Maintenance Repair & Overhaul or MRO refers to aeronautical maintenance activities delivered by approved actors specific to this sector. They form a set of strictly regulated, mandatory maintenance cycles, generally divided into 4 categories:
– Level A maintenance: to be performed monthly.
– Level B maintenance: to be performed every 3 months.
– Level C maintenance: to be performed every 12-18 months.
– Level D maintenance: to be done every 4-5 years.
The Maintenance Repair and Overhaulactivities include track maintenance, main structure maintenance, engine maintenance, and maintenance of components and equipment.