Podcast
Questions and Answers
What happens to the propeller if the engine runs out of oil?
What happens to the propeller if the engine runs out of oil?
Which method allows the propeller to unfeather quickly using engine oil?
Which method allows the propeller to unfeather quickly using engine oil?
What can trigger feathering of the propeller in light twins?
What can trigger feathering of the propeller in light twins?
Which of the following describes how an accumulator contributes to unfeathering?
Which of the following describes how an accumulator contributes to unfeathering?
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In normal in-flight unfeathering, what action is taken with the propeller condition lever?
In normal in-flight unfeathering, what action is taken with the propeller condition lever?
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What is a potential consequence of unfeathering the propeller too quickly?
What is a potential consequence of unfeathering the propeller too quickly?
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Which component collects and manages oil pressure for propeller operation?
Which component collects and manages oil pressure for propeller operation?
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What role does the unfeathering pump play in propeller management?
What role does the unfeathering pump play in propeller management?
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What is the primary action taken to initiate the feathering process of a propeller?
What is the primary action taken to initiate the feathering process of a propeller?
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What factors influence the time necessary for feathering?
What factors influence the time necessary for feathering?
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What function do spring-loaded latches serve in a feathering propeller system?
What function do spring-loaded latches serve in a feathering propeller system?
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What typically happens during the feathering process when the engine is shut down?
What typically happens during the feathering process when the engine is shut down?
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What is the usual elapsed time for feathering in constant-speed feathering propellers?
What is the usual elapsed time for feathering in constant-speed feathering propellers?
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What safety feature allows the propeller to feather automatically?
What safety feature allows the propeller to feather automatically?
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What role does the centrifugal force play when the propeller is rotating at high speeds?
What role does the centrifugal force play when the propeller is rotating at high speeds?
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At what RPM do the spring-loaded latches typically disengage from the high pitch stop plates?
At what RPM do the spring-loaded latches typically disengage from the high pitch stop plates?
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What is the main advantage of metal fixed-pitch propellers over wooden propellers?
What is the main advantage of metal fixed-pitch propellers over wooden propellers?
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Which component of the Hartzell constant-speed non-feathering propeller is responsible for changing the blade pitch?
Which component of the Hartzell constant-speed non-feathering propeller is responsible for changing the blade pitch?
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What happens to the blade angle of a constant-speed feathering propeller if the governor oil pressure is lost?
What happens to the blade angle of a constant-speed feathering propeller if the governor oil pressure is lost?
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Which of the following is NOT a characteristic of Hartzell constant-speed propellers?
Which of the following is NOT a characteristic of Hartzell constant-speed propellers?
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How is the pitch of the blades adjusted in a Hartzell constant-speed propeller?
How is the pitch of the blades adjusted in a Hartzell constant-speed propeller?
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In constant-speed feathering propellers, what role does the feathering spring play?
In constant-speed feathering propellers, what role does the feathering spring play?
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Which of the following best describes a feature of metal fixed-pitch propellers?
Which of the following best describes a feature of metal fixed-pitch propellers?
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What is the typical construction material for early metal fixed-pitch propellers?
What is the typical construction material for early metal fixed-pitch propellers?
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What occurs during the feathering process of a propeller in flight?
What occurs during the feathering process of a propeller in flight?
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How does a pilot unfeather a propeller in-flight?
How does a pilot unfeather a propeller in-flight?
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What describes the operational principle of a constant-speed feathering propeller?
What describes the operational principle of a constant-speed feathering propeller?
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What distinguishes Hartzell aluminum hub propellers from others?
What distinguishes Hartzell aluminum hub propellers from others?
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Which factor is not directly involved in blade angle adjustment in a constant-speed feathering propeller?
Which factor is not directly involved in blade angle adjustment in a constant-speed feathering propeller?
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What happens to the propeller blade angle when the engine starts during normal unfeathering?
What happens to the propeller blade angle when the engine starts during normal unfeathering?
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What role does the governor play in the unfeathering process?
What role does the governor play in the unfeathering process?
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What is the effect of windmilling during the unfeathering process?
What is the effect of windmilling during the unfeathering process?
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What is the purpose of using an accumulator in the unfeathering process?
What is the purpose of using an accumulator in the unfeathering process?
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What occurs when reciprocating unfeathering is utilized?
What occurs when reciprocating unfeathering is utilized?
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How does an unfeathering pump function during the unfeathering process?
How does an unfeathering pump function during the unfeathering process?
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What mechanism enables unfeathering on the ground?
What mechanism enables unfeathering on the ground?
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What is one potential consequence during the unfeathering process?
What is one potential consequence during the unfeathering process?
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What is the primary function of the slip ring in an electric propeller-icing control system?
What is the primary function of the slip ring in an electric propeller-icing control system?
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Which of the following components is used to electrically connect the deice boot to the slip ring assembly?
Which of the following components is used to electrically connect the deice boot to the slip ring assembly?
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How does the electric propeller-icing control system primarily remove ice from the propeller blades?
How does the electric propeller-icing control system primarily remove ice from the propeller blades?
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What must be controlled to ensure balanced ice removal from all blades in a propeller deicing system?
What must be controlled to ensure balanced ice removal from all blades in a propeller deicing system?
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What is the role of cycling timers in an electric propeller-icing control system?
What is the role of cycling timers in an electric propeller-icing control system?
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Which system is specifically designed to feather the propeller automatically if engine power is lost?
Which system is specifically designed to feather the propeller automatically if engine power is lost?
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What condition activates the solenoid valve in an auto-feathering system?
What condition activates the solenoid valve in an auto-feathering system?
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In a multi-engine aircraft, what is the main purpose of propeller synchronization systems?
In a multi-engine aircraft, what is the main purpose of propeller synchronization systems?
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What is an important design consideration for the heating element in the deice boot?
What is an important design consideration for the heating element in the deice boot?
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What is the maximum complete cycle time for the electric propeller-icing control system?
What is the maximum complete cycle time for the electric propeller-icing control system?
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What is the purpose of current limiters in the propeller electrical deicing system?
What is the purpose of current limiters in the propeller electrical deicing system?
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Which switches are found in the controls for propeller electrical deicing systems?
Which switches are found in the controls for propeller electrical deicing systems?
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What happens if heat is supplied more than what is necessary for melting the inner ice face?
What happens if heat is supplied more than what is necessary for melting the inner ice face?
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Which sequence describes the order of propeller deice activation on the Navajo PA31?
Which sequence describes the order of propeller deice activation on the Navajo PA31?
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What is the primary consequence of ice formation on a propeller blade?
What is the primary consequence of ice formation on a propeller blade?
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Which component is NOT typically included in a Fluid Anti-Ice system?
Which component is NOT typically included in a Fluid Anti-Ice system?
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What fluid is commonly used in Fluid Anti-Ice systems due to its properties?
What fluid is commonly used in Fluid Anti-Ice systems due to its properties?
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What is the function of feed shoes in a Fluid Anti-Ice system?
What is the function of feed shoes in a Fluid Anti-Ice system?
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What role does the slinger ring play in a Fluid Anti-Ice system?
What role does the slinger ring play in a Fluid Anti-Ice system?
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What is a major disadvantage of Fluid Anti-Ice systems?
What is a major disadvantage of Fluid Anti-Ice systems?
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Which component is essential for the operation of an electric propeller-icing control system?
Which component is essential for the operation of an electric propeller-icing control system?
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What is the purpose of the timer in an electric propeller-icing control system?
What is the purpose of the timer in an electric propeller-icing control system?
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What adjustment might a selector switch in an electric deicing system make?
What adjustment might a selector switch in an electric deicing system make?
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Why are electric deicing systems increasingly preferred over Fluid Anti-Ice systems in modern aircraft?
Why are electric deicing systems increasingly preferred over Fluid Anti-Ice systems in modern aircraft?
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What type of icing issue does asymmetrical ice formation lead to on a propeller?
What type of icing issue does asymmetrical ice formation lead to on a propeller?
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What material is commonly NOT used in Fluid Anti-Ice systems due to its cost?
What material is commonly NOT used in Fluid Anti-Ice systems due to its cost?
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What aspect does the control system of a Fluid Anti-Ice system allow for?
What aspect does the control system of a Fluid Anti-Ice system allow for?
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Where is the resistance heating element typically mounted in an electric deicing system?
Where is the resistance heating element typically mounted in an electric deicing system?
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Study Notes
Week 1 of 1 Day 3 - AVIA-1052
- Course title is AVIA-1052
- The course is about propellers used in general aviation aircraft
- The course covers topics from Powerplant 7-12 to 7-20
- Specific topics: Propeller Location, Types of Propellers, Metal Fixed-Pitch Propellers, Hartzell Constant-Speed, Non-feathering, Constant-Speed Feathering Propeller, Unfeathering, Ice Control Systems, Anti-Ice, Deice, Propeller Synchronization and Synchrophasing, Autofeathering System
Propeller Location
- No specific details given
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
- Propellers Used on General Aviation Aircraft
Metal Fixed-Pitch Propellers
- Similar in appearance to wooden propellers.
- Usually thinner sections.
- Widely used in many light aircraft models, including LSA (Light Sport Aircraft).
- Many early metal propellers were forged from Duralumin in one piece.
- Compared to wooden propellers, they are lighter and eliminate blade-clamping devices.
- Lower maintenance cost due to being made in one piece.
- More efficient cooling.
- Effective pitch is nearer the hub.
- Propeller pitch can be changed within limits by twisting the blade, eliminating the joint between the blade and the hub.
- Now manufactured as one-piece anodized aluminum alloy, identified by stamping.
- Serial number, complete model number, combination of basic model number and suffix numbers, diameter, pitch, FAA type certificate number, and production certificate number; number of times reconditioned.
- Inches pitch at 0.75 radius.
- Includes various designations (CF, CH, CM, LF) referring to installation on specific shaft types and blade tip shapes.
- Basic design number (planform, etc.)
Hartzell Constant-Speed, Non-feathering
- Hartzell propellers are available with aluminum and steel hubs.
- Compact design, combining low weight and simple construction.
- The hub is made from aluminum alloy forgings in two halves.
- The hub shell carries the pitch change mechanism and blade roots internally.
- The hydraulic cylinder, for changing pitch, is mounted at the front of the hub.
- Non-feathering aluminum hub constant-speed propellers use oil pressure from a governor to move the blades.
- Centrifugal force tends to move the blades to low pitch (high rpm) without governor oil pressure.
- This is different from most aluminum hub and feathering models.
- An online video is referenced (https://youtu.be/tlAfmY42sil ConstantSpeedPropPart2 (9:42)).
- Made from aluminum and steel hub, using centrifugal force to increase blade pitch and governor oil pressure to low pitch.
- Common in light aircraft.
Constant-Speed Feathering Propeller
- Feathering propellers use a single oil supply from the governor to hydraulically actuate blade angle changes.
- Five-bladed models are primarily used on Pratt & Whitney turbine engines.
- Propeller blades are mounted on a two-piece aluminum hub via a thrust bearing.
- A cylinder, containing a feathering spring and piston, is attached to the hub.
- The hydraulically-actuated piston transmits linear motion to each blade through a pitch change rod and fork, resulting in changes in blade angles. The references mention a diagram in Figure 7-25.
Unfeathering
- Methods for unfeathering: Starting the engine, the governor can pump oil back into the propeller to reduce pitch, in most light twins, this procedure is considered adequate since most light or twin aircraft rarely experience feathering issues and May vibrate once it comes out of feathering.
- Using An accumulator: The accumulator traps oil-air pressure, releasing it quickly when rpm control returns to its normal position and the engine begins to windmill.
- Unfeathering pump: Provides pressure to move the propeller back to low pitch swiftly using engine oil.
- Ground unfeathering: Can be done using blade paddles.
Ice Control Systems
- Ice formation on propeller blades produces distorted airfoil sections, reducing efficiency and creating vibrations—increasing the weight of the blades.
- https://youtu.be/ezota GRnnE (aircraft propeller ice tests for conventional electric de-ice system at 2100 RPM).
Anti-Icing Systems
- Fluid anti-icing systems typically include a tank, pump, and control system to supply anti-icing fluid to propellers, adjusting the flow to varying degrees/severity of ice.
- Fluid types: Isopropyl alcohol (high availability, low cost), phosphate compounds (reduced flammability, more expensive, less common).
Deicing Systems
- Consist of an electrical energy source and heating elements mounted on propeller spinner and blades.
- Has internally and externally-system controls and necessary wiring
- Includes a master switch, optional toggle/selector switch for each propeller, adjusted for icing conditions, (light/heavy), and timer for determining the sequence of which blades and for what length of deicing.
- Includes a cycling unit to energize the heating element for specific time periods; and electric motor-driven contactors that control power to separate circuit sections.
- Features ammeters, loadmeters, and on/off switches to monitor and control the flow of electric current within circuits.
- Protective devices include current limiters and circuit breakers.
- To prevent element overheating, the deicing system is only used when the propellers are rotating, which applies to short tests and takeoff/inspection checks.
- System sequence: Specific steps describe the sequence for deicing on a Navajo PA31 aircraft (right-hand, right-hand outboard, left-hand inboard, and left-hand outboard propeller boots).
Propeller Synchronization and Synchrophasing
- Propeller synchronization systems are commonly used in multi-engine aircraft to synchronize engine rpm, reducing vibration, and undesirable beats.
- An electronic system matches the rpm of both engines, with blade phases being synchronized to reduce cabin noise.
Autofeathering System
- An auto-feather system is used typically for takeoff and landing procedures. The system automatically feathers the propeller if the engine power is lost. This leverages a solenoid valve that swiftly dumps the oil pressure— allowing the propeller cylinder to feather. The system uses two torque switches sensing low engine torque to trigger the feathering operation. This has a test-off-arm switch.
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