For Aircraft maintenance FAR 91.409 establishes minimum requirements pertaining to annual and 100-hour inspections. Not only does the FAA require these inspections, but they stipulate in FAR 91.405 that the owner/operator must maintain the airworthiness of the aircraft and engine during the time between the required inspections by having any airworthiness defects corrected and by ensuring that maintenance personnel make the proper entries in aircraft records approving the return to service. Although maintenance requirements will vary for different types of aircraft, the FAA states that experience shows most aircraft will need some type of preventive maintenance after every 25 hours of flying time and minor maintenance at least every 100 hours.