Following the accident in Australia, Cessna promptly issued service letter SEL57-06 which recommended owners of Cessna 210G thru T210R aircraft to determine the operational use of their aircraft, perform the prescribed inspections outlined in the service letter, and report findings to Cessna. SEL57-06 listed two distinct categories for determining operational use—typical usage environment and severe usage environment. An airplane is considered to be operating in severe conditions if the airplane has been engaged in operations at low altitudes such as pipeline patrol, fish or game spotting, aerial applications, police patrol, sightseeing, livestock management, etc. more than 30% of its life or the duration of each flight is less than 30 minutes. The aircraft is said to be operating in the typical usage environment if neither of the aforementioned conditions are met. However, if the aircraft’s records nor the pilot’s personal experience are satisfactory to determine its usage, then the severe inspection criteria apply. The inspection criteria are different depending on which of the two categories the aircraft falls in.