Aviation Terms->D Check
This is most comprehensive aircraft maintenance check for the airplane, also known as a Heavy Maintenance Visit (HMV). This check occurs approximately every 4–5 years. This is the check that, more or less, takes the entire airplane apart for inspection. This requires even more space and time than all other checks, and must be performed at a maintenance base. Often, older aircraft being phased out of a particular airlines' fleet are stored or scrapped upon reaching their next check due to the high costs involved in comparison to the aircraft's value.