2A651 Volume 4 CDC UREs

The purpose of the 54H60-91 propeller pitchlock assembly is to prevent an engine overspeed due to a loss of hydraulic pressure. This means that if there is a loss of hydraulic pressure, the propeller pitchlock assembly will engage and prevent the propeller from spinning too fast, which could cause an engine overspeed.

The correct answer is "Speed set." In the 54H60-91 propeller, the speed set cam changes the tension of the speeder spring. This adjustment allows the governor pilot valve to maintain 100 percent rpm during alpha range operation.

When attempting to unfeather the 54H60-91 propeller in flight, the throttle must be positioned above FLT IDLE. This is because unfeathering the propeller requires an increase in engine power, which can only be achieved by moving the throttle lever above the FLT IDLE position.

The correct answer is "Barrel." The barrel is a part of the 54H60-91 propeller subassembly that is responsible for transmitting engine torque to the propeller blades. It acts as a housing for the propeller shaft and allows the torque to be transferred from the engine to the blades, enabling them to rotate and generate thrust.

The beta feedback shaft delivers the actual propeller blade angle from the blade to the control assembly. It is responsible for transmitting the position of the blade to the control system, allowing for precise control and adjustment of the propeller blade angle. The microadjusting ring, blade segment gear, and blade bushing are not directly involved in delivering the blade angle to the control assembly.

The differential gear train assembly on the 54H60-91 propeller is responsible for transmitting blade angle movement to the valve housing and driving the propeller governor flyweights. This allows for the adjustment of the propeller blade angle, which in turn controls the pitch and rotation of the propeller. By transmitting the blade angle movement to the valve housing, the differential gear train assembly ensures that the correct blade angle is maintained for efficient propeller operation. Additionally, by driving the propeller governor flyweights, it enables the propeller to automatically adjust its pitch based on engine and aircraft conditions.

The correct answer is "Wedge." On the 54H60-91 propeller, the stop levers on the low pitch stop are moved outward by a wedge.

The potentiometer in the T56 engine coordinator provides reference signals to the electronic TD amplifier that are proportional to the desired TIT (Turbine Inlet Temperature). A potentiometer is a variable resistor that can be adjusted to provide different levels of resistance. In this case, it is used to generate a signal that corresponds to the desired TIT, which is then sent to the TD amplifier for further processing.

The main pressure pump is responsible for supplying hydraulic pressure for normal propeller operation on the 54H60-91 propeller. The other options, auxiliary pressure, standby pressure, and backup pressure, are not capable of providing sufficient hydraulic pressure for normal propeller operation.

If the main filter becomes clogged on the 54H60-91 propeller, the bypass valve opens to assure continued flow. The bypass valve allows the fluid to bypass the clogged filter and continue flowing through the system. This ensures that the propeller continues to receive the necessary fluid for proper operation even if the main filter is not functioning correctly.

When the backup valve is opened on the 54H60-91 propeller, the hydraulic pressure routed to the governor pilot valve is used for the operation of reversing the propeller. This allows the propeller blades to change their pitch angle and create reverse thrust, which helps in slowing down or stopping the aircraft during landing or taxiing.

The auxiliary pump is used to feather or unfeather the propeller during static propeller operation on the 54H60-91 propeller.

When feathering the propeller on the 54H60-91 propeller, the mechanical linkage is opened by the manual feather cam. This cam is responsible for controlling the position of the feather actuating valve, allowing it to open and initiate the feathering process. The throttle, beta shaft, and pilot valve do not directly act on the mechanical linkage to open the feather actuating valve in this propeller system.

The hub mounting bulkhead provides a means for balancing the propeller on the 54H60-91 propeller. Balancing the propeller is important to ensure smooth operation and reduce vibrations. The hub mounting bulkhead is a structural component that connects the propeller hub to the engine shaft, and it is designed to provide stability and balance to the propeller assembly.

The correct answer is 109 to 113%. The 54H60-91 propeller governor speeder spring tension positions the pilot valve to maintain the propeller rpm in the beta range within this specific range. This means that the speeder spring tension is set in such a way that it allows the propeller to maintain a rotational speed of 109 to 113% of the maximum rated rpm while operating in the beta range.

During feather operation on the 54H60-91 propeller, the pressure cutout switch contacts are opened between approximately 600 to 800 psi.

The pitchlock control cam is the component that mechanically holds the stationary and rotating pitchlock ratchets apart during reversing and unfeathering operations. It ensures that the propeller blades are locked in the desired position and prevents any unwanted movement or rotation. The other options, such as the pitchlock ratchet piston, externally threaded ring, and externally splined spacer ring, do not perform this specific function.

During normal propeller operation on the 54H60-91 propeller, the output of the main pressure and main scavenge pumps is used.

The correct answer is "Pilot." The question is asking about which valve, contained in the valve housing, controls the flow of hydraulic fluid to and from the dome assembly on the 54H60-91 propeller. The correct valve for this function is the pilot valve.

The correct answer is "Check." In the context of the question, a "Check" valve is a type of valve that opens to allow the output of the standby pump to combine with the output of the main pump. This valve allows the flow of fluid in one direction only, preventing any backflow.

The rotating cam needs to turn while the stationary cam remains fixed. Ball bearings are designed to allow smooth rotation between two parts, while maintaining a fixed position for the other part. Roller shafts, track slopes, and roller bearings do not provide the same level of smooth rotation and fixed positioning as ball bearings. Therefore, ball bearings are the correct choice for this situation.

The low pitch stop assembly on the 54H60-91 propeller prevents the propeller from going into the beta range when the throttle is positioned in the alpha range. This means that it restricts the propeller blades from moving into a position where they can generate reverse thrust. By doing so, it ensures that the propeller operates within the desired range and prevents any unintended changes in thrust direction.

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When the throttle is moved to the GROUND IDLE position on the 54H60-91 propeller, the coordinator pointer indicates a degree setting of 18 degrees on the protractor.

When the pressure builds to between 240 and 280 psi on the 54H60-91 propeller, the servo valve is unseated. This allows the stop levers to retract. The servo valve is responsible for controlling the flow of hydraulic fluid to the propeller blades, and when it is unseated, it allows the hydraulic pressure to decrease, causing the stop levers to retract. This action allows the propeller to change pitch and adjust its RPM.

The throttle in the controllable pitch range is responsible for coordinating the blade pitch and engine fuel flow. The throttle controls the amount of fuel being supplied to the engine, which in turn affects the power output. Simultaneously, it adjusts the blade pitch to optimize the efficiency and performance of the propeller. By coordinating these two factors, the throttle ensures smooth and controlled operation of the aircraft in the controllable pitch range.

During feathering operation on the 54H60-91 propeller, the feather valve is positioned to the forward end of the dome piston. This means that hydraulic fluid is being metered to the forward end of the dome piston.

The transfer bearing is the component that directs hydraulic fluid from the pump housing to the barrel assembly on the 54H60-91 propeller. The valve housing, low pitch stop, and pitchlock regulator are not involved in this process.

The correct answer is "dome piston from decreasing blade angle below 23.3 degrees +/- .5 degrees." The low pitch stop on the 54H60-91 propeller is responsible for preventing the dome piston from decreasing the blade angle below 23.3 degrees +/- .5 degrees. This is important to maintain the optimal pitch angle for efficient propeller operation. The other options are incorrect because they either refer to the propeller barrel instead of the dome piston or mention a different blade angle limit.

The pitchlock control cam prevents engagement of the stationary and rotating ratchets at blade angles below 25° and above 55°.

The correct answer is the Beta segment gear. The Beta segment gear is used in place of a shim plate on the No. 1 blade of the 54H60-91 propeller. This component helps to adjust the pitch of the blade and maintain proper functioning of the propeller system.

The standby pressure pump assists the main pressure pump when large blade angle movements are required on the 54H60-91 propeller.

The condition lever GND STOP position is only effective on the ground because the circuits made in this position are completed through the landing gear touchdown switch. This switch is activated when the aircraft's landing gear makes contact with the ground, allowing the condition lever to be moved to the GND STOP position. This position helps prevent accidental movement of the condition lever during ground operations, ensuring the safety of the aircraft on the ground.

When the throttle is positioned in the beta range on the 54H60-91 propeller, the cam that disarms the NTS (Negative Torque Sensing) system linkage is the manual feather cam. This cam allows the propeller blades to be manually feathered, which means they are rotated to a flat pitch position to minimize drag and allow for a controlled descent or landing in case of an engine failure or emergency situation. The other options, such as beta follow-up, speed set, and beta set, do not specifically relate to disarming the NTS system linkage in the beta range.

The correct answer is Synchrophaser disarming. The synchrophaser is a device that synchronizes the propellers on a multi-engine aircraft to reduce vibration and noise. When the throttle is moved into the flight idle gate, the synchrophaser needs to be disarmed to prevent any interference with the propeller governor speed bias servo assembly. Therefore, the switch located in the control quadrant activates the synchrophaser disarming function.

During beta range operation on the 54H60-91 propeller, the movement of the pilot valve is facilitated by cams and mechanical linkage. This means that the cams and mechanical linkage mechanism are responsible for controlling the position and movement of the pilot valve, allowing for precise control and adjustment of the propeller's beta range operation.

The function of the pitchlock regulator on the 54H60-91 propeller is to prevent the blades from decreasing pitch if hydraulic pressure is lost. This means that even if there is a loss of hydraulic pressure, the pitch of the blades will remain in their current position and not change. This is an important safety feature to ensure that the propeller continues to provide thrust in the event of a hydraulic failure.

The pressure cutout switch is the primary electrical ground for energizing the feather override holding coil on the 54H60-91 propeller. This switch is responsible for monitoring the oil pressure in the propeller system. When the oil pressure drops below a certain threshold, the pressure cutout switch opens, which allows the feather override holding coil to be energized. This coil prevents the propeller from automatically feathering in the event of an engine failure, allowing the pilot to maintain control of the aircraft.

The correct answer is "Manual feather and beta set." The alpha shaft controls the 54H60-91 propeller unfeathering operation, and two cams on the alpha shaft are responsible for this control. The "Manual feather" cam controls the manual feathering of the propeller, allowing the pilot to manually feather the propeller blades. The "beta set" cam controls the beta setting of the propeller, which is the angle at which the propeller blades are set to optimize performance during certain flight conditions. Therefore, both the manual feather and beta set cams play a role in controlling the unfeathering operation of the propeller.

During an underspeed condition on the 54H60-91 propeller, the speeder spring moves the pilot valve. The speeder spring is responsible for regulating the hydraulic pressure and adjusting the propeller blade angle to maintain the desired speed. When the propeller speed drops below the set value, the speeder spring contracts, causing the pilot valve to move and increase the hydraulic pressure, which in turn adjusts the blade angle to increase the propeller speed back to the desired level.

When the 54H60-91 propeller feathers, it means that the blades of the propeller are rotated to a position where they are parallel to the airflow, reducing drag and allowing the aircraft to glide. This process is initiated by the feather pump. The main scavenge pump is responsible for scavenging oil from the propeller hub and returning it to the oil tank. When the propeller feathers, the main scavenge pump's output decreases because there is less oil to scavenge from the propeller hub. Therefore, the correct answer is Main scavenge.

The low-pressure relief valve is responsible for setting and maintaining a pressure differential of about 100 psi between the system pressure and the increase- or decrease-pitch pressure on the 54H60-91 propeller. This valve helps to regulate the pressure and ensure that it does not exceed a certain level, preventing any damage or malfunction in the system.

During beta range operation on the 54H60-91 propeller, the rotation of the beta follow-up cam moves the mechanical linkage to center the governor pilot valve.

The correct answer is "Pilot." In the event that the feather valve fails during feathering operation on the 54H60-91 propeller, the pilot valve serves as a backup. The pilot valve is responsible for controlling the flow of hydraulic fluid to the feather actuating cylinder, which is necessary for feathering the propeller. If the feather valve fails, the pilot valve ensures that the propeller can still be feathered using the backup system.