Our elderly R44 has flown 300hrs this year. 25hr oil changes done by me (pilot not engineer), 50, 100 and annual done as scheduled albeit with 10% extensions signed off by engineer. In this time we had one failure that required an unscheduled trip to maintenance (aircaft off line for 3 weeks) and a couple of snags that were dealt with at the next sheduled maintenance.
Hope that helps.