On rotorcraft like the MD500 the POH suggests that torque events be recorded in the aircraft maintenance logbook.
What are these events, are they common and how many are typically logged during the average flight?
Most western made helicopters have limitations on the amount of engine torque to which the transmission and drive dynamic components may be subjected. Exceeding the rated torque either transiently or for a specific length of time can trigger the need for special inspections or worse, an actual maintenance evolution. Depending on make and model, short transient excursions may be allowable under certain conditions. Many, if not all, Russian made equipment have well overbuilt transmissions / dynamic components and I have heard that some don't even have torque indicating instruments. Just keep pulling collective till max engine temp or engine droop. This comes at the expense of heavier transmissions though. Hope this helps.