Heavy Maintenance — Heavy Maintenance Visit

Heavy Maintenance Visit

Heavy maintenance is the most resource-intensive phase of aircraft upkeep. An aircraft entering heavy maintenance may be completely stripped of its interior, have panels removed across the fuselage and wings, and be inspected rigorously over days, weeks or months.

Why Heavy Maintenance Is Necessary

Fatigue, corrosion and wear accumulate over thousands of flight cycles. Many structural elements and system components cannot be inspected or serviced without removing panels, seats or linings that line maintenance cannot access during a short ground stop. Regulatory requirements mandate these deeper inspections at defined intervals.

C Check vs D Check

C Check (every 20–24 months or approximately 6,000 flight hours): comprehensive inspection of aircraft systems, structures and components. Duration 1–2 weeks. The aircraft is typically inducted into a base maintenance facility.

D Check (every 6–12 years depending on aircraft type): the most extensive maintenance event. The aircraft is essentially stripped to its frame. Duration 4–6 weeks. Often coincides with major modifications, cabin refurbishments and avionics upgrades.

Economic Considerations

Heavy maintenance is expensive — a D Check on a widebody aircraft can cost $4–6 million or more. Airlines plan heavy maintenance events years in advance, scheduling them to minimise revenue impact. The balance between maintenance deferral (within regulatory limits) and early induction affects aircraft book value and resale prospects.

Global HMV Providers

Major independent MRO providers include Lufthansa Technik, ST Engineering, Air France Industries KLM Engineering & Maintenance and Turkish Technic. Many airlines also operate their own heavy maintenance facilities.