Speed and phase evidence

A fictional two-propeller training display reports both rotational speeds as 1800 revolutions per minute. A separate phase indication is not available, and the exercise provides no vibration measurement or blade-tracking result. One learner concludes that the propellers must be in the required phase relationship and perfectly balanced. Another states only what the two speed indications support. The task asks for the distinction between synchronization and synchrophasing and the remaining evidence gaps. The display is a paper example, not an actual aircraft test. It supplies no authority to adjust a governor, engage a system during a particular flight phase, add weights or operate with a defect. A complete answer must avoid inferring an unmeasured structural or phase condition from equal numerical speed alone.