The Conquest utilises a propeller syncrophasing system to reduce noise levels in the cabin and reduce vibration levels throughout the airframe. The system is a combination syncronising/syncrophasing system which uses the right hand engine as the master engine and the left hand engine as the slave engine.
Difference between syncronising and synchrophasing.
Syncronising is the matching of the two propeller RPM’s to remove the inherent ‘beat’ that is encountered during twin engine operations.
Syncrophasing is the reduction of airframe vibrations by changing the position of the propeller blades in relation to each other after syncronisation has occurred. To explain this better please refer to the next picture for a pictorial view of syncrophasing as seen from the front of an aeroplane.
Both propellers vertical after Syncronising
Left (slave) propeller 'phased' slightly to reduce airframe vibration.
The syncrophasing system on the Conquest utilises a solid state controller in conjunction with the two electronic fuel computers. RPM inputs for the syncrophasing system are supplied from the monopole speed sensors installed in each fuel control unit and are transmitted to the syncrophasing system via the fuel computers.
The syncrophaser then determines the RPM difference and transmits an output signal to the left electronic propeller governor to adjust the RPM as necessary to match the propeller RPM with the right hand propeller.
Synchrophasing is achieved by the pilot adjusting a rotary knob located on the centre pedestal to reduce the noise/vibration levels that are being experienced inside the cabin.
The syncrophasing system is controlled by a two position switch on the centre pedestal. The switch is labeled PROP SYNC and has an ON or OFF position. The syncrophasing system is wired through the 'up-circuit' of the landing gear selector switch and is therefore only operational when the landing gear is in the retracted position.
Synchrophasing is not available in manual mode as the system cannot operate on the mechanical governor alone.
Conquests with serial numbers 441-0001 to 441-0339 have a 20 second delay from selection of on through to capture. Subsequent aircraft, or, aircraft incorporating service Kit SK441-79 have no time delay from selection through to capture.
This system is known as the Power Management System and is not incorporated on all of FLIGHT.ORG Air’s fleet. Once the synchrophasing system has captured the propeller RPM’s the light on the centre pedestal will illuminate. This light will remain illuminated whilst the syncrophasing system is operating, i.e. it should be continuously illuminated in flight.