Handbook-General  FAA-H-8083-31A, Aviation Maintenance Technician Handbook-Airframe Volume 1  FAA-H-8083-31A, Aviation Maintenance Technician Handbook-Airframe Volume 2  FAA-H-8083-32A, Aviation Maintenance Technician Handbook-Powerplant Volume 1 Please FAA-H-8083-32A, let Matt C know if thereAviation are errors orMaintenance Technician improvements needed. Thanks Handbook-Powerplant Volume 2 68  AVIA-1052 Please let Matt C know if there are errors or improvements needed. Thanks 69  Powerplant 7-6 Tractor Propeller  propellers mounted on the upstream end of a drive shaft in front of the supporting structure  most aircraft are equipped with this type of propeller  comes in all types of propellers  major advantage  lower stresses are induced in the propeller as it rotates in relatively undisturbed air Please let Matt C know if there are errors or improvements needed. Thanks 70  Powerplant 7-6 Pusher Propellers  propellers mounted on the downstream end of a drive shaft behind the supporting structure  constructed as fixed- or variable-pitch propellers  mostly used in:  seaplanes  amphibious aircraft Please let Matt C know if there are errors or improvements needed. Thanks 71  Powerplant 7-6 Pusher Propellers  subject to more damage than tractor propellers  in land planes  where propeller-to-ground clearance usually is less than propeller-to-water clearance of watercraft  rocks, gravel, and small objects dislodged by the wheels are quite often thrown or drawn into a pusher propeller  planes with pusher propellers are apt to encounter propeller damage from water spray thrown up by the hull during landing or takeoff airspeed  the pusher propeller is mounted above and behind the wings to prevent such damage Please let Matt C know if there are errors or improvements needed. Thanks 72 Flying Hulls Please let Matt C know if there are errors or improvements needed. Thanks 73 Please let Matt C know if there are errors or improvements needed. Thanks 74  AVIA-1052 Please let Matt C know if there are errors or improvements needed. Thanks 75  Powerplant 7-6 Types of Propellers  various types or classes of propellers  simplest of which are  fixed-pitch  ground-adjustable propellers  complexity of propeller systems increases from these simpler forms to  controllable-pitch  complex constant-speed systems  https://www.youtube.com/watch?v=QKfQ6f6R82Y&t=27s  Constant Speed Prop Basics (6:54) Please let Matt C know if there are errors or improvements needed. Thanks 76  Powerplant 7-6 Fixed-Pitch Propeller  has the blade pitch, or blade angle, built into the propeller  blade angle cannot be changed after the propeller is built  generally, one piece and is constructed of wood or aluminum alloy  designed for best efficiency at one rotational forward speed to fit a set of conditions of both  airplane speeds  engine speeds  any change in these conditions reduces the efficiency of both the propeller and the engine Please let Matt C know if there are errors or improvements needed. Thanks 77  Powerplant 7-7 Fixed-Pitch Propeller  used on airplanes of low:   power  speed  range  altitude  many single-engine aircraft  advantages:  less expensive  simple operation  doesn’t require input from the pilot in flight Please let Matt C know if there are errors or improvements needed. Thanks 78  Powerplant 7-7 Test Club Propeller  used to:  test and break in reciprocating engines  made to:  provide the correct amount of load on the engine during the test break-in period  provide extra cooling air flow during testing Please let Matt C know if there are errors or improvements needed. Thanks 79  Powerplant 7-7 Ground-Adjustable Propeller  operates as a fixed-pitch propeller  pitch can be changed only when the propeller is not turning done by loosening the clamping mechanism that holds the blades in place   after the clamping mechanism has been tightened  the pitch of the blades cannot be changed in flight  to meet variable flight requirements  not often used on present-day airplanes Please let Matt C know if there are errors or improvements needed. Thanks 80  Powerplant 7-7 Controllable-Pitch Propeller  permits a change of blade pitch, or angle, while the propeller is rotating  this allows the propeller to assume a blade angle that gives the best performance for flight conditions  the number of pitch positions may be limited as with a two-position controllable propeller  a Hamilton Standard counterweight two-position propeller is an example Please let Matt C know if there are errors or improvements needed. Thanks 81  Powerplant 7-7 Controllable-Pitch Propeller  the pitch may be adjusted to any angle between the minimum and maximum pitch settings of a given propeller  the blade angle can be changed in flight  but the pilot must change the propeller blade angle directly  the blade angle will not change again until the pilot changes it Please let Matt C know if there are errors or improvements needed. Thanks 82  Powerplant 7-7 Controllable-Pitch Propeller  makes it possible to attain the desired engine rpm for a particular flight condition  not to be confused with a constant speed propeller  the use of a governor is the next step in the evolution of propeller development  making way for constant-speed propellers with governor systems  these types of propeller are not in wide use today Please let Matt C know if there are errors or improvements needed. Thanks 83  Powerplant 7-8 Constant-Speed Propellers  The propeller has a natural tendency to slow down as the aircraft climbs and to speed up as the aircraft dives because the load on the engine varies  To provide an efficient propeller, the speed is kept as constant as possible  By using propeller governors to increase or decrease propeller pitch, the engine speed is held constant  When the airplane goes into a climb, the blade angle of the propeller decreases just enough to prevent the engine speed from decreasing  The engine can maintain its power output if the throttle Please let Matt C knowsetting isor not if there are errors changed improvements needed. Thanks 84  Powerplant 7-8 Constant-Speed Propellers  When the airplane goes into a dive, the blade angle increases sufficiently to prevent overspeeding and, with the same throttle setting, the power output remains unchanged  If the throttle setting is changed instead of changing the speed of the airplane by climbing or diving, the blade angle increases or decreases as required to maintain a constant engine rpm Please let Matt C know if there are errors or improvements needed. Thanks 85  Powerplant 7-8 Constant-Speed Propellers  The power output (not the rpm) changes in accordance with changes in the throttle setting  The governor-controlled, constant-speed propeller changes the blade angle automatically, keeping engine rpm constant  One type of pitch-changing mechanism is operated by oil pressure (hydraulically) and uses a piston-and-cylinder arrangement Please let Matt C know if there are errors or improvements needed. Thanks 86  Powerplant 7-8 Constant-Speed Propellers  The piston may move in the cylinder, or the cylinder may move over a stationary piston  The linear motion of the piston is converted by several different types of mechanical linkage into the rotary motion necessary to change the blade angle  The mechanical connection may be through gears, the pitch-changing mechanism that turns the butt of each blade  Each blade is mounted with a bearing that allows the blade to rotate to change pitch. Please let Matt C know if there are errors or improvements needed. Thanks 87  Powerplant 7-8 Constant-Speed Propellers  In most cases, the oil pressure for operating the different types of hydraulic pitch-changing mechanisms comes directly from the engine lubricating system  When the engine lubricating system is used, the engine oil pressure is usually boosted by a pump that is integral with the governor to operate the propeller  The higher oil pressure (approximately 300 pounds per square inch (psi) provides a quicker blade-angle change  The governors direct the pressurized oil for operation of the hydraulic pitch-changing mechanisms Please let Matt C know if there are errors or improvements needed. Thanks 88  Powerplant 7-8 Constant-Speed Propellers  The governors used to control hydraulic pitch-changing mechanisms are geared to the engine crankshaft and are sensitive to changes in rpm  When rpm increases above the value for which a governor is set, the governor causes the propeller pitch-changing mechanism to turn the blades to a higher angle  This angle increases the load on the engine, and rpm decreases Please let Matt C know if there are errors or improvements needed. Thanks 89  Powerplant 7-8 Constant-Speed Propellers  When rpm decreases below the value for which a governor is set, the governor causes the pitch-changing mechanism to turn the blades to a lower angle; the load on the engine is decreased, and rpm increases  Thus, a propeller governor tends to keep engine rpm constant Please let Matt C know if there are errors or improvements needed. Thanks 90 Constant-Speed Propellers Please let Matt C know if there are errors or improvements needed. Thanks 91  Powerplant 7-8 Constant-Speed Propellers  In constant-speed propeller systems, the control system adjusts pitch using a governor, without attention by the pilot, to maintain a specific preset engine rpm within the set range of the propeller  For example, if engine speed increases, an overspeed condition occurs and the propeller needs to slow down  The controls automatically increase the blade angle until desired rpm has been reestablished Please let Matt C know if there are errors or improvements needed. Thanks 92  Powerplant 7-8 Constant-Speed Propellers  A good constant speed control system responds to such small variations of rpm that for all practical purposes, a constant rpm is maintained  Each constant-speed propeller has an opposing force that operates against the oil pressure from the governor Please let Matt C know if there are errors or improvements needed. Thanks 93  Powerplant 7-8 Constant-Speed Propellers  Flyweights mounted to the blades move the blades in the high pitch direction as the propeller turns  Other forces used to move the blades toward the high pitch direction include air pressure (contained in the front dome), springs, and aerodynamic twisting moment Please let Matt C know if there are errors or improvements needed. Thanks 94  Powerplant 7-10 Propeller Governor  Propeller Blade Flyweights  propeller-governor oil pressure on the propeller piston side balances the propeller blade flyweights  propeller blade flyweight always move the blades toward high pitch  air pressure against the propeller piston pushes toward high pitch  large springs push in the direction of high pitch and feather  centrifugal twisting force  moves the blades toward low pitch Please let Matt C know if there are errors or improvements needed. Thanks 95  Powerplant 7-8 Feathering Propellers  Feathering propellers must be used on multi-engine aircraft to reduce propeller drag to a minimum under one or more engine failure conditions  A feathering propeller is a constant-speed propeller used on multi-engine aircraft that has a mechanism to change the pitch to an angle of approximately 90°  A propeller is usually feathered when the engine fails to develop power to turn the propeller  By rotating the propeller blade angle parallel to the line of flight, the drag on the aircraft is greatly reduced  With the blades parallel to the airstream, the propeller stops turning and minimum windmilling, if any, occurs Please let Matt C know if there are errors or improvements needed. Thanks 96  Powerplant 7-9 Feathering Propellers  Almost all small feathering propellers use oil pressure to take the propeller to low pitch  blade flyweights, springs, and compressed air to take the blades to high pitch  Since the blades would go to the feather position during shutdown, latches lock the propeller in the low pitch position as the propeller slows down at shutdown [Figure 7-14] Please let Matt C know if there are errors or improvements needed. Thanks 97  Powerplant 7-9 Feathering Propellers  These can be internal or external and are contained within the propeller hub  In flight, the latches are prevented from stopping the blades from feathering because they are held off their seat by centrifugal force  Latches are needed to prevent excess load on the engine at start up  If the blade were in the feathered position during engine start, the engine would be placed under an undue load during a time when the engine is already subject to wear Please let Matt C know if there are errors or improvements needed. Thanks 98  Powerplant 7-9 Reverse-Pitch Propellers  Additional refinements, such as reverse- pitch propellers (mainly used on turbo props), are included in some propellers to improve their operational characteristics  Almost all reverse-pitch propellers are of the feathering type  A reverse pitch propeller is a controllable propeller in which the blade angles can be changed to a negative value during operation  The purpose of the reversible pitch feature is to produce a negative blade angle that produces thrust opposite the normal forward direction Please let Matt C know if there are errors or improvements needed. Thanks 99  Powerplant 7-9 Reverse-Pitch Propellers  Normally, when the landing gear is in contact with the runway after landing, the propellers blades can be moved to negative pitch (reversed),which creates thrust opposite of the aircraft direction and slows the aircraft  WOW switches (Weight on wheels squat switches)  As the propeller blades move into negative pitch, engine power is applied to increase the negative thrust  This aerodynamically brakes the aircraft and reduces ground roll after landing. Reversing the propellers also reduces aircraft speed quickly on the runway just after touchdown and minimizes aircraft brake wear Please let Matt C know if there are errors or improvements needed. Thanks 100  AVIA-1052 Please let Matt C know if there are errors or improvements needed. Thanks 101  Powerplant 7-9 Propeller Governor  an engine rpm-sensing device and high-pressure oil pump  responds to a change in engine rpm by either  directing oil under pressure to the propeller hydraulic cylinder  releasing oil from the hydraulic cylinder  in a constant-speed propeller system the change in oil volume in the hydraulic cylinder changes the blade angle   maintains the propeller system rpm  set for a specific rpm via the cockpit propeller control  which compresses or releases the governor speeder spring Pleasehttps://youtu.be/QKfQ6f6R82Y let Matt C know if there are errors or improvements needed. Thanks Constant Speed Prop Basics (6:54) 102  Powerplant 7-9 Propeller Governor  used to sense propeller and engine speed and normally provides oil to the propeller for low pitch position Please let Matt C know if there are errors or improvements needed. Thanks 103  Powerplant 7-9 Propeller Governor  fundamental forces are used to control blade angle variations required for constant- speed propeller operation  these forces are:  centrifugal twisting moment  a component of the centrifugal force acting on a rotating blade that always tends to move the blade into low pitch Please let Matt C know if there are errors or improvements needed. Thanks 104  Powerplant 7-10 Propeller Governor  Aerodynamic twisting force moves the blades toward high pitch  all these forces are not equal in strength  the most powerful force is the governor oil pressure acting on the propeller piston  this piston is connected mechanically to the blades  as the piston moves the blades are rotated in proportion  by removing the oil pressure from the governor, the other forces can force the oil from the piston chamber and move the propeller blades in the other direction Please let Matt C know if there are errors or improvements needed. Thanks 105  Powerplant 7-10 Governor Mechanism  the engine-driven single-acting propeller governor receives oil from the lubricating system and boosts its pressure to that required to operate the pitch-changing mechanism  https://www.youtube.com/watch?v=Z9M_KuP-fbI  Simple Explanation of a Propeller Governor (4:38)  https://www.youtube.com/watch?v=GNsnXjxopJM  ConstantSpeedPropPart1 (14:23) Please let Matt C know if there are errors or improvements needed. Thanks 106  Powerplant 7-10 Governor Mechanism  constant-speed control consists of:  a gear pump  which increases the pressure of the engine oil  a pilot valve  controlled by flyweights in the governor to control the flow of oil through the governor to and away from the propeller  the position of the pilot valve, respective to the propeller-governor metering port, regulates the quantity of oil that flows through this port to or from the propeller  a relief valve system  regulates the operating oil pressures in the governor Please let Matt C know if there are errors or improvements needed. Thanks 107  Powerplant 7-10 Governor Mechanism Please let Matt C know if there are errors or improvements needed. Thanks 108  Powerplant 7-11 Governor Mechanism  Figure 7-16 Please let Matt C know if there are errors or improvements needed. Thanks 109  Powerplant 7-11 Governor Mechanism  Figure 7-16 Please let Matt C know if there are errors or improvements needed. Thanks 110  Powerplant 7-10 Governor Mechanism  constant-speed control consists of: (continued)  a spring called the speeder spring  opposes the governor flyweight’s ability to fly outward when turning  if the flyweights turn faster than the tension on the speeder spring, they fly out  this is an over-speed condition  to slow the engine propeller combination down  blade pitch must be increased  oil is allowed to flow away from the propeller piston  flyweights on the prop increase the pitch  slowing the propeller until it is on-speed  where the force on the governor flyweights and the tension on the speeder spring are balanced Please let Matt C know if there are errors or improvements needed. Thanks 111  Powerplant 7-10 Governor Mechanism  this balance of forces can be disturbed by  the aircraft changing attitude (climb or dive)  tension on this spring  can be adjusted by the propeller control on the control quadrant  sets the maximum rpm of the engine in the governor mode Please let Matt C know if there are errors or improvements needed. Thanks 112  Powerplant 7-10 Governor Mechanism  as the engine and propeller rpm is increased at the maximum set point of the governor (maximum speed)  the governor flyweights overcome the tension of the speeder spring and move outward  this action moves the pilot valve in the governor to release oil from the propeller piston  allows the blade flyweights to increase blade pitch  which increases the load on the engine  slowing it down or maintaining the set speed Please let Matt C know if there are errors or improvements needed. Thanks 113  Powerplant 7-10 Governor Mechanism  the governor maintains the required balance between control forces by either  metering to  draining from  the propeller piston the exact quantity of oil necessary to maintain the proper blade angle for constant-speed operation Please let Matt C know if there are errors or improvements needed. Thanks 114  Powerplant 7-10 Propeller Governor  Underspeed Condition  the governor is operating in an under-speed condition when the engine is operating below the rpm set by the pilot using the cockpit control [Figure 7-17] Please let Matt C know if there are errors or improvements needed. Thanks 115  Powerplant 7-10 Propeller Governor  Underspeed Condition (continued)  in this condition:  flyweights tilt inward  because there is not enough centrifugal force on the flyweights to overcome the force of the speeder spring  the pilot valve is forced down by the speeder spring  meters oil flow to decrease propeller pitch and raise engine rpm Please let Matt C know if there are errors or improvements needed. Thanks 116  Powerplant 7-10 Propeller Governor  Underspeed Condition (continued)  if the nose of the aircraft is raised or the blades are moved to a higher blade angle, this increases the load on the engine and the propeller tries to slow down  to maintain a constant speed, the governor senses the decrease in speed and  increases oil flow to the propeller  moving the blades to a lower pitch  allowing them to maintain the same speed Please let Matt C know if there are errors or improvements needed. Thanks 117  Powerplant 7-10 Propeller Governor  Underspeed Condition (continued)  When the engine speed starts to drop below the rpm for which the governor is set  the resulting decrease in centrifugal force exerted by the flyweights permits the speeder spring to lower the pilot valve (flyweights inward)  thereby opening the propeller-governor metering port  the oil then flows through the valve port and into the propeller piston  causing the blades to move to a lower pitch (a decrease in load) Please let Matt C know if there are errors or improvements needed. Thanks 118  Powerplant 7-10 Propeller Governor  Overspeed Condition  the governor is operating in an over-speed condition  when the engine is operating above the rpm set by the pilot using the cockpit control Please let Matt C know if there are errors or improvements needed. Thanks 119  Powerplant 7-10 Propeller Governor  Overspeed Condition (continued)  in an over-speed condition:  the centrifugal force acting on the flyweights is greater than the speeder spring force  the flyweights tilt outward and raise the pilot valve  the pilot valve then meters oil flow to increase propeller pitch and lower engine rpm Please let Matt C know if there are errors or improvements needed. Thanks 120  Powerplant 7-10 Propeller Governor  when the engine speed increases above the rpm for which the governor is set:  note that the flyweights move outward against the force of the speeder spring  raising the pilot valve  this opens the propeller-governor metering port  allowing governor oil flow from the propeller piston allowing counterweights on the blades to:  increase pitch  slow the engine Please let Matt C know if there are errors or improvements needed. Thanks 121  Powerplant 7-10 Propeller Governor  On-Speed Condition  the governor is operating on speed  when the engine is operating at the rpm set by the pilot using the cockpit control Please let Matt C know if there are errors or improvements needed. Thanks 122  Powerplant 7-10 Propeller Governor  On-Speed Condition (continued)  in an on-speed condition:  the centrifugal force acting on the flyweights is balanced by the speeder spring  the pilot valve is neither directing oil to nor from the propeller hydraulic cylinder Please let Matt C know if there are errors or improvements needed. Thanks 123  Powerplant 7-11 Propeller Governor  On-Speed Condition (continued)  the forces of the governor flyweights and the tension on the speeder spring are equal  the propeller blades are not moving or changing pitch  if something happens to unbalance these forces  such as:  if the aircraft:  dives  climbs Please let Matt C know if there are errors or improvements needed. Thanks 124  Powerplant 7-11 Propeller Governor  On-Speed Condition (continued)  if the pilot selects a new rpm range through the propeller control(changes tension on the speeder spring)  a change in rpm comes about in the governing mode by pilot selection of a new position of the propeller control which changes the tension of the governor speeder spring or by the aircraft changing attitude Please let Matt C know if there are errors or improvements needed. Thanks 125  Powerplant 7-11 Propeller Governor  On-Speed Condition (continued) then these forces are unequal   an under-speed or over-speed condition would result  the governor  a speed-sensing device  causes the propeller to maintain a set rpm regardless of the aircraft attitude  the speeder spring propeller governing range is limited to about 200 rpm  the governor cannot maintain the correct rpm beyond this rpm Please let Matt C know if there are errors or improvements needed. Thanks 126  Powerplant 7-12 Propeller Governor  Governor System Operation  If the engine speed drops below the rpm for which the governor is set, the rotational force on the engine-driven governor flyweights becomes less. [Figure 7-17] Please let Matt C know if there are errors or improvements needed. Thanks 127  Powerplant 7-12 Propeller Governor  Governor System Operation  This allows the speeder spring to move the pilot valve downward. With the pilot valve in the downward position, oil from the gear type pump flows through a passage to the propeller and moves the cylinder outward.  This in turn decreases the blade angle and permits the engine to return to the on-speed setting. Please let Matt C know if there are errors or improvements needed. Thanks 128  Powerplant 7-12 Propeller Governor  Governor System Operation (continued)  If the engine speed increases above the rpm for which the governor is set, the flyweights move against the force of the speeder spring and raise the pilot valve.  This permits the oil in the propeller to drain out through the governor drive shaft.  As the oil leaves the propeller, the centrifugal force acting on the counterweights turns the blades to a higher angle, which decreases the engine rpm. Please let Matt C know if there are errors or improvements needed. Thanks 129  Powerplant 7-12 Propeller Governor  Governor System Operation (continued)  When the engine is exactly at the rpm set by the governor, the centrifugal reaction of the flyweights balances the force of the speeder spring, positioning the pilot valve so that oil is neither supplied to nor drained from the propeller.  With this condition, propeller blade angle does not change. Note that the rpm setting is made by varying the amount of compression in the speeder spring.  Positioning of the speeder rack is the only action controlled manually.  All others are controlled automatically within the governor. Please let Matt C know if there are errors or improvements needed. Thanks 130  Powerplant 7-12 https://youtu.be/TR7KZdHLkE4 Airplane Propellers (5:32) Please let Matt C know if there are errors or improvements needed. Thanks 131  AVIA-1052 Please let Matt C know if there are errors or improvements needed. Thanks 132  Powerplant 7-12 Propellers Used on General Aviation Aircraft  an increasing number of light aircraft are designed for operation with governor-regulated, constant-speed propellers  significant segments of general aviation aircraft are still operated with fixed-pitch propellers  light sport aircraft (LSA) use multi-blade fixed-pitch composite propellers on up to medium size turbo prop aircraft with reversing propeller systems  larger transport and cargo turbo prop aircraft use propeller systems with dual or double-acting governors and differential oil pressure to change pitch Please let Matt C know if there are errors or improvements needed. Thanks 133  AVIA-1052 Please let Matt C know if there are errors or improvements needed. Thanks 134  Powerplant 7-12 Fixed-Pitch Wooden Propellers  although many of the wood propellers were used on older airplanes, some are still in use  the construction of a fixed-pitch, wooden propeller is such that its blade pitch cannot be changed after manufacture [Figure 7-20] Please let Matt C know if there are errors or improvements needed. Thanks 135  Powerplant 7-12 Fixed-Pitch Wooden Propellers  the choice of the blade angle is decided by the normal use of the propeller on an aircraft during level flight when the engine performs at maximum efficiency  the impossibility of changing the blade pitch on the fixed-pitch propeller restricts its use to small aircraft  with low horsepower engines in which maximum engine efficiency during all flight conditions is of lesser importance than in larger aircraft  well suited for such small aircraft because of its  light weight  rigidity  economy of production  simplicity of construction  ease of replacement Please let Matt C know if there are errors or improvements needed. Thanks 136  Powerplant 7-13 Fixed-Pitch Wooden Propellers  construction  not constructed from a solid block  built up of 5-9 layers of carefully selected and well-seasoned hardwoods  birch  most widely used  mahogany  cherry  black walnut  oak  each layer about ¾ inch thick  glued together with a waterproof, resinous glue and allowed to set Please let Matt C know if there are errors or improvements needed. Thanks 137  Powerplant 7-13 Fixed-Pitch Wooden Propellers  roughed to the approximate shape and size of the finished product  allowed to dry for approximately one week to permit the moisture content of the layers to become equalized  to prevent warping and cracking which might occur if the blank were immediately carved  the propeller is carefully constructed  templates and bench protractors are used to assure the proper contour and blade angle at all stations Please let Matt C know if there are errors or improvements needed. Thanks 138  Powerplant 7-13 Fixed-Pitch Wooden Propellers  a fabric covering is cemented  to the outer 12 or 15 inches of each finished blade  a metal tipping terneplate   Monel metal  brass  stainless steel  is fastened to most of the leading edge and the tip of each blade Please let Matt C know if there are errors or improvements needed. Thanks 139  Powerplant 7-13 Fixed-Pitch Wooden Propellers  to protect the propeller from damage caused by flying particles in the air during:  landing  taxiing  takeoff [Figure 7-21]  by using countersunk wood screws and rivets  heads of screws are soldered to the tipping to prevent loosening  solder is filed to make a smooth surface  small holes are provided near the blade tip to allow condensation to drain away or be thrown out by centrifugal force  these drain holes must be always kept open Please let Matt C know if there are errors or improvements needed. Thanks 140  Powerplant 7-13 Fixed-Pitch Wooden Propellers  [Figure 7-21] Please let Matt C know if there are errors or improvements needed. Thanks 141  Powerplant 7-13 Fixed-Pitch Wooden Propellers  a protective coating is applied to the finished propeller to prevent a rapid change of moisture content  to prevent:  swelling  shrinking  warping  the finish most used is a series of coats of water-repellent, clear varnish  the propeller is mounted on a spindle and very carefully balanced Please let Matt C know if there are errors or improvements needed. Thanks 142  Powerplant 7-13 Fixed-Pitch Wooden Propellers  hubs  used to mount wooden propellers on the engine crankshaft forged steel hub that fits a splined crankshaft   may be connected to a tapered crankshaft  by a tapered, forged steel hub  may be bolted to a steel flange forged on the crankshaft Please let Matt C know if there are errors or improvements needed. Thanks 143  Powerplant 7-13 Fixed-Pitch Wooden Propellers  Hubs (continued)  several attaching parts are required to mount the propeller on the shaft properly  hubs fitting a tapered shaft are usually held in place by a retaining nut that screws onto the end of the shaft  a locknut is used to safety the retaining nut and to provide a puller for removing the propeller from the shaft on one model  this nut screws into the hub and against the retaining nut  the locknut and the retaining nut are safetied together with lock-wire or a cotter pin Please let Matt C know if there are errors or improvements needed. Thanks 144  Powerplant 7-13 Fixed-Pitch Wooden Propellers  Hubs (continued)  steel fitting inserted in the propeller to mount it on the propeller shaft  two main parts  Faceplate-steel disk that forms the forward face of the hub Please let Matt C know if there are errors or improvements needed. Thanks 145  Powerplant 7-13 Fixed-Pitch Wooden Propellers  Hubs (continued)  flange plate steel flange with an internal bore splined to receive the  propeller shaft  the end of the flange plate opposite the flange disk is externally splined to receive the faceplate  the faceplate bore has splines to match these external splines  the flange plate bore has a 15° cone seat on the rear end and a 30° cone seat on the forward end  to center the hub accurately on the propeller shaft  both have a corresponding series of holes drilled on the disk surface concentric with the hub center Please let Matt C know if there are errors or improvements needed. Thanks 146  Powerplant 7-14 Fixed-Pitch Wooden Propellers  Hubs (continued) Please let Matt C know if there are errors or improvements needed. Thanks 147  Powerplant 7-13 Fixed-Pitch Wooden Propellers  Hubs (continued)  cones  front and rear cones may be used to seat the propeller properly on a splined shaft  rear cone  one-piece bronze cone  fits around the shaft and against the thrust nut (or spacer)  seats in the rear-cone seat of the hub Please let Matt C know if there are errors or improvements needed. Thanks 148  Powerplant 7-14 Fixed-Pitch Wooden Propellers  Hubs (continued)  spacers  sometimes provided with the splined-shaft propeller assembly  to prevent the propeller from interfering with the engine cowling  the wide flange on the rear face of some types of hubs eliminates the use of a rear-cone spacer Please let Matt C know if there are errors or improvements needed. Thanks 149  Powerplant 7-14 Fixed-Pitch Wooden Propellers  Hubs (continued)  front cone  two-piece, split-type steel cone  has a groove around its inner circumference  so that it can be fitted over a flange of the propeller retaining nut  the retaining nut is threaded into place  the front cone seats in the front cone hub  a snap ring is fitted into a groove in the hub in front of the front cone  so that when the retaining nut is unscrewed from the propeller shaft, the front cone acts against the snap ring and pulls the propeller from the shaft Please let Matt C know if there are errors or improvements needed. Thanks 150  Powerplant 7-14 Fixed-Pitch Wooden Propellers Please let Matt C know if there are errors or improvements needed. Thanks 151  Powerplant 7-14 Fixed-Pitch Wooden Propellers  Hubs (continued)  bronze bushing  used instead of a front cone in one type of hub  it may be necessary to use a puller to start the propeller from the shaft Please let Matt C know if there are errors or improvements needed. Thanks 152  AVIA-1052 Please let Matt C know if there are errors or improvements needed. Thanks 153 Previously On AVIA-1052  Well, we talked about…  Propeller Location  Types of Propellers  Fixed-Pitch Propeller  Test Club Propeller  Ground-Adjustable Propeller  Controllable-Pitch Propeller  Constant-Speed Propellers  Feathering Propellers  Reverse-Pitch Propellers  Propeller Governor Please Propellers let Matt C know if there are Used on General errors or improvements Aviation Aircraft needed. Thanks 154 Today On AVIA-1052  We are going to talk about…  Propellers Used on General Aviation Aircraft  The never-ending story  Metal Fixed-Pitch Propellers  Hartzell Constant-Speed, Non-feathering  Constant-Speed Feathering Propeller  Unfeathering  Ice Control Systems  Anti-Ice  Deice  Propeller Synchronization and Synchrophasing Please Autofeathering let Matt System C know if there are errors or improvements needed. Thanks 155 Where are we?  Powerplant 7-12 to 7-20   Start at  Metal Fixed-Pitch Propellers  Stop at  Propeller Inspection and Maintenance  FAA-H-8083-30A, Aviation Maintenance Technician Handbook-General  FAA-H-8083-31A, Aviation Maintenance Technician Handbook-Airframe Volume 1  FAA-H-8083-31A, Aviation Maintenance Technician Handbook-Airframe Volume 2  FAA-H-8083-32A, Aviation Maintenance Technician Handbook-Powerplant Volume 1 Please FAA-H-8083-32A, let Matt C know if thereAviation are errors orMaintenance Technician improvements needed. Thanks Handbook-Powerplant Volume 2 156  AVIA-1052 Please let Matt C know if there are errors or improvements needed. Thanks 157  AVIA-1052 Please let Matt C know if there are errors or improvements needed. Thanks 158  Powerplant 7-14 Metal Fixed-Pitch Propellers  similar in general appearance to a wooden propeller  usually, thinner sections  widely used on many models of  light aircraft  LSA (Light Sport Aircraft)  many of the earliest metal propellers were manufactured in one piece of forged Duralumin Please let Matt C know if there are errors or improvements needed. Thanks 159  Powerplant 7-14 Metal Fixed-Pitch Propellers  compared to wooden propellers lighter   elimination of blade-clamping devices  lower maintenance cost  made in one piece  more efficient cooling  effective pitch nearer the hub  the propeller pitch could be changed  within limits  by twisting the blade slightly by a propeller repair station because there was no joint between the blades and the hub Please let Matt C know if there are errors or improvements needed. Thanks 160  Powerplant 7-14 Metal Fixed-Pitch Propellers  now manufactured as one-piece anodized aluminum alloy  identified by stamping the propeller hub with the  serial number  complete model number  combination of basic model number and suffix numbers  indicate  the propeller diameter  the propeller pitch  FAA type certificate number  production certificate number  number of times the propeller has been reconditioned Please let Matt C know if there are errors or improvements needed. Thanks 161  Powerplant 7-14 Metal Fixed-Pitch Propellers Please let Matt C know if there are errors or improvements needed. Thanks 162  AVIA-1052 Please let Matt C know if there are errors or improvements needed. Thanks 163  Powerplant 7-14 Hartzell Constant-Speed, Non-feathering  Hartzell propellers can be divided by Aluminum hub (compact) and steel hub  Hartzell compact aluminum propellers represent new concepts in basic design  They combine low weight and simplicity in design and rugged construction  In order to achieve these ends, the hub is made as compact as possible, utilizing aluminum alloy forgings for most of the parts  The hub shell is made in two halves, bolted together along the plane of rotation  This hub shell carries the pitch change mechanism and blade roots internally Please let Matt C know if there are errors or improvements needed. Thanks 164  Powerplant 7-14 Hartzell Constant-Speed, Non-feathering  The hydraulic cylinder, which provides power for changing the pitch, is mounted at the front of the hub  The propeller can be installed only on engines with flanged mounting provisions  One model of non-feathering aluminum hub constant-speed propeller utilizes oil pressure from a governor to move the blades into high pitch (reduced rpm)  The centrifugal twisting moment of the blades tends to move them into low pitch (high rpm) in the absence of governor oil pressure  This is an exception to most of the aluminum hub models and feathering models  https://youtu.be/tIAfmY42siI ConstantSpeedPropPart2 (9:42) Please let Matt C know if there are errors or improvements needed. Thanks 165  Powerplant 7-15 Hartzell Constant-Speed, Non-feathering  Most of the Hartzell propeller aluminum and steel hub models use centrifugal force acting on blade counterweights to increase blade pitch and governor oil pressure for low pitch  Many types of light aircraft use governor-regulated, constant-speed propellers in two-bladed and up to six- bladed versions  These propellers may be the non- feathering type, or they may be capable of feathering and reversing Please let Matt C know if there are errors or improvements needed. Thanks 166  Powerplant 7-15 Hartzell Constant-Speed, Non-feathering  The steel hub contains a central “spider,” that supports aluminum blades with a tube extending inside the blade roots  Blade clamps connect the blade shanks with blade retention bearings Please let Matt C know if there are errors or improvements needed. Thanks 167  Powerplant 7-15 Hartzell Constant-Speed, Non-feathering  A hydraulic cylinder is mounted on the rotational axis connected to the blade clamps for pitch actuation  The basic hub and blade retention is common to all models described  The blades are mounted on the hub spider for angular adjustment  The centrifugal force of the blades, amounting to as much as 25 tons, is transmitted to the hub spider through blade clamps and then through ball bearings  The propeller thrust and engine torque is transmitted from the blades to the hub spider through a bushing inside the blade shank Please let Matt C know if there are errors or improvements needed. Thanks 168  Powerplant 7-15 Hartzell Constant-Speed, Non-feathering  Please let Matt C know if there are errors or improvements needed. Thanks 169  Powerplant 7-15 Hartzell Constant-Speed, Non-feathering  In order to control the pitch of the blades, a hydraulic piston-cylinder element is mounted on the front of the hub spider  The piston is attached to the blade clamps by means of a sliding rod and fork system for non- feathering models and a link system for the feathering models Please let Matt C know if there are errors or improvements needed. Thanks 170  Powerplant 7-15 Hartzell Constant-Speed, Non-feathering  The piston is actuated in the forward direction by means of oil pressure supplied by a governor, which overcomes the opposing force created by the counterweights  Hartzell and McCauley propellers for light aircraft are similar in operation  The manufacturer’s specifications and instructions must be consulted for information on specific models Please let Matt C know if there are errors or improvements needed. Thanks 171  AVIA-1052 Please let Matt C know if there are errors or improvements needed. Thanks 172  Powerplant 7-15 Constant-Speed Feathering Propeller  The feathering propeller utilizes a single oil supply from a governing device to hydraulically actuate a change in blade angle [Figure 7-25]  This propeller has five blades and is used primarily on Pratt & Whitney turbine engines  A two-piece aluminum hub retains each propeller blade on a thrust bearing  A cylinder is attached to the hub and contains a feathering spring and piston  The hydraulically actuated piston transmits linear motion through a pitch change rod and fork to each blade to result in blade angle change Please let Matt C know if there are errors or improvements needed. Thanks 173  Powerplant 7-16 Constant-Speed Feathering Propeller  Please let Matt C know if there are errors or improvements needed. Thanks 174  Powerplant 7-16 Constant-Speed Feathering Propeller Please let Matt C know if there are errors or improvements needed. Thanks 175  Powerplant 7-15 Constant-Speed Feathering Propeller  While the propeller is operating, the following forces are constantly present:  spring force,  counterweight force  centrifugal twisting moment of each blade, and  blade aerodynamic twisting forces  The spring and counterweight forces attempt to rotate the blades to higher blade angle, while the centrifugal twisting moment of each blade is generally toward lower blade angle  Blade aerodynamic twisting force is usually very small in relation to the other forces and can attempt to increase or decrease blade angle Please let Matt C know if there are errors or improvements needed. Thanks 176  Powerplant 7-16 Constant-Speed Feathering Propeller  the propeller forces move the blades toward higher pitch (low rpm)  These forces are opposed by a variable force toward lower pitch (high rpm)  The variable force is oil under pressure from a governor with an internal pump that is mounted on and driven by the engine  The oil from the governor is supplied to the propeller and hydraulic piston through a hollow engine shaft  Increasing the volume of oil within the piston and cylinder decreases the blade angle and increases propeller rpm  If governor-supplied oil is lost during operation, the propeller increases pitch and feathers  https://youtu.be/DvWKfu4ubik  How it's Made, Airplane Propellers (4:58) Please let Matt C know if there are errors or improvements needed. Thanks 177  Powerplant 7-16 Constant-Speed Feathering Propeller  Feathering occurs because the internal propeller forces push the oil out of the propeller until the feather stop position is reached  Normal in-flight feathering is accomplished when the pilot retards the propeller condition lever past the feather detent  This permits control oil to drain from the propeller and return to the engine sump  Engine shutdown is normally accomplished during the feathering process  Normal in-flight unfeathering is accomplished when the pilot positions the propeller condition lever into the normal flight (governing) range and restarts the engine Please let Matt C know if there are errors or improvements needed. Thanks 178  Powerplant 7-16 Constant-Speed Feathering Propeller  As engine speed increases, the governor supplies oil to the propeller and the blade angle decreases  Decreasing the volume of oil increases blade angle and decrease propeller rpm  By changing blade angle, the governor can vary the load on the engine and maintain constant engine rpm (within limits), independent of where the power lever is set  The governor uses engine speed sensing mechanisms that permit it to supply or drain oil as necessary to maintain constant engine speed (rpm)  Most of the steel hub Hartzell propellers and many of the aluminum hub are full feathering Please let Matt C know if there are errors or improvements needed. Thanks 179  Powerplant 7-16 Constant-Speed Feathering Propeller  These feathering propellers operate similarly to the non- feathering ones except the feathering spring assists the counterweights to increase the pitch  Feathering is accomplished by releasing the governor oil pressure, allowing the counterweights and feathering spring to feather the blades.  This is done by pulling the condition lever (pitch control) back to the limit of its travel, which opens a port in the governor allowing the oil from the propeller to drain back into the engine  Feathering occurs