Maintenance Check Types

Maintenance checks in commercial aviation follow a structured schedule of increasing scope and complexity:

• Transit Check: Performed between flights (turnaround). Visual walk-around, fluid levels, tire condition, obvious damage. Duration: 30-60 minutes
• Daily Check: More thorough inspection at the end of each flying day. Includes cabin, systems, and maintenance log review. Duration: 2-4 hours
• A Check: Performed every 400-800 flight hours. Detailed inspection of specific systems and components on a rotating schedule. Aircraft out of service for 1-2 days. Typically done overnight at a line maintenance station
• C Check: Performed every 18-24 months or 4,000-6,000 flight hours. Comprehensive inspection requiring extensive access panels to be opened. Duration: 1-3 weeks in a maintenance hangar
• D Check (Heavy Maintenance Visit): The most extensive check, performed every 6-12 years. The aircraft is essentially stripped down to its bare structure for inspection, repair, and refurbishment. Duration: 4-8 weeks. Cost: $1-5 million+ depending on aircraft type

Modern maintenance programs are shifting toward MSG-3 (Maintenance Steering Group 3) methodology, which uses task-oriented scheduling rather than fixed letter-check intervals.