Engine RPM information is supplied by easily installed Hall Effect Sensors.
The TwinSync has a unique safety feature that brings the running engine immediately to idle in the event that one engine stops with no change in throttle stick.
This feature prevents loss of control when one engine stops while flying the model. The pilot can regain control of the idling engine by simply moving the throttle stick to idle. Control is then returned to the throttle stick and the pilot has full control.
The TwinSync has another safety feature to kill both engines if the loss of transmitter signal is detected on a FM radio system. This feature operates similar to how PCM transmitters and receivers operate. If a PCM radio is used with the TwinSync it will operate as normal and the TwinSync has no impact on PCM failsafe operation.
The TwinSync has several additional modes of operation adding capabilities beyond just keeping the engines synchronized. These modes are detailed in the TwinSync manual.
See the manual of the TwinSync for more information: TwinSync-Manual